Intel Network Card 82555 User Manual
82555 10/100 Mbps LAN Physical Layer  
Interface  
Networking Silicon  
Datasheet  
Product Features  
■ Optimal integration for lower cost solutions ■ Performance enhancements  
—Integrated 10/100 Mbps single chip  
physical layer interface solution  
—Flow control support for IEEE 802.3x  
Auto-Negotiation and Bay Technologies  
PHY Base* scheme  
—Complete 10/100 Mbps MII compliance  
with MDI support  
—Adaptive Channel Equalizer for greater  
functionality over varying cable lengths  
—Full duplex operation in 10 Mbps and  
100 Mbps modes  
—High tolerance to extreme noise  
conditions  
—IEEE 802.3u Auto-Negotiation support  
for 10BASE-T half and full duplex,  
100BASE-TX half and full duplex, and  
100BASE-T4 configurations  
—Very low emissions  
—Jabber control circuitry to prevent data  
loss in 10 Mbps operation  
—Parallel detection algorithm for legacy  
support of non-Auto-Negotiation  
enabled link partner  
—Auto-polarity correction for 10BASE-T  
—Software compatible with 82557 drivers  
■ Repeater functionality  
—Integrated 10BASE-T transceiver with  
built in transmit and receive filters  
—Repeater mode operation  
—Support for forced speed of 10 Mbps  
and 100 Mbps  
—Glueless interface to T4-PHY for  
combination TX/T4 designs with single  
magnetics  
—Automatic carrier disconnect for IEEE  
802.3u compliance  
—Glueless support for 4 LEDs: activity,  
link, speed, and duplex  
—Auto-Negotiation enable/disable  
capability  
—LED function mapping support via MDI  
—Low external component count  
—Receive port enable function  
—Support for 32 configurable addresses  
—Single 25 MHz clock support for 10  
Mbps and 100 Mbps (crystal or  
oscillator)  
—Narrow analog side (14 mm) for tight  
packing in repeater and switch designs  
—Single magnetics for 10 Mbps and 100  
Mbps operation  
—QFP 100-pin package  
Notice:  
Notice:  
Document Number: 666252-004  
Revision 2.0  
March 1998  
 
Networking Silicon — 82555  
Contents  
1.0  
2.0  
INTRODUCTION..........................................................................................................................1  
1.1  
1.2  
Functional Overview........................................................................................................1  
Compliance to Industry Standards ..................................................................................1  
ARCHITECTURAL OVERVIEW...................................................................................................3  
2.1  
2.2  
2.3  
100 Mbps Mode...............................................................................................................3  
10 Mbps Mode.................................................................................................................4  
Media Independent Interface (MII) ..................................................................................5  
3.0  
PIN DEFINITIONS........................................................................................................................7  
3.1  
3.2  
3.3  
3.4  
3.5  
3.6  
3.7  
3.8  
3.9  
Pin Types .......................................................................................................................8  
Clock Pins ......................................................................................................................8  
Twisted Pair Ethernet (TPE) Pins ...................................................................................8  
Media Independent Interface (MII) Pins .........................................................................8  
Media Access Control/Repeater Interface Control Pins .................................................9  
LED Pins ......................................................................................................................10  
External Bias Pins ........................................................................................................10  
Miscellaneous Control Pins ..........................................................................................11  
Power and Ground Pins ...............................................................................................12  
4.0  
100BASE-TX ADAPTER MODE OPERATION..........................................................................13  
4.1  
4.2  
100BASE-TX Transmit Clock Generation .....................................................................13  
100BASE-TX Transmit Blocks ......................................................................................13  
4.2.1  
4.2.2  
4.2.3  
4.2.4  
100BASE-TX 4B/5B Encoder ....................................................................13  
100BASE-TX Scrambler and MLT-3 Encoder ...........................................14  
100BASE-TX Transmit Framing ................................................................15  
Transmit Driver ..........................................................................................16  
4.3  
100BASE-TX Receive Blocks .......................................................................................16  
4.3.1  
4.3.2  
4.3.3  
4.3.4  
4.3.5  
Adaptive Equalizer.....................................................................................17  
Receive Clock and Data Recovery ............................................................17  
MLT-3 Decoder, Descrambler, and Receive Digital Section......................17  
100BASE-TX Receive Framing .................................................................17  
100BASE-TX Receive Error Detection and Reporting...............................17  
4.4  
4.5  
100BASE-TX Collision Detection ..................................................................................17  
100BASE-TX Link Integrity and Auto-Negotiation Solution...........................................18  
4.5.1  
4.5.2  
4.5.3  
Link Integrity...............................................................................................18  
Auto-Negotiation ........................................................................................18  
Combination Tx/T4 Auto-Negotiation Solution...........................................18  
4.6  
4.7  
Auto 10/100 Mbps Speed Selection..............................................................................19  
Adapter Mode Addresses..............................................................................................19  
5.0  
10BASE-T FUNCTIONALITY IN ADAPTER MODE ..................................................................21  
5.1  
5.2  
10BASE-T Transmit Clock Generation..........................................................................21  
10BASE-T Transmit Blocks...........................................................................................21  
5.2.1  
5.2.2  
10BASE-T Manchester Encoder................................................................21  
10BASE-T Driver and Filter .......................................................................21  
5.3  
10BASE-T Receive Blocks............................................................................................21  
5.3.1  
5.3.2  
10BASE-T Manchester Decoder................................................................21  
10BASE-T Twisted Pair Ethernet (TPE) Receive Buffer and Filter............21  
Datasheet  
iii  
 
82555 — Networking Silicon  
Contents  
5.3.3  
10BASE-T Error Detection and Reporting .................................................22  
5.4  
5.5  
5.6  
5.7  
10BASE-T Collision Detection.......................................................................................22  
10BASE-T Link Integrity................................................................................................22  
10BASE-T Jabber Control Function..............................................................................22  
10BASE-T Full Duplex ..................................................................................................23  
6.0  
7.0  
REPEATER MODE....................................................................................................................25  
6.1  
6.2  
Special Repeater Features............................................................................................25  
Connectivity...................................................................................................................25  
MANAGEMENT DATA INTERFACE..........................................................................................27  
7.1  
7.2  
MDI Frame Structure.....................................................................................................27  
MDI Registers................................................................................................................28  
7.2.1  
7.2.2  
7.2.3  
MDI Registers 0 - 7....................................................................................28  
MDI Registers 8 - 15..................................................................................31  
MDI Registers 16 - 31................................................................................31  
8.0  
AUTO-NEGOTIATION FUNCTIONALITY..................................................................................35  
8.1  
8.2  
Description ....................................................................................................................35  
Parallel Detect and Auto-Negotiation ............................................................................36  
9.0  
LED DESCRIPTIONS ................................................................................................................39  
RESET AND MISCELLANEOUS TEST MODES.......................................................................41  
10.0  
10.1  
10.2  
10.3  
10.4  
Reset.............................................................................................................................41  
Loopback.......................................................................................................................41  
Scrambler Bypass .........................................................................................................41  
Test Port........................................................................................................................41  
11.0  
ELECTRICAL SPECIFICATIONS AND TIMING PARAMETERS ..............................................43  
11.1  
11.2  
11.3  
Absolute Maximum Ratings ..........................................................................................43  
General Operating Conditions ......................................................................................43  
DC Characteristics ........................................................................................................43  
11.3.1  
11.3.2  
11.3.3  
MII DC Characteristics ..............................................................................43  
10BASE-T Voltage/Current DC Characteristics ........................................43  
100BASE-TX Voltage/Current DC Characteristics ...................................44  
11.4  
AC Characteristics.........................................................................................................45  
11.4.1  
11.4.2  
11.4.3  
11.4.4  
11.4.5  
11.4.6  
11.4.7  
11.4.8  
11.4.9  
MII Clock Specifications.............................................................................45  
MII Timing Parameters ..............................................................................46  
Repeater Mode Timing Parameters ..........................................................47  
Transmit Packet Timing Parameters .........................................................48  
Squelch Test Timing Parameters ..............................................................48  
Jabber Timing Parameters ........................................................................49  
Receive Packet Timing Parameters ..........................................................49  
10BASE-T Normal Link Pulse (NLP) Timing Parameters .........................50  
Auto-Negotiation Fast Link Pulse (FLP) Timing Parameters ....................50  
11.4.10 Reset Timing Parameters .........................................................................51  
11.4.11 X1 Clock Specifications ............................................................................51  
11.4.12 100BASE-TX Transmitter AC Specification ..............................................52  
12.0  
iv  
82555 PACKAGE INFORMATION.............................................................................................53  
Datasheet  
 
Networking Silicon — 82555  
1.0  
Introduction  
The 82555 is a highly integrated, physical layer interface solution designed for 10 and 100 Mbps  
Ethernet systems based on the IEEE 10BASE-T and 100BASE-TX specifications. 100BASE-TX is  
an IEEE 802.3 physical layer specification for use over two pairs of Category 5 unshielded twisted  
pair or Type 1 shielded twisted pair cable. 100BASE-TX defines a signaling scheme not only for  
100 Mbps, but also provides CSMA/CD compatibility with the 10 Mbps IEEE 802.3 10BASE-T  
signaling standard.  
1.1  
Functional Overview  
The 82555 is designed to work in two modes: Data Terminal Equipment (DTE) for adapters and  
repeater for hubs and switches. When configured to DTE (adapter) mode, the 82555 incorporates  
all active circuitry required to interface 10/100 Mbps Ethernet controllers and CSMA/CD MAC  
components to 10 Mbps and 100 Mbps networks. In this and other documents the 82555 may be  
referred to as the DTE, Physical Medium Device (PMD), or Physical Layer Medium (PLM). It  
supports a direct glueless interface to Intel components such as the 82557 Fast Ethernet controller.  
The 82555 also supports the Media Independent Interface (MII) signals as specified in the IEEE  
802.3u standard. The figure below shows how the 82555 fits into a 10/100 Mbps Ethernet adapter  
design.  
Pair 1  
Intel 82555  
Controller/MAC  
Pair 2  
Magnetics  
System Bus Interface  
Figure 1. 82555 10/100 Mbps Ethernet Solution  
When configured to repeater mode, the 82555 incorporates several features that allow it to function  
as a Class I or MII level repeater. Section 6.0, “Repeater Mode” on page 25 describes the 82555 in  
a repeater type of application.  
1.2  
Compliance to Industry Standards  
When operating in 100 Mbps mode, the 82555 complies with IEEE 802.3u 100BASE-TX  
specification. The PMD section with the related changes established in 802.3u 100BASE-TX  
complies with ANSI X3.263:1995 TP-PMD, Revision 2.2.  
When operating in the 10 Mbps mode, the 82555 complies with the IEEE 802.3 10BASE-T  
specification.  
Datasheet  
1
 
82555 — Networking Silicon  
The 82555 also complies with the IEEE 802.3u Auto-Negotiation and the IEEE 802.3x Full Duplex  
Flow Control sections. The MAC interface on the 82555 is a superset of the IEEE 802.3u Media  
Independent Interface (MII) standard.  
2
Datasheet  
 
Networking Silicon — 82555  
2.0  
Architectural Overview  
The 82555 is an advanced combination of both digital and analog logic which combine to provide a  
functional stack between the Media Independent Interface (MII) and the wire through the  
magnetics. Figure 2 shows a general block diagram of the 82555 component.  
Figure 2. 82555 Simplified Block Diagram  
2.1  
100 Mbps Mode  
In 100BASE-TX mode the 82555 digital subsection performs all signal processing of digital data  
obtained from the analog reception and the data to be driven into the analog transmit subsection.  
This includes 4B/5B encoding/decoding, scrambling/descrambling, carrier sense, collision  
detection, link detection, Auto-Negotiation, data validation, and providing MII to the Media  
Access Controller (MAC). The 82555 supports the IEEE defined MII as its MAC interface and  
expects the controller to drive the Management Data Input/Output and Management Data Clock  
signals to perform the management functions.  
In 100BASE-TX mode, the analog subsection of the 82555 performs two functions:  
• Transmit: The 82555 converts a digital 125 Mbps stream into MLT-3 format and drives it  
through the transmit differential pair onto the physical medium.  
Datasheet  
3
 
 
82555 — Networking Silicon  
• Receive: The 82555 takes receive analog MLT-3 data from the receive differential pair and  
converts it into a digital 125 Mbps stream, recovering both clock and data signals.  
MII TX Interface  
MII RX Interface  
4b/5b  
Encoding  
4b/5b  
Decoding  
Scrambler  
De-scrambler  
Serialization  
Serial to 5B  
NRZI to NRZ  
MLT3 to NRZI  
NRZ to NRZI  
NRZI to MLT3  
Magnetics Module  
1
2
3
4
5
6
7
8
RJ-45 Connector  
Figure 3. 82555 Analog Logic  
2.2  
10 Mbps Mode  
The 82555 operation in 10BASE-T mode is similar to the 82555 operation in 100BASE-TX mode.  
Manchester encoding and decoding is used instead of 4B/5B encoding/decoding and scrambling/  
descrambling. In addition, the Transmit Clock and Receive Clock (MII clock signals) provide 2.5  
MHz instead of 25 MHz.  
4
Datasheet  
 
Networking Silicon — 82555  
The 82555 provides a glueless interface to Intel components such as the 82557 Fast Ethernet  
Controller, as well as any MII compatible device. Figure 4 shows a schematic-level diagram of the  
82557 Fast Ethernet controller implementation connected to the 82555 using the MII interface.  
Flash  
(optional)  
EEPROM  
(optional)  
RXD[3:0]  
RXC  
RXERR  
RXDV  
CRS  
COL  
TXD[3:0]  
TXC  
TXEN  
82557  
82555  
MDC  
MDIO  
RESET  
PCI Bus Signals  
Figure 4. Intel 82557/82555 Solution  
2.3  
Media Independent Interface (MII)  
The 82555 supports the Media Independent Interface (MII) as its primary interface to the MAC.  
The MII Interface is summarized in Table 1.  
Table 1. 82555 MII  
Signal  
Name  
Clock  
Reference  
MII Signal Supported  
by the 82555?  
Description  
Direction  
From 82555  
TXC  
Transmit Clock  
--  
Yes  
(adapter mode only)  
From MAC  
TXD[3:0] Transmit Data  
TXC  
TXC  
Yes  
Yes  
TXEN  
COL  
CRS  
RXC  
Transmit Enable  
Collision Detect  
Carrier Sense  
Receive Clock  
From MAC  
From 82555  
From 82555  
From 82555  
From 82555  
From 82555  
From 82555  
Asynchronous Yes  
Asynchronous Yes  
--  
Yes  
Yes  
Yes  
Yes  
RXD[3:0] Receive Data  
RXC  
RXC  
RXC  
RXDV  
Receive Data Valid  
RXERR  
Receive Error  
Management Data  
Clock  
MDC  
From manager  
From manager  
--  
Yes  
Yes  
Management Data  
Input/Output  
MDIO  
MDC  
Datasheet  
5
 
   
82555 — Networking Silicon  
Table 1. 82555 MII  
Signal  
Name  
Clock  
Reference  
MII Signal Supported  
by the 82555?  
Description  
Direction  
Transmit Error  
(repeater mode only)  
TXERR  
From RIC  
TXC  
Yes  
6
Datasheet  
 
Networking Silicon — 82555  
3.0  
Pin Definitions  
All active digital pins are defined to have transistor-to-transistor logic voltage levels except the X1  
and X2 crystal signals. The transmit differential and receive differential pins are specified as analog  
outputs and inputs, respectively.  
The figure below show the pin locations on the 82555 component. The following subsections  
describe the pin functions.  
Figure 5. 82555 Pin Numbers and Labels  
Datasheet  
7
 
82555 — Networking Silicon  
Pin allocation is based on a 100-lead quad flat package. All pin locations are based on printed  
circuit board layout and other design constraints.  
3.1  
Pin Types  
Pin Type  
Description  
This type of pin is an input pin to the 82555.  
I
O
I/O  
B
This type of pin is an output pin from the 82555.  
This type of pin is both an input and output pin for the 82555.  
This pin is used as a bias pin. The bias pin is either pulled up or down with a resistor. The bias pin  
may also be used as an external voltage reference.  
3.2  
Clock Pins  
Symbol  
X1  
Pin  
56  
Type  
Name and Function  
I
Crystal Input One. X1 and X2 can be driven by an external 25 MHz crystal.  
Otherwise, X1 may be driven by an external MOS level 25 MHz oscillator  
when X2 is left floating. (The crystal should have a tolerance of 50 PPM or  
better.)  
X2  
55  
O
Crystal Output Two. X1 and X2 can be driven by an external 25 MHz  
crystal. Otherwise, X1 may be driven by an external MOS level 25 MHz  
oscillator when this pin is left floating.  
3.3  
Twisted Pair Ethernet (TPE) Pins  
Symbol  
TDP  
Pin  
47  
Type  
Name and Function  
O
Transmit Differential Pair. These pins send the serial bitstream for  
transmission on an unshielded twisted pair (UTP) cable. The current-driven  
differential driver can be two-level (10BASE-T or Manchester) or three-level  
(100BASE-TX or MLT-3) signals depending on the operating mode. These  
signals interface directly with an isolation transformer.  
TDN  
48  
RDP  
RDN  
33  
34  
I
Receive Differential Pair. These pins receive the serial bitstream from the  
isolation transformer. The bitstream can be two-level (10BASE-T or  
manchester) or three-level (100BASE-TX or MLT-3) signals depending on the  
operating mode.  
3.4  
Media Independent Interface (MII) Pins  
Symbol  
Pin  
97  
Type  
Name and Function  
RXD3  
RXD2  
RXD1  
RXD0  
O
Receive Data. In 100 Mbps and 10 Mbps mode, data is transferred across  
these four lines one nibble at a time.  
96  
95  
92  
8
Datasheet  
 
Networking Silicon — 82555  
Symbol  
Pin  
90  
Type  
Name and Function  
RXC  
O
Receive Clock. The Receive Clock may be either 25 MHz or 2.5 MHz  
depending on the 82555’s operating speed (25 MHz for 100 Mbps and 2.5  
MHz for 10 Mbps). The Receive Clock is recovered directly from incoming  
data and is continuous into the Media Access Controller (MAC). Thus, it must  
be resynchronized in 10 Mbps mode at the start of each incoming packet.  
RXDV  
86  
87  
O
O
I
Receive Data Valid. This signal indicates that the incoming data on the  
RSC[3:0] pins are valid.  
RXERR  
Receive Error. The RXERR signal indicates to the 82555 that an error has  
occurred during frame reception.  
TXD3  
TXD2  
TXD1  
TXD0  
71  
70  
69  
68  
Transmit Data. In 100 Mbps and 10 Mbps mode, data is transferred across  
these four lines one nibble at a time.  
TXC  
60  
I/O  
Transmit Clock. The Transmit Clock may be either 25 MHz or 2.5 MHz  
depending on the 82555’s operating speed (25 MHz for 100 Mbps and 2.5  
MHz for 10 Mbps). The Transmit Clock outputs a continuous clock into the  
MAC that is generated directly from the external clock source in DTE  
(adapter) mode. In repeater mode, the TXC is an input signal operating at  
either 25 MHz or 2.5 MHz depending on the operating speed, which is  
typically clocked by a receiver interface device.  
TXEN  
TXERR  
CRS  
79  
59  
82  
85  
I
Transmit Enable. The Transmit Enable signal indicates to the 82555 that  
valid data is present on the TXD[3:0] pins.  
I
Transmit Error. The TXERR signal indicates to the 82555 that an error has  
occurred during transmissions of a frame.  
O
O
Carrier Sense. The Carrier Sense signal indicates to the 82555 that traffic is  
present on the link. CRS is an asynchronous output signal.  
COL  
Collision Detect. The Collision Detect signal operates in half duplex mode  
and indicates to the 82555 that a collision has occurred on the link. COL is an  
asynchronous output signal to the controller.  
MDIO  
MDC  
80  
81  
I/O  
II  
Management Data Input/Output. The MDIO signal is a bidirectional data pin  
for the Management Data Interface (MDI).  
Management Data Clock. The MDC signal functions as a clock reference for  
the MDIO signal. MDC should operate at a maximum frequency of 2.5 MHz  
3.5  
Media Access Control/Repeater Interface Control Pins  
Symbol  
Pin  
Type  
Name and Function  
RXCONG 77  
I
Receive Congestion. If the following conditions exist, the RXCONG is an  
active high and indicates an overrun on the controller receive side:  
•
Full duplex PHY Base (Bay Technologies) flow control DTE (adapter)  
mode  
•
•
Full duplex signal (FDX_N) is high  
Full duplex technology is active through Auto-Negotiation  
PORTEN  
76  
I
Port Enable. In repeater mode when the PORTEN signal is low, the following  
signals will be tri-stated: RXD[3:0], RXC, RXDV, and RXERR.  
Datasheet  
9
 
82555 — Networking Silicon  
Symbol  
Pin  
Type  
Name and Function  
TXRDY  
(TOUT)  
4
5
O
This pin is multiplexed and can be used for one of the following:  
Transmit Ready. If full duplex and PHY Base (Bay Technologies) flow control  
modes are enabled, the TXRDY signal enables transmission while it is  
asserted.  
TOUT. When the Test Enable signal is activated, this signal functions as the  
Test Output port.  
FDX_N  
I/O  
Full Duplex. In DTE (adapter) mode, this active low output signal reports the  
result of the duplex configuration to the MAC. This pin can also operate as  
the LED driver and will be an active low for all technologies.  
In repeater mode, this signal is used for Auto-Negotiation advertisement to  
the 82555’s link partner and activates the PHY Base (Bay Technologies) flow  
control if 100BASE-TX full duplex is the highest common technology between  
the 82555 and its link partner.  
3.6  
LED Pins  
Symbol  
Pin  
Type  
Name and Function  
ACTLED  
12  
11  
O
Activity LED. This signal indicates either transmit or receive activity. When  
activity is present, the ACTLED is on. When no activity is present, the  
ACTLED is off.  
LILED  
O
Link Integrity LED. This signal indicates the link integrity. If a valid link is  
present in either 10 Mbps or 100 Mbps, the LILED is on; and if an invalid link  
is preset, LILED is off.  
For a combination design board, the LILED should be connected to the TX  
technology LED.  
SPEED-  
LED  
13  
O
Speed LED  
This signal is used to indicate the speed of operation. For 100 Mbps, the  
SPEEDLED will be on; and for 10 Mbps, the SPEEDLED will be off.  
3.7  
External Bias Pins  
Symbol  
Pin  
Type  
Name and Function  
RBIAS100 44  
B
Bias Reference Resistor 100. A 634 Ω resistor should be connected from  
this pin to ground.  
RBIAS10  
PD1  
43  
B
I
Bias Reference Resistor 10. A 768 Ω resistor should be connected from  
this pin to ground.  
42  
Pull Down One. A 10 KΩ resistor should be connected from this pin to  
ground.  
PD2  
100  
I
Pull Down One. A 1 KΩ resistor should be connected from this pin to  
ground.  
Note: The resistor values described for the external bias pins are only recommended values and may  
require to be fine tuned for various designs.  
10  
Datasheet  
 
Networking Silicon — 82555  
3.8  
Miscellaneous Control Pins  
Symbol  
Pin  
Type  
Name and Function  
RESET  
1
I
I
Reset. The Reset signal is active high and resets the 82555. A reset pulse  
width of at least 1 µs should be used.  
FRC100  
51  
This pin is multiplexed and can be used for one of the following:  
(MACTYP)  
Force 100/10 Mbps. In repeater mode, this pin configures the repeater to  
either 100 Mbps (active high) or to 10 Mbps (active low).  
MAC Type. In DTE (adapter) full duplex mode, if this input signal is high, the  
82555 drives 82557 mode. If this input signal is low, the 82555 drives a  
generic MII MAC mode.  
PHYA4  
(TIN)  
22  
52  
I
This pin is multiplexed and can be used for one of the following:  
PHY Address 4. In repeater mode, this signal represents the fifth bit for  
address port configuration.  
TIN. If the Test Enable signal is active, this signal is used as the Test Input  
data.  
PHYA3  
I/O  
This pin is multiplexed and can be used for one of the following:  
(SLVTRI)  
PHY Address 3. In repeater mode, this signal represents the fourth bit for  
address port configuration.  
Slave Tri-state. In DTE (adapter) mode, this output operates in conjunction  
with the T4 Advanced signal. When both are active, the slave PHY is inactive  
and tri-states all its outputs.  
PHYA2  
(LISTAT)  
6
I
I
This pin is multiplexed and can be used for one of the following:  
PHY Address 2. In repeater mode, this signal represents the third bit for  
address port configuration.  
Link Status. In DTE (adapter) mode, if T4 Advance is active, the LISTAT_N  
signal is active low and the slave PHY link is valid.  
PHYA1  
25  
This pin is multiplexed and can be used for one of the following:  
(TEXEC)  
PHY Address 1. In repeater mode, this signal represents the second bit for  
address port configuration.  
Test Execute. If Test Enable is asserted, this signal acts as the test  
execution command indicating that the pin 22 is being used as the Test Input  
pin.  
PHYA0  
(TCK)  
24  
54  
I
I
This pin is multiplexed and can be used for one of the following:  
PHY Address 0. In repeater mode, this signal represents the first bit for  
address port configuration.  
Test Clock. If Test Enable is asserted, this signal acts as the Test Clock  
signal.  
ANDIS  
This pin is multiplexed and can be used for one of the following:  
(T4ADV)  
Auto-Negotiation Disable. In repeater mode, the Auto-Negotiation operates  
for management reasons. If this input signal is high, the Auto-Negotiation  
operation will be disabled.  
T4ADV. In DTE (adapter) mode, this pin enables the combo mode. This  
allows the LISTAT and SLVTRI pins to be used as interface to the slave PHY.  
SCRMBY 23  
I
I
I
I
Scrambler/Descrambler Bypass. If SCRMBY is high, the scrambler/  
descrambler of TP-PMD will be bypassed.  
LPBK  
2
Loopback. When the LPBK signal is high, the 82555 will perform a  
diagnostic loopback function.  
RPT  
50  
21  
Repeater. When the RPT signal is high, the 82555 functions in repeater  
mode. When this signal is low, the 82555 runs in DTE (adapter) mode.  
TESTEN  
Test. If the TESTEN signal is high, the 82555 enables the test ports.  
Datasheet  
11  
 
82555 — Networking Silicon  
3.9  
Power and Ground Pins  
Symbol  
Pin  
Type  
Name and Function  
Power: +5 V ± 5%  
VCC  
7, 9, 15, 17, 19, 27, 29, 31, 36, 38, 40, 45, 58, 62,  
64, 66, 73, 75, 83, 88, 93, 98  
I
I
VSS  
3, 8, 10, 14, 16, 18, 20, 26, 28, 30, 32, 35, 37, 39,  
41, 46, 49, 53, 57, 61, 63, 65, 67, 72, 74, 78, 84, 89,  
91, 94, 99  
Ground: 0 V  
12  
Datasheet  
 
Networking Silicon — 82555  
4.0  
100BASE-TX Adapter Mode Operation  
4.1  
100BASE-TX Transmit Clock Generation  
A 25 MHz crystal or a 25 MHz oscillator is used to drive the 82555’s X1 and X2 pins. The 82555  
derives its internal transmit digital clocks from this crystal or oscillator input. The Transmit Clock  
signal is a derivative of the 25 MHz internal clock. The accuracy of the external crystal or oscillator  
must be ± 0.0005% (50 PPM).  
4.2  
100BASE-TX Transmit Blocks  
The transmit subsection of the 82555 accepts nibble-wide data on the TXD[3:0] lines when TXEN  
is asserted (high). The transmit subsection passes data unconditionally to the 4B/5B encoder as  
long as TXEN is active.  
The 4B/5B encoder accepts nibble-wide data (4 bits) from the MAC and compiles it into 5-bit-wide  
parallel symbols. These symbols are scrambled and serialized into a 125 Mbps bit stream,  
converted by the analog transmit driver into a MLT-3 waveform format, and transmitted onto the  
Unshielded Twisted Pair (UTP) or Shielded Twisted Pair (STP) wire.  
4.2.1  
100BASE-TX 4B/5B Encoder  
The 4B/5B encoder complies with the IEEE 802.3u 100BASE-TX standard. Four bits are encoded  
according to the transmit 4B/5B lookup table. The lookup table matches a 5-bit code to each 4-bit  
code.  
The table below illustrates the 4B/5B encoding scheme associated with the given symbol.  
Table 2. 4B/5B Encoder  
Symbol  
5B Symbol Code  
4B Nibble Code  
0
1
2
3
4
5
6
7
8
9
A
B
C
D
11110  
01001  
10100  
10101  
01010  
01011  
01110  
01111  
10010  
10011  
10110  
10111  
11010  
11011  
0000  
0001  
0010  
0011  
0100  
0101  
0110  
0111  
1000  
1001  
1010  
1011  
1100  
1101  
Datasheet  
13  
 
82555 — Networking Silicon  
Table 2. 4B/5B Encoder  
Symbol  
5B Symbol Code  
4B Nibble Code  
E
F
11100  
11101  
1110  
1111  
Inter Packet Idle Symbol  
(No 4B)  
I
11111  
11000  
1st Start of Packet Symbol  
0101  
J
2nd Start of Packet Symbol  
0101  
K
T
10001  
01101  
00111  
1st End of Packet Symbol  
2nd End of Packet Symbol  
and Flow Control  
R
V
V
V
V
H
V
V
V
V
V
V
00000  
00001  
00010  
00011  
00100  
00101  
00110  
01000  
01100  
10000  
11001  
INVALID  
INVALID  
INVALID  
INVALID  
INVALID  
INVALID  
INVALID  
INVALID  
INVALID  
Flow Control S  
INVALID  
4.2.2  
100BASE-TX Scrambler and MLT-3 Encoder  
Data is scrambled in 100BASE-TX in order to reduce electromagnetic emissions during long  
transmissions of high-frequency data codes. The scrambler logic accepts 5 bits from the 4B/5B  
encoder block and presents the scrambled data to the MLT-3 encoder. The 82555 implements the  
11-bit stream cipher scrambler as adopted by the ANSI XT3T9.5 committee for UTP operation.  
The cipher equation used is:  
X[n] = X[n-11] + X[n-9] (mod 2)  
The MLT-3 encoder receives the scrambled Non-Return to Zero (NRZ) data stream from the  
scrambler and encodes the stream into MLT-3 for presentation to the driver. MLT-3 is similar to  
NRZI coding, but three levels are output instead of two. There are three output levels: positive,  
negative and zero. When an NRZ “0” arrives at the input of the encoder, the last output level is  
14  
Datasheet  
 
Networking Silicon — 82555  
maintained (either positive, negative or zero). When an NRZ “1” arrives at the input of the encoder,  
the output steps to the next level. The order of steps is negative-zero-positive-zero which continues  
periodically. The figure below illustrates this process.  
Clock  
1
1
0
0
1
0
0
1
NRZ  
1
1
1
1
0
0
0
0
1
1
0
0
0
0
1
1
NRZ1  
MLT-3  
Figure 6. NRZ to MLT-3 Encoding Diagram  
4.2.3  
100BASE-TX Transmit Framing  
The 82555 does not differentiate between the fields of the MAC frame containing preamble, start  
of frame delimiter, data and Cyclic Redundancy Check (CRC). When TXEN is asserted, the 82555  
accepts data on the MII TXD[3:0] lines, encodes it, and sends it out onto the wire. The 82555  
encodes the first byte of the preamble as the “JK” symbol, encodes all other pieces of data  
according to the 4B/5B lookup table, and adds the “TR” code after the end of the packet (de-  
assertion of TXEN). The 82555 scrambles and serializes the data into a 125 Mbps stream, encodes  
it as MLT-3, and drives it onto the wire. If TXERR is asserted during transmission of valid data, the  
82555 transmits an invalid “H” symbol.  
Datasheet  
15  
 
82555 — Networking Silicon  
4.2.4  
Transmit Driver  
The transmit differential lines are implemented with a digital slope controlled current driver that  
meets the TP-PMD specifications. Current is sunk from the isolation transformer by the transmit  
differential pins. The conceptual transmit differential waveform for 100 Mbps is illustrated in the  
following figure.  
(VTDP -VTDN  
)
+1V  
0V  
t
-1V  
ITDP  
40mA  
20mA  
0
t
ITDN  
40mA  
20mA  
0
t
Figure 7. Conceptual Transmit Differential Waveform  
The magnetics module that is external to the 82555 converts ITDP and ITDN to 2.0 Vpp, as required  
by the TP-PMD specification. The same magnetics used for 100BASE-TX mode should also work  
in 10BASE-T mode. The following is a list of current magnetics modules available from several  
vendors:  
Table 3. Magnetics Modules  
Vendor  
Model/Type  
100BASE-TX  
10BASE-T  
Delta  
LF8200A  
PE-68515  
H1012  
Yes  
Yes  
Yes  
Yes  
Yes  
Yes  
Pulse Engineering  
Pulse Engineering  
4.3  
100BASE-TX Receive Blocks  
The receive subsection of the 82555 accepts 100BASE-TX MLT-3 data on the receive differential  
pair. Due to the advanced digital signal processing design techniques employed, the 82555 will  
accurately receive valid data from Category 5 (CAT5) UTP and Type 1 STP cable of length well in  
excess of 100 meters.  
16  
Datasheet  
 
Networking Silicon — 82555  
4.3.1  
4.3.2  
4.3.3  
Adaptive Equalizer  
The distorted MLT-3 signal at the end of the wire is restored by the equalizer. The equalizer  
performs adaptation based on the shape of the received signal, equalizing the signal to meet  
superior Data Dependent Jitter performance.  
Receive Clock and Data Recovery  
The clock recovery circuit uses advanced digital signal processing technology to compensate for  
various signal jitter causes. The circuit recovers the 125 MHz clock and data and presents the data  
to the MLT-3 decoder.  
MLT-3 Decoder, Descrambler, and Receive Digital Section  
The 82555 first decodes the MLT-3 data; afterwards, the descrambler reproduces the 5B symbols  
originated in the transmitter. The descrambling is based on synchronization to the transmit 11-bit  
Linear Feedback Shift Register (LFSR) during idle. The data is decoded at the 4B/5B decoder.  
Once the 4B symbols are obtained, the 82555 outputs the receive data to the CSMA unit.  
4.3.4  
100BASE-TX Receive Framing  
The 82555 does not differentiate between the fields of the MAC frame containing preamble, start  
of frame delimiter, data and CRC. During 100 Mbps reception, the 82555 differentiates between  
the idle condition ("L" symbols on the wire) and the preamble or start of frame delimiter. When  
two non-consecutive bits are 0b within 10 bits (125 Mbps 5B data coding) the 82555 immediately  
asserts the CRS signal. When the “JK” symbols (“11000, 10001”) are fully recognized, the 82555  
asserts the RXDV signal and provides the data received on the MII RXD[3:0] to the Receive Clock.  
If the “JK” symbol is not recognized (“false carrier sense”), the CRS signal is immediately de-  
asserted and RXERR is asserted. Otherwise, the valid data is passed through the MII until the  
82555 finds the “TR” (“01101, 00111”) and idle symbols in order to de-assert TXDV and CRS.  
4.3.5  
100BASE-TX Receive Error Detection and Reporting  
In 100BASE-TX mode, the 82555 can detect errors in receive data in a number of ways. Any of the  
following conditions is considered an error:  
• Link integrity fails in the middle of frame reception.  
• The start of stream delimiter “JK” symbol is not fully detected after idle.  
• An invalid symbol is detected at the 4B/5B decoder.  
• Idle is detected in the middle of a frame (before “TR” is detected).  
When any of the above error conditions occurs, the 82555 immediately asserts the Receive Error  
signal to the MAC. The RXERR signal is asserted as long as the receive error condition persists on  
the receive pair.  
4.4  
100BASE-TX Collision Detection  
100BASE-TX collisions in half duplex mode only are detected similarly to 10BASE-T collision  
detection, via simultaneous transmission and reception.  
Datasheet  
17  
 
82555 — Networking Silicon  
4.5  
100BASE-TX Link Integrity and Auto-Negotiation Solution  
The 82555’s Auto-Negotiation function automatically configures the device to the technology,  
media, and speed to operate with its link partner. Auto-Negotiation is widely described in IEEE  
specification 802.3u, Clause 28. The 82555 supports 10BASE-T half duplex, 10BASE-T full  
duplex, 100BASE-TX half duplex, and 100BASE-TX full duplex.  
The 82555 has two Physical Medium Attachment (PMA) technologies with its link integrity  
function, 10BASE-T and 100BASE-TX. The 82555 also has a special interface defined between  
itself and a PHY-T4 in order to implement an Auto-Negotiation combination card.  
4.5.1  
4.5.2  
Link Integrity  
In 100BASE-TX, the link integrity function is determined by a stable signal status coming from the  
TP-PMD block. Signal status is asserted when the PMD detects breaking squelch energy and the  
right bit error rate according to the ANSI specification.  
Auto-Negotiation  
The 82555 fully supports IEEE 802.3u, Clause 28. In DTE (adapter) mode, the technology,  
10BASE-T or 100BASE-TX, is determined by the Auto-Negotiation result. In repeater mode only,  
this function can be disabled by pin configuration. If the T4ADV pin is active, the Auto-  
Negotiation function will advertise and negotiate T4 technology.  
Speed and duplex auto-select are functions of Auto-Negotiation. However, these parameters may  
be manually configured via the MII management interface (MDI registers).  
4.5.3  
Combination Tx/T4 Auto-Negotiation Solution  
The Auto-Negotiation function is available in both the 82555 and a PHY-T4. For these PHYs to  
operate together, some arbitration at the PMA level is required and the Auto-Negotiation function  
of one of the PHYs must be disabled. For this purpose, the 82555 is defined as the master; and the  
PHY-T4, the slave. In combination mode, only the 82555’s Auto-Negotiation function is enabled  
(the PHY-T4’s Auto-Negotiation is disabled).  
In a combination board, a PHY-T4 is used only to support 100BASE-T4 operation and the 82555 is  
sued to support 100BASE-TX full or half duplex and 10BASE-T full or half duplex as determined  
by the Auto-Negotiation or Parallel Detection function.  
Combination mode is available only in DTE (adapter) mode with the following pin interface:  
• T4ADV (pin 54): Enables T4 technology in a PHY-TX Auto-Negotiation system.  
• SLVTRI (pin 52): Disables the PHY-T4.The PHY-T4 is enabled only if the T4 technology has  
been detected by Auto-Negotiation or Parallel Detection.  
• LISTAT (pin 6): Indicates valid link on the PHY-T4. When SLVTRI is de-asserted, the PHY-  
T4 should be active.  
18  
Datasheet  
 
Networking Silicon — 82555  
The figure below illustrates an 82557/82555/PHY-T4 solution in a block diagram.  
T4  
a d v  
82555  
Co m m o n  
Ma g ne tic s  
fd x_n  
PCI BUS  
MII  
82557  
PHY-T4  
3669  
Figure 8. Combination Card Example  
4.6  
Auto 10/100 Mbps Speed Selection  
The MAC may either allow the 82555 to automatically select its operating speed or force the 82555  
into 10 Mbps or 100 Mbps mode. The Management Data Interface (MDI) can control the 82555  
speed mode.  
The 82555 autoselect function determines the operation speed of the media based on the link  
integrity pulses it receives. If no Fast Link Pulses (FLPs) are detected and Normal Link Pulses  
(NLPs) are detected, the 82555 defaults to 10 Mbps operation. If the 82555 detects a speed change,  
it dynamically changes its transmit clock and receive clock frequencies to the appropriate value.  
This change takes a maximum of five milliseconds.  
4.7  
Adapter Mode Addresses  
In DTE (adapter) mode, the 82555 supports addresses 0, 1, 2, and 3 through the pins PHYA1 and  
PHYA0. Four addresses are sufficient in the case of a combination adapter having three PHYs. For  
switch applications, the T4ADV signal should be de-asserted to allow all 32 addresses to be  
available in repeater mode.  
Datasheet  
19  
 
82555 — Networking Silicon  
20  
Datasheet  
 
Networking Silicon — 82555  
5.0  
10BASE-T Functionality in Adapter Mode  
5.1  
10BASE-T Transmit Clock Generation  
The 20 MHz and 10 MHz clocks needed for 10BASE-T are synthesized from the external 25 MHz  
crystal or oscillator. The 82555 provides the transmit clock and receive clock to the MAC at 2.5  
MHz.  
5.2  
10BASE-T Transmit Blocks  
5.2.1  
10BASE-T Manchester Encoder  
After the 2.5 MHz clocked data is serialized in a 10 Mbps serial stream, the 20 MHz clock  
performs the Manchester encoding. The Manchester code always has a mid-bit transition. If the  
value is 1b then the transition is from low to high. If the value is 0b then the transition is from high  
to low. The boundary transition occurs only when the data changes from bit to bit. For example, if  
the value is 10b, then the change is from high to low; if 01b, then the change is from low to high.  
5.2.2  
10BASE-T Driver and Filter  
Since 10BASE-T and 100BASE-TX have different filtration needs, both filters are implemented  
inside the chip. This allows the two technologies to share the same magnetics. The 82555 supports  
both technologies through one pair of transmit differential pins and by externally sharing the same  
magnetics.  
In 10 Mbps mode, the 82555 begins transmitting the serial Manchester bit stream within 3 bit times  
(300 nanoseconds) after the MAC asserts TXEN. In 10 Mbps mode the line drivers use a pre-  
distortion algorithm to improve jitter tolerance. The line drivers reduce their drive level during the  
second half of “wide” (100 ns) Manchester pulses and maintain a full drive level during all narrow  
(50 ns) pulses and the first half of the wide pulses. This reduces line overcharging during wide  
pulses, a major source of jitter.  
5.3  
10BASE-T Receive Blocks  
5.3.1  
10BASE-T Manchester Decoder  
The 82555 performs Manchester decoding and timing recovery when in 10 Mbps mode. The  
Manchester encoded data stream is decoded from the receive differential pair to separate Receive  
Clock and Receive Data lines from the differential signal. This data is transferred to the controller  
at 2.5 MHz/nibble through the MII. The high-performance circuitry of the 82555 exceeds the IEEE  
802.3 jitter requirements.  
5.3.2  
10BASE-T Twisted Pair Ethernet (TPE) Receive Buffer and Filter  
In 10 Mbps mode, data is expected to be received on the receive differential pair after passing  
through isolation transformers. The filter is implemented inside the 82555 for supporting single  
magnetics that are shared with the 100BASE-TX side. The input differential voltage range for the  
Datasheet  
21  
 
82555 — Networking Silicon  
Twisted Pair Ethernet (TPE) receiver is greater than 585 mV and less than 3.1 V. The TPE receive  
buffer distinguishes valid receive data, link test pulses, and the idle condition, according to the  
requirements of the 10BASE-T standard.  
The following line activity is determined to be inactive and is rejected:  
• Differential pulses of peak magnitude less than 300 mV.  
• Continuous sinusoids with a differential amplitude less than 6.2 Vpp and frequency less than 2  
MHz.  
• Sine waves of a single cycle duration starting with 0° or 180° phase that have a differential  
amplitude less than 6.2 Vpp and a frequency of at least 2 MHz and not more than 16 MHz.  
These single-cycle sine waves are discarded only if they are preceded by 4 bit times (400  
nanoseconds) of silence.  
All other activity is determined to be either data, link test pulses, Auto-Negotiation fast link pulses,  
or the idle condition. When activity is detected, the carrier sense signal is asserted to the MAC.  
5.3.3  
10BASE-T Error Detection and Reporting  
In 10 Mbps mode, the 82555 can detect errors in the receive data. The following condition is  
considered an error:  
The receive pair’s voltage level drops to the idle state during reception before the end-of-frame  
bit is detected (250 nanoseconds without mid-bit transitions).  
5.4  
5.5  
10BASE-T Collision Detection  
Collision detection in 10 Mbps mode is indicated by simultaneous transmission and reception. If  
the 82555 detects this condition, it asserts a collision indication to the controller.  
10BASE-T Link Integrity  
The link integrity in 10 Mbps works with link pulses. The 82555 senses and differentiates those  
link pulses from fast link pulses and from 100BASE-TX idles. In the first and last case, the 82555  
activates parallel detection of the respective technology; and in the second case, Auto-Negotiation.  
The 10 Mbps link pulses or normal link pulses are driven in the transmit differential pair line but  
are 100 ns wide and have levels from 0 V to 5 V. The link beat pulse is also used to determine if the  
receive pair polarity is reversed. If it is, the polarity is corrected internally.  
5.6  
10BASE-T Jabber Control Function  
The 82555 contains a jabber control function that inhibits transmission after a specified time  
window when enabled. In 10 Mbps mode, the jabber timer is set to a value between 26.2 ms and 39  
ms. If the 82555 detects continuous transmission that is greater than this time period, it prevents  
further transmissions from onto the wire until it detects that the MAC transmit enable signal has  
been inactive for at least 314 ms.  
22  
Datasheet  
 
Networking Silicon — 82555  
5.7  
10BASE-T Full Duplex  
The 82555 supports 10 Mbps full duplex by disabling the collision function, the squelch test, and  
the carrier sense transmit function. This allows the 82555 to transmit and receive simultaneously,  
achieving up to 20 Mbps of network bandwidth. The configuration can be achieved through Auto-  
Negotiation. Full duplex should only be used in point-to-point connections (no shared media).  
Flow control is always disabled.  
Datasheet  
23  
 
82555 — Networking Silicon  
24  
Datasheet  
 
Networking Silicon — 82555  
6.0  
Repeater Mode  
The 82555 has a compete set of repeater features making it the ideal PHY for Class 1 (MII)  
repeater designs. The 82555 works in repeater mode when the RPT signal (pin 50) is high. The  
FRC100 signal (pin 51) determines which type of repeater is supported, either 100BASE-TX or  
10BASE-T.  
6.1  
Special Repeater Features  
Special features of the 82555 repeater mode operation include:  
• Fully IEEE compliant with automatic carrier disconnect.  
The 82555 will disconnect when it receives false carrier detects. Either a long series of valid  
idle symbols or a valid “JK” pair will cause it to reconnect.  
• Narrow 14 mm analog side that enables tight packing of multiple PHYs, which is ideal for 8,  
12, 18, 24, or even 32 port repeater designs.  
• Very low emissions and high noise immunity.  
• 32 configurable addresses through five address lines.  
• Auto-Negotiation disable function.  
In repeater mode, the Auto-Negotiation function is not used for configuration purposes. When  
Auto-Negotiation is enabled in repeater mode, the MII management will be able to obtain data  
from the MDI Auto-Negotiation register about the remote partner. This is a feature for hub  
management allowing a 10/100 Mbps repeater design to automatically detect whether or not it  
can operate at 100 Mbps. If the ANDIS signal is de-asserted, the Auto-Negotiation feature will  
be disabled.  
• Forced 10 Mbps or 100 Mbps operation (allows for a 10/100 repeater design).  
• Receive port enable function.  
The PORTEN signal is a glueless interface to the Repeater Interface Controller (RIC). When  
the PORTEN signal is low, all receive signals are tri-stated, except CRS and COL.  
• 26-bit PHY budget for round trip.  
The total PHY bit budget is 8 bits from the MII to the wire and 18 bits from the wire to the  
MII.  
• Static 2.5 MHz (10BASE-T) or 25 MHz (100BASE-TX) clock input for repeater designs  
(issued by RIC).  
The 82555 clock source is fixed between Resets. There is one input, either 2.5 MHz or 25  
MHz, as indicated by the level at the FRC100 pin. All clocks have a common source  
generation so the that PPM is 0 between them (X1, 2.5 MHz and 25 MHz).  
• DTE (adapter) features not available in repeater mode: full duplex, flow control, and the  
combination Auto-Negotiation interface for T4.  
6.2  
Connectivity  
A 25 MHz buffered oscillator can provide the clock to all of the 82555 devices. A 2.5 MHz (10  
Mbps) or a 25 MHz (100 Mbps) signal is required to clock the RIC and the TXC signal in the  
PHYs. TXD[3:0], TXERR, RXC, RXD[3:0], RXDV, and RXERR are single-bus (shortened) for all  
Datasheet  
25  
 
82555 — Networking Silicon  
PHYs connected to the RIC. Signals TXEN, CRS, and PORTEN are connected from each of the  
82555 devices to the specified RIC pin. The figure below illustrates an example of multiple 82555s  
connected to a 25 MHz (or 2.5 MHz) oscillator.  
RIC  
CLK  
2.5/25 MHz (10/100)  
TXCLK  
TXCLK  
PHY2  
X1  
TXCLK  
PHY3  
X1  
PHY1  
2.5/25 MHz (10/100)  
X1  
PC-3691  
Figure 9. Clock Signal Example  
26  
Datasheet  
 
Networking Silicon — 82555  
7.0  
Management Data Interface  
The 82555 provides status and accepts management information through the Management Data  
Interface (MDI). This is accomplished through read and write operations to various registers in  
accordance with the IEEE 802.3u MII specification.  
7.1  
MDI Frame Structure  
Data read from or written to a particular register is called a management frame and is sent serially  
over the MDIO pin synchronously to the MDC signal. Read and write cycles are viewed from the  
perspective of the controller. Thus, the controller always drives the start, opcode, PHY address, and  
register address onto the MDIO pin. For read cycles, the controller drives the transition bits and  
data onto the MDIO pin; for write cycles, to the 82555. The controller drives addresses and data on  
the falling edge of the MDC signal, and the 82555 latches the data on the rising edge of the MDC  
signal. The following list defines protocol terms:  
PREAMBLE At the beginning of each transaction, the controller send a sequence of 32  
contiguous logic one bits on the MDIO pin with corresponding cycles on the MDC  
pin for synchronization by the 82555.  
ST  
OP  
This field contains the value of 01b indicating the start of a frame.  
This is a 2-bit field containing one of the following two operation codes: 10b (read)  
or 01b (write).  
PHYAD  
REGAD  
TA  
This field is a 5-bit address of the 82555 device that provides support for 32 unique  
PHY addresses. The controller drives the value written into the PHYAD portion of  
the MDI register in this field.  
This field is a 5-bit address of a specific register within the 82555. This provides  
support for 32 unique registers. The desired register address is specified by the  
value written to the MDI register.  
This field contains a 2-bit value specifying the period during a read cycle that no  
device may actively drive the MDIO signal. During a read transaction, the 82555  
should not drive the MDIO signal in the first bit time; however, it will drive a 0b in  
the second bit time. During a write transaction, the controller drives the pattern of  
10b to fill this time.  
DATA  
IDLE  
This field contains 16 bits of data driven by the 82555 on a read transaction or by  
the controller on a write transactions. This data is either control or status parameters  
passed between the controller and the 82555.  
During the idle state, the MDIO signal is in a high impedance state. The MDIO  
driver is disabled, and the 82555 will pull the MDIO signal high to a logic 1.  
Datasheet  
27  
 
82555 — Networking Silicon  
The 82555 address can be configured to four 0 through 3 in DTE (adapter) mode and 0 through 31  
in repeater mode. A special functions for switches allows 32 addresses to exist in repeater mode.  
The management frame structure is as follows:  
Transition  
ST  
OP  
PHYAD  
REGAD  
TA  
DATA  
READ  
<01>  
<01>  
<10>  
<01>  
<AAAAA>  
<AAAAA>  
<RRRRR>  
<RRRRR>  
<X0>  
<10>  
16 bits  
16 bits  
WRITE  
7.2  
MDI Registers  
MDI registers are described in the following subsections and the acronyms mentioned in the  
registers are defined as follows:  
SC - Self Cleared.  
RO -Read Only.  
P- External pin affects 82555 register content.  
LL - Latch Low.  
LH - Latch High.  
7.2.1  
MDI Registers 0 - 7  
7.2.1.1  
Register 0: Control Register Bit Definitions  
Bit(s)  
15  
Name  
Description  
Default R/W  
Reset  
This bit sets the status and control register of the 82555  
to their default states and is self-clearing. The PHY  
returns a value of 1b until the reset process has  
completed and accepts a read or write transaction.  
0
RW  
SC  
1 = PHY Reset  
0 = Normal operation  
14  
Loopback  
This bit enables loopback of transmit data nibbles from  
the TXD[3:0] signals to the receive data path. The  
82555’s receive circuitry is isolated from the network.  
0
RW  
P
Note that this may cause the descrambler to lose  
synchronization and produce 560 nanoseconds of “dead  
time.”  
Note also that the loopback configuration bit takes priority  
over the Loopback MDI bit.  
1 = Loopback enabled  
0 = Loopback disabled (normal operation)  
13  
12  
Speed Selection  
This bit controls speed when Auto-Negotiation is disabled  
and is valid on read when Auto-Negotiation is disabled.  
1
1
RW  
P
1 = 100 Mbps  
0 = 10 Mbps  
Auto-Negotiation  
Enable  
This bit enables Auto-Negotiation. Bits 13 and 8, Speed  
Selection and Duplex Mode, respectively, are ignored  
when Auto-Negotiation is enabled.  
RW  
1 = Auto-Negotiation enabled  
0 = Auto-Negotiation disabled  
28  
Datasheet  
 
Networking Silicon — 82555  
Bit(s)  
11  
Name  
Description  
Default R/W  
Power-Down  
This bit sets the 82555 into a low power mode.  
1 = Power-down enabled  
0
RW  
0 = Power-down disabled (normal operation)  
10  
Isolate  
This bit allows the 82555 to electrically isolate the Media  
Independent Interface. When the MII is isolated, the  
82555 does not respond to TXD[3:0], TXEN, and TXERR  
input signals. Also, the 82555 presents high impedance  
on its TXC, RXC, RXDV, RXERR, RXD[3:0], COL, and  
CRS output signals. In the TX mode, the 82555 responds  
to management transactions.  
0
RW  
1 = Electrically isolate MII  
0 = Normal operation  
9
8
Restart Auto-  
Negotiation  
This bit restarts the Auto-Negotiation process and is self-  
clearing.  
0
0
RW  
SC  
1 = Restart Auto-Negotiation process  
0 = Normal operation  
Duplex Mode  
This bit controls the duplex mode when Auto-Negotiation  
is disabled. If the 82555 reports that it is only able to  
operate in one duplex mode, the value of this bit shall  
correspond to the mode which the 82555 can operate.  
RW  
When the 82555 is placed in Loopback mode, the  
behavior of the PHY shall not be affected by the status of  
this bit, bit 8.  
1 = Full Duplex  
0 = Half Duplex  
7
Collision Test  
Reserved  
This bit will force a collision in response to the assertion  
of the transmit enable signal.  
0
0
RW  
RW  
1 = Force COL  
0 = Do not force COL  
6:0  
These bits are reserved and should be set to 0000000b.  
7.2.1.2  
Register 1: Status Register Bit Definitions  
Bit(s)  
15  
Name  
Description  
Default  
R/W  
RO  
100BASE-T4  
1 = 82555 able to perform 100BASE-T4  
0 = 82555 not able to perform 100BASE-T4  
--  
P
14  
100BASE-TX Full 1 = 82555 able to perform full duplex 100BASE-TX  
--  
RO  
P
Duplex  
0 = 82555 not able to perform full duplex in repeater  
mode  
13  
12  
100 Mbps Half  
Duplex  
1 = 82555 able to perform half duplex 100BASE-TX  
0 = 82555 not able to perform 100BASE-TX  
--  
--  
RO  
P
10 Mbps Full  
Duplex  
1 = 82555 able to operate at 10 Mbps in full duplex  
mode  
RO  
P
0 = 82555 not able to operate in full duplex mode in  
10BASE-T  
11  
10 Mbps Half  
Duplex  
1 = 82555 able to operate at 10 Mbps in half duplex  
mode  
--  
0
RO  
P
0 = 82555 not able to operate in 10BASE-T  
10:7  
Reserved  
These bits are reserved and should be set to 0000b.  
RO  
Datasheet  
29  
 
82555 — Networking Silicon  
Bit(s)  
Name  
Management  
Description  
Default  
R/W  
RO  
6
1 = 82555 will accept management frames with  
--  
Frames Preamble preamble suppressed  
Suppression  
0 = 82555 will not accept management frames with  
preamble suppressed  
5
4
3
Auto-Negotiation  
Complete  
1 = Auto-Negotiation process completed  
0
0
1
RO  
0 = Auto-Negotiation process has not completed  
Remote Fault  
1 = Remote fault condition detected  
0 = No remote fault condition detected  
RO  
P
Auto-Negotiation  
Ability  
1 = 82555 is able to perform Auto-Negotiation  
RO  
0 = 82555 is in repeater mode and Auto-Negotiation  
Disable pin is high  
2
1
0
Link Status  
1 = Valid link has been established  
0 = Invalid link detected  
0
0
1
RO  
LL  
SC  
Jabber Detect  
1 = Jabber condition detected  
0 = No jabber condition detected  
RO  
LH  
SC  
Extended  
Capability  
1 = Extended register capabilities enabled  
0 = No extended register capabilities  
RO  
7.2.1.3  
7.2.1.4  
7.2.1.5  
Register 2: 82555 Identifier Register Bit Definitions  
Bit(s)  
Name  
Description  
Default  
R/W  
RO  
15:0  
82555 ID (high  
byte)  
Value: 02A8H  
--  
Register 3: 82555 Identifier Register Bit Definitions  
Bit(s)  
Name  
Description  
Default  
R/W  
RO  
15:0  
82555 ID (low  
byte)  
Value: 0150H  
--  
Register 4: Auto-Negotiation Advertisement Register Bit Definitions  
Bit(s)  
15  
Name  
Next Page  
Description  
Default  
R/W  
Constant 0 = Transmitting primary capability data  
page  
--  
RO  
14  
13  
Reserved  
This bit is reserved and should be set to 0b.  
0
0
RO  
Remote Fault  
1 = Indicate link partner’s remote fault  
0 = No remote fault  
RW  
12:5  
4:0  
Technology Ability Technology Ability Field is an 8-bit field containing  
--  
RW  
RO  
Field  
information indicating supported technologies specific  
to the selector field value.  
Selector Field  
The Selector Field is a 5-bit field identifying the type of  
message to be sent via Auto-Negotiation. This field is  
read only in the 82555 and contains a value of  
00001b, IEEE Standard 802.3.  
00001  
30  
Datasheet  
 
Networking Silicon — 82555  
7.2.1.6  
Register 5: Auto-Negotiation Link Partner Ability Register Bit Definitions  
Bit(s)  
15  
Name  
Next Page  
Description  
Default  
R/W  
RO  
This bit reflects the 82555’s link partner’s Auto-  
Negotiation ability.  
--  
14  
Acknowledge  
Remote Fault  
This bit is used to indicate that the 82555 has  
successfully received its link partner’s Auto-  
Negotiation advertising ability.  
--  
RO  
13  
This bit reflects the 82555’s link partner’s Auto-  
Negotiation ability.  
--  
--  
--  
RO  
RO  
RO  
12:5  
4:0  
TechnologyAbility This bit reflects the 82555’s link partner’s Auto-  
Field  
Negotiation ability.  
Selector Field  
This bit reflects the 82555’s link partner’s Auto-  
Negotiation ability.  
7.2.1.7  
Register 6: Auto-Negotiation Expansion Register Bit Definitions  
Bit(s)  
Name  
Reserved  
Description  
Default  
R/W  
15:5  
These bits are reserved and should be set to a  
constant 0.  
0
RO  
4
Parallel Detection 1 = Fault detected via parallel detection (multiple link  
0
RO  
SC  
LH  
Fault  
fault occurred)  
0 = No fault detected via parallel detection  
This bit will self-clear on read  
3
2
1
Link Partner Next 1 = Link Partner is Next Page able  
0
0
0
RO  
RO  
page Able  
0 = Link Partner is not Next Page able  
Next Page Able  
Page Received  
1 = Local drive is Next Page able  
0 = Local drive is not Next Page able  
1 = New Page received  
RO  
SC  
LH  
0 = New Page not received  
This bit will self-clear on read.  
0
Link Partner Auto- 1 = Link Partner is Auto-Negotiation able  
0
RO  
Negotiation Able  
0 = Link Partner is not Auto-Negotiation able  
7.2.2  
7.2.3  
MDI Registers 8 - 15  
Registers eight through fifteen are reserved for IEEE.  
MDI Registers 16 - 31  
Register numbers 16, 17, 20, 21, 22, 23, 24, 25, and 27 are described in the following subsections.  
Datasheet  
31  
 
82555 — Networking Silicon  
7.2.3.1  
Register 16: 82555 Status and Control Register Bit Definitions  
Bit(s)  
15  
Name  
Description  
Default  
R/W  
RW  
Flow Control  
This bit enables PHY Base (Bay Technologies) flow  
control.  
0
1 = Enable PHY Base flow control  
0 = Disable PHY Base flow control  
14  
13  
Reserved  
These bits are reserved and should be set to 0b  
0
RW  
RW  
Carrier Sense  
Disconnect  
Control  
This bit enables the disconnect function.  
0 (DTE  
1 (Rptr)  
1 = Disconnect function enabled (default in DTE)  
0 = Disconnect function disabled (default in repeater)  
12  
Transmit Flow  
Control Disable  
This bit enables Transmit Flow Control  
1 = Transmit Flow Control enabled  
0 = Transmit Flow Control disabled  
0
RW  
11  
10  
Receive De-  
Serializer In-Sync De-Serializer In-Sync.  
Indication  
This bit indicates status of the 100BASE-TX Receive  
--  
--  
RO  
RO  
100BASE-TX  
Power-Down  
This bit indicates the power state of 100BASE-TX  
82555.  
1 = Power-down  
0 = Normal operation  
9
8
10BASE-T  
Power-Down  
This bit indicates the power state of 10BASE-TX  
82555.  
--  
--  
RO  
RO  
1 = Power-Down  
0 = Normal operation  
Polarity  
This bit indicates 10BASE-T polarity.  
1 = Reverse polarity  
0 = Normal polarity  
7:3  
2
Reserved  
T4  
These bits are reserved and should be set to a  
constant 0.  
00000  
--  
RO  
RO  
This bit indicates the Auto-Negotiation result.  
1 = 100BASE-T4  
0 = No 100BASE-T4  
1
0
Speed  
This bit indicates the Auto-Negotiation result.  
1 = 100 Mbps  
--  
--  
RO  
RO  
0 = 10 Mbps  
Duplex Mode  
This bit indicates the Auto-Negotiation result.  
1 = Full Duplex  
0 = Half Duplex  
7.2.3.2  
Register 17: 82555 Special Control Bit Definitions  
Bit(s)  
15  
Name  
Description  
1 = By-pass Scrambler  
Default  
R/W  
Scrambler By-  
pass  
0
RW  
0 = Normal operations  
14  
By-pass 4B/5B  
1 = 4 bit to 5 bit by-pass  
0 = Normal operation  
0
RW  
32  
Datasheet  
 
Networking Silicon — 82555  
Bit(s)  
13  
Name  
Description  
Default  
R/W  
RW  
Force Transmit H- 1 = Force transmit H-pattern  
0
Pattern  
0 = Normal operation  
12  
11  
Force 34 Transmit 1 = Force 34 transmit pattern  
0
0
RW  
RW  
Pattern  
0 = Normal operation  
Good Link  
1 = 100BASE-TX link good  
0 = Normal operation  
10  
9
Reserved  
This bit is reserved and should be set to 0b.  
0
0
RW  
RW  
Transmit Carrier  
Sense Disable  
1 = Transmit Carrier Sense disabled  
0 = Transmit Carrier Sense enabled  
8
7
6
5
4
3
2
1
0
Disable Dynamic  
Power-Down  
1 = Dynamic Power-Down disabled  
0
0
0
0
0
0
--  
0
0
RW  
RW  
RW  
RW  
RW  
RW  
RW  
RW  
RW  
0 = Dynamic Power-Down enabled (normal)  
Auto-Negotiation  
Loopback  
1 = Auto-Negotiation loopback  
0 = Auto-Negotiation normal mode  
MDI Tri-State  
Filter By-pass  
1 = MDI Tri-state (transmit driver tri-states)  
0 = Normal operation  
1 = By-pass filter  
0 = Normal filter operation  
Auto Polarity  
Disable  
1 = Auto Polarity disabled  
0 = Normal polarity operation  
Squelch Disable  
1 = 10BASE-T squelch test disable  
0 = Normal squelch operation  
Extended  
Squelch  
1 = 10BASE-T Extended Squelch control enabled  
0 = 10BASE-T Extended Squelch control disabled  
Link Integrity  
Disable  
1 = Link disabled  
0 = Normal Link Integrity operation  
Jabber Function  
Disable  
1 = Jabber disabled  
0 = Normal Jabber operation  
7.2.3.3  
Register 20: 100BASE-TX Receive Disconnect Counter Bit Definitions  
Bit(s)  
Name  
Description  
Default  
R/W  
15:0  
Disconnect Event This field contains a 16-bit counter that increments for  
each disconnect event. The counter stops when full  
--  
RO  
SC  
(and does not roll over) and self-clears on read  
In repeater mode, a frame that starts without “JK” is a  
disconnect event.  
7.2.3.4  
Register 21: 100BASE-TX Receive Error Frame Counter Bit Definitions  
Bit(s)  
Name  
Description  
Default  
R/W  
15:0  
Receive Error  
Frame  
This field contains a 16-bit counter that increments  
once per frame for any receive error condition (such  
as a symbol error or premature end of frame) in that  
frame. The counter stops when full (and does not roll  
over) and self-clears on read.  
--  
RO  
SC  
Datasheet  
33  
 
82555 — Networking Silicon  
7.2.3.5  
Register 22: Receive Symbol Error Counter Bit Definitions  
Bit(s)  
Name  
Description  
Default  
R/W  
15:0  
Symbol Error  
Counter  
This field contains a 16-bit counter that increments for  
each symbol error. The counter stops when full (and  
does not roll over) and self-clears on read.  
--  
RO  
SC  
In a frame with a bad symbol, each sequential six bad  
symbols count as one.  
7.2.3.6  
Register 23: 100BASE-TX Receive Premature End of Frame Error Counter  
Bit Definitions  
Bit(s)  
Name  
Description  
Default  
R/W  
15:0  
Premature End of This field contains a 16-bit counter that increments for  
--  
RO  
SC  
Frame  
each premature end of frame event. The counter  
stops when full (and does not roll over) and self-clears  
on read.  
A frame without a “TR” at the end is considered a  
premature end of frame event.  
7.2.3.7  
7.2.3.8  
7.2.3.9  
Register 24: 10BASE-T Receive End of Frame Error Counter Bit Definitions  
Bit(s)  
Name  
Description  
Default  
R/W  
15:0  
End of Frame  
Counter  
This is a 16-bit counter that increments for each end  
of frame error event. The counter stops when full (and  
does not roll over) and self-clears on read.  
--  
RO  
SC  
Register 25: 10BASE-T Transmit Jabber Detect Counter Bit Definitions  
Bit(s)  
Name  
Description  
Default  
R/W  
15:0  
Jabber Detect  
Counter  
This is a 16-bit counter that increments for each  
jabber detection event. The counter stops when full  
(and does not roll over) and self-clears on read.  
--  
RO  
SC  
Register 27: 82555 Special Control Bit Definitions  
Bit(s)  
Name  
Reserved  
Description  
Default  
R/W  
15:3  
2:0  
These bits are reserved and should be set to 0b.  
0
RW  
RW  
LED Switch  
Control  
Value  
000  
001  
010  
011  
100  
101  
110  
111  
ACTLED  
Activity  
Speed  
Speed  
Activity  
Off  
LILED  
Link  
000  
Collision  
Link  
Collision  
Off  
Off  
On  
On  
Off  
On  
On  
34  
Datasheet  
 
Networking Silicon — 82555  
8.0  
Auto-Negotiation Functionality  
The 82555 supports Auto-Negotiation. Auto-Negotiation is a scheme of auto-configuration  
designed to manage interoperability in multifunctional LAN environments. It allows two stations  
with “N” different modes of communication to establish a common mode of operation. At power-  
up, Auto-Negotiation automatically establishes a link that takes advantage of an Auto-Negotiation  
capable device. An Auto-Negotiation capable device can detect and automatically configure its  
port to take maximum advantage of common modes of operation without user intervention or prior  
knowledge by either station. The possible common modes of operation are: 100BASE-TX,  
100BASE-TX Full Duplex, 100BASE-T4, 10BASE-T, and 10BASE-T Full Duplex.  
8.1  
Description  
Auto-Negotiation selects the fastest operating mode (in other words, the highest common  
denominator) available to hardware at both ends of the cable. A PHY’s capability is encoded by  
bursts of link pulses called Fast Link Pulses (FLPs). Connection is established by FLP exchange  
and handshake during link initialization time. Once the link is established by this handshake, the  
native link pulse scheme resumes (that is, 10BASE-T or 100BASE-TX link pulses). A reset or  
management renegotiate command (through the MDI interface) will restart the process. To enable  
Auto-Negotiation, bit 12 of the MDI Control Register must be set. If the 82555 cannot perform  
Auto-Negotiation, it will set this bit to 0b and determine the speed using Parallel Detection.  
The 82555 supports four technologies: 100BASE-Tx Full and Half Duplex and 10BASE-T Full  
and Half Duplex. Since only one technology can be used at a time (after every renegotiate  
command), a prioritization scheme must be used to ensure that the highest common denominator  
ability is chosen. Table 4 lists the technology ability field bit assignments. Each bit in this table is  
set according to what the PHY is capable of supporting. In the case of the 82555, bits 0, 1, 2, and 3  
are set. Table 5 lists the priority of each of the technologies.  
Table 4. Technology Ability Field Bit Assignments  
Bit Setting  
Technology  
0
1
2
3
4
5
6
7
10BASE-T Half Duplex  
10BASE-T Full Duplex  
100BASE-T Half Duplex  
100BASE-T Full Duplex  
100BASE-T4  
Pause (Flow Control)  
Reserved  
Reserved  
Table 5. Technology Priority  
Priority  
Technology  
1
2
3
100BASE-TX Full Duplex  
100BASE-T4  
100BASE-TX Half Duplex  
Datasheet  
35  
 
   
82555 — Networking Silicon  
Table 5. Technology Priority  
Priority  
Technology  
4
5
10BASE-T Full Duplex  
10BASE-T Half Duplex  
To detect the correct technology, the two register fields should be ANDed together to obtain the  
highest common denominator. This value should then be used to map into a priority resolution  
table used by the MAC driver to use the appropriate technology.  
The following is an outline of the Auto-Negotiation process:  
1. Receive 3 consecutive, matching code words  
2. Set Acknowledge bit in transmit code word  
3. Receive 3 consecutive, matching code words with Acknowledge bit set  
4. Transmit 6 to 8 more code words with Acknowledge bit set  
5. Determine operating mode via the priority table  
6. Receive FLP from the link partner and record FLP in the MII register  
8.2  
Parallel Detect and Auto-Negotiation  
The 82555 automatically determines the speed of the link either by using Parallel Detect or Auto-  
Negotiation. Upon a reset, a link status fail, or a negotiate/renegotiate command, the 82555 inserts  
a long delay during which no link pulses are transmitted. This period, known as Force_Fail, insures  
that the 82555’s link partner has gone into a Link Fail state before Auto-Negotiation or Parallel  
Detection begins. Thus, both sides (the 82555 and the 82555’s link partner) will perform Auto-  
36  
Datasheet  
 
Networking Silicon — 82555  
Negotiation or Parallel Detection with no data packets being transmitted. Connection is then  
established either by FLP exchange or Parallel Detection. The 82555 will look for both FLPs and  
link integrity pulses. The following diagram illustrates this process.  
Force_Fail  
Ability detect either by  
parallel detect or auto-  
negotiation.  
Parallel Detection  
Auto-Negotiation  
10Base-T or  
100Base-TX Link  
Ready  
FLP capable  
Look at Link Pulse;  
Auto-Negotiation capable = 0  
Auto-Negotiation capable = 1  
Ability Match  
LINK PASS  
Auto-Negotiation Complete bit set  
Figure 10. Auto-Negotiation and Parallel Detect  
Datasheet  
37  
 
82555 — Networking Silicon  
38  
Datasheet  
 
Networking Silicon — 82555  
9.0  
LED Descriptions  
The 82555 supports four LED pins to indicate link status, network activity and network speed.  
• Link: This LED is off (logic high) until a valid link has been detected. After a valid link has  
been detected, the LED will remain on (active-low).  
• Activity: This LED is on (active-low) when activity is detected on the wire. In DTE (adapter)  
mode, this LED is on during transmit and receive when the 82555 is not in loopback mode. In  
repeater mode, this LED is on only during receive when the 82555 is not in loopback mode.  
• Speed: This LED will be on if a 100BASE-TX link is detected and off if a 10BASE-T link is  
detected. If the link fails while in Auto-Negotiation, this LED will keep the last valid link state.  
If 100BASE-TX link is forced this LED will be on, regardless of the link status. This LED will  
be of if the 10BASE-T link is forced, regardless of the link status.  
• Full Duplex: The FDX_N signal can operate as a LED if it is enabled. It indicates full duplex  
link for either 100BASE-TX or 10 BASE-T technology.  
MDI register 27 in Section 7.2.3.9, “Register 27: 82555 Special Control Bit Definitions” on  
page 34 details the information for LED function mapping and support enhancements.  
Datasheet  
39  
 
82555 — Networking Silicon  
40  
Datasheet  
 
Networking Silicon — 82555  
10.0  
Reset and Miscellaneous Test Modes  
10.1  
Reset  
When the 82555 RESET signal is asserted (high), all internal circuits are reset. TXC and RXC  
should run continuously even though RESET is active. The 82555 may also be reset through the  
MDI reset bit.  
10.2  
10.3  
10.4  
Loopback  
When the loopback pin is being driven high, the 82555 executes a loopback diagnostics operation.  
This mode can also be accessed through the MDI registers.  
Scrambler Bypass  
When the Scrambler Bypass pin is active, the 82555 bypasses the scrambler/descrambler. This  
mode can also be accessed through the MDI registers.  
Test Port  
When the TESTEN pin is high, the test pins provide a test access port for the 82555. In test mode,  
the 82555 will default to address 1. The 82555 has a simple Test Access Port (TAP) from which all  
the test modes are selected and test instructions are operated. The TAP is controlled by a simple  
mechanism and handshake. Activation of all test modes requires simple hardware. The TAP signals  
connected to the 82555 blocks and periphery control the 82555’s mode of operation to allow simple  
testing and internal built-in self testing.  
The test instruction are shifted into the Test Instruction Shift Register (TISR) through the TIN pin.  
The TIN pin is sampled on the rising edge of the TCK input signal. The instruction is transferred  
from the TISR to the Test Instruction Register (TIR) when TESTEN is sampled high on the rising  
edge of TCK. As a general rule, all the TAP input and output pins are activated by the rising edge of  
TCK. If TCK is a constant clock signal, then TESTEN must be 1 clock pulse width.  
When the TIR receives a new instruction, the instruction is decoded into control signals and  
synchronized to the 10 MHz clock. These control signals set the 82555 blocks into various test  
modes. In order to achieve stable synchronization between the clock signal (X1) and the TCK  
signal, the TCK input signal frequency should be less than or equal to half of the clock input signal  
frequency.  
Datasheet  
41  
 
82555 — Networking Silicon  
The TOUT pin is controlled by different sources according to the active test instruction. The TOUT  
signal is activated by the falling edge of TCK. The TAP must be reset during power-up. Otherwise,  
the 82555 can wake-up during high-Z mode or NAND Test, which can be harmful to the board.  
The TAP should be reset only with a hardware reset input pin and not with software reset. The  
TOUT control logic selects the TISR output in all tests, except burn-in test modes.  
Table 6. Test Instruction Coding  
Number  
Code  
Test Instruction  
Select Input to TOUT  
1
2
3
4
00000  
00001  
00010  
00011  
Idle  
TISR D4out  
TISR D4out  
High-Z  
Reserved  
High-Z  
NAND Test  
TISR D4out  
42  
Datasheet  
 
Networking Silicon — 82555  
Electrical Specifications and Timing Parameters  
Absolute Maximum Ratings  
11.0  
11.1  
Symbol  
Parameter Description  
Min  
Typ  
Max  
Units  
T
Case temperature under bias  
Storage temperature  
Supply voltage  
0
85  
140  
7.0  
7.0  
8.0  
6.0  
C
C
V
V
V
V
C
S
T
-65  
-0.5  
-0.5  
-0.5  
-1.0  
V
V
V
V
SUP  
a
All output voltages  
OA  
Transmit Data Output Voltage  
All input voltages  
OTD  
IA  
a. Stresses above the listed under absolute maximum ratings may cause permanent damage to the  
device. This is a stress rating only and functional operations of the device at these or any other  
conditions above those indicated in the operational sections of this specification is not implied. Ex-  
posure to absolute maximum rating conditions for extended periods may affect device reliability.  
11.2  
General Operating Conditions  
Symbol  
Parameter Description  
Min  
Typ  
Max  
Units  
V
Supply voltage  
Case temperature  
4.75  
0
5.25  
85  
V
C
CC  
T
C
11.3  
DC Characteristics  
11.3.1  
MII DC Characteristics  
Symbol  
Parameter Description  
Condition  
Min  
Typ  
Max  
Units  
V
Input low voltage (TTL)  
Input high voltage (TTL)  
Output low voltage  
0
0.8  
V
V
IL  
V
V
V
I
2.0  
IH  
I
I
= 4 mA  
0.45  
V
OL  
OH  
out  
out  
Output high voltage  
Input low leakage current  
Input capacitance  
= -4 mA  
2.4  
V
0 < V < V  
CC  
±15  
10  
µA  
pF  
IL  
in  
a
C
IN  
a. This parameter is only characterized, not tested. It is valid for digital pins only.  
11.3.2  
10BASE-T Voltage/Current DC Characteristics  
Symbol  
Parameter Description  
Condition  
DC and V  
Min  
Typ  
Max  
Units  
=
a
RDP  
R
Input differential resistance  
10  
KΩ  
ID10  
(V /2) + 0.5 V  
CC  
Datasheet  
43  
 
82555 — Networking Silicon  
Symbol  
Parameter Description  
Condition  
Min  
Typ  
Max  
Units  
5 MHz ≤ f ≤ 10 MHz  
5 MHz ≤ f ≤ 10 MHz  
V
V
V
Input differential accept voltage  
Input differential reject voltage  
Input common mode voltage  
±585  
±3100  
±300  
mV  
mV  
V
IDA10  
IDR10  
ICM10  
P
P
V
/2  
CC  
RL = 100 Ωb  
RBIAS10 = 768 Ω  
V
I
Output differential voltage  
Line driver supply  
±2.2  
±2.8  
V
OD10  
c
RBIAS10 = 768 Ω  
110  
120  
230  
mA  
mA  
mA  
mA  
CCT10  
d
I
I
Current on all V pins  
CC10  
CC  
Total supply current  
CCT10TOT  
e
L
Leakage on analog pins  
20  
ILA10  
a. This value is measured across the receive differential pins, RDP and RDN.  
b. RL is the resistive load across the receive differential pins, RDP and RDN.  
c. Transmitter current is measured with a 1:1 transformer on the center tap.  
d. Current is measured on all VCC pins at VCC = 5.25 V.  
e. The analog pins are: TDP, TDN, RDP, RDN, RBIAS10, and RBIAS100.  
Rbias10  
805Ω  
768Ω  
735Ω  
Icct10  
1 1 5 m A  
1 0 5 m A  
1 1 0 m A  
Figure 11. RBIAS10 Resistance versus ICCT10  
11.3.3  
100BASE-TX Voltage/Current DC Characteristics  
Symbol  
Parameter Description  
Condition  
Min  
Typ  
Max  
Units  
DC  
V
0.5 V  
= (V /2) +  
CC  
RDP  
R
Input differential resistance  
10  
KΩ  
ID100  
V
= (V /2) -  
CC  
RDN  
0.5 V  
V
V
V
V
Input differential accept voltage  
Input differential reject voltage  
Input common mode voltage  
Output differential voltage  
Line driver supply  
±500  
±100  
mV  
mV  
V
IDA100  
IDR100  
ICM100  
P
P
V
/2  
CC  
a
RBIAS100 = 634 Ω  
RBIAS100 = 634 Ω  
±0.95  
±1.00  
±1.05  
V
P
OD100  
b
I
40  
mA  
CCT100  
44  
Datasheet  
 
Networking Silicon — 82555  
Symbol  
Parameter Description  
Current on all V pins  
Condition  
Min  
Typ  
Max  
Units  
c
I
235  
275  
mA  
mA  
CC100  
CC  
ICCT100TOT Total supply current  
a. Transmitter current is measured with a 1:1 transformer on the center tap.  
b. Transmitter current is measured with a 1:1 transformer on the center tap.  
c. Current is measured on all VCC pins at VCC = 5.25 V.  
Rbias100  
667Ω  
634Ω  
604Ω  
Icct100  
4 2 m A  
3 8 m A  
4 0 m A  
Figure 12. RBIAS100 Resistance versus ICCT100  
11.4  
AC Characteristics  
Output Levels  
Input Levels  
V
V
= 2.4 V  
V
V
= 2.0 V  
= 0.8 V  
OH  
IH  
= 0.45 V  
OL  
IL  
Figure 13. AC Testing Level Conditions  
11.4.1  
MII Clock Specifications  
Symbol  
Parameter  
Conditions  
Min  
Typ  
Max  
Units  
T1  
T2  
T3  
T4  
T5  
T6  
T
TXC/RXC period  
TXC/RXC period  
MDC clock period  
TXC duty cycle  
RXC duty cycle  
MDC duty cycle  
100 Mbps  
10 Mbps  
40  
ns  
ns  
ns  
%
%
%
P100  
P10  
T
T
T
T
T
400  
400  
35  
PMDC  
TXDC  
RXDC  
MDC  
65  
65  
65  
35  
35  
Datasheet  
45  
 
82555 — Networking Silicon  
1.5V  
T4,T5,T6  
T4,T5,T6  
T1,T2,T3  
Figure 14. MII Clocks AC Timing  
11.4.2  
MII Timing Parameters  
Symbol  
Parameter  
Conditions  
Min  
Typ  
Max  
Units  
TXD[3:0], TXEN, TXERR setup  
from the rising edge of TXC  
T7  
T
15  
25  
ns  
TXDV  
TXH  
RXSU  
RXH  
MSU  
MH  
TXD[3:0], TXEN, TXERR hold  
time after the rising edge of TXC  
T8  
T
T
T
T
T
T
0
10  
10  
10  
10  
300  
ns  
ns  
ns  
ns  
ns  
ns  
RXD[3:0], RXDV, RXERR valid  
before the rising edge of RXC  
T9  
RXD[3:0], RXDV, RXERR hold  
time after the rising edge of RXC  
T10  
T11  
T12  
T13  
MDIO setup time to the rising  
edge of MDC  
MDIO input  
MDIO input  
MDIO output  
MDIO hold time from the rising  
edge of MDC  
MDIO valid from the rising edge  
of MDC  
MV  
TXCLK  
T8  
TXD[3:0],  
Data Invalid  
Data Valid  
Data Invalid  
TXER,TXEN  
T7  
Figure 15. MII Transmit Timing Parameters  
46  
Datasheet  
 
Networking Silicon — 82555  
RXCLK  
T9  
T10  
RXD[3:0],  
RXER,RXDV  
Data Invalid  
Data Valid  
Data Invalid  
Figure 16. MII Receive Timing Parameters  
MDC  
T11  
T12  
Data Invalid  
Data Valid  
Data Invalid  
Data Invalid  
MDIO (Input)  
T13  
Data Invalid  
Data Valid  
MDIO (Output)  
Figure 17. MII Timing Parameters: MDC/MDIO  
11.4.3  
Repeater Mode Timing Parameters  
Symbol  
Parameter  
Conditions  
Min  
Typ  
Max  
Units  
PORTEN assertion to RXD[3:0],  
RXDV, and RXERR (RXC driven)  
RXC  
clocks  
T14  
T15  
T
1.5  
2.5  
RDRV  
RTST  
PORTEN de-assertion to  
RXD[3:0], RXDV, and RXERR  
(RXC tri-stated)a  
RXC  
clocks  
T
1.5  
2.5  
a. RXC, RXDV, and RXERR are tri-stated only after they have been driven low (0).  
PORTEN  
T14  
T15  
RXD[3:0],  
RXER,RXDV,  
RXCLK  
Signal Driven  
Figure 18. PORT Enable Timing  
Datasheet  
47  
 
82555 — Networking Silicon  
11.4.4  
Transmit Packet Timing Parameters  
Symbol  
Parameter  
Conditions  
Min  
Typ  
Max  
Units  
TXC on first TXEN active to start  
of frame  
T15  
T
100 Mbps  
10  
12  
bits  
XEN_ST  
XEN_ST  
TXC on first TXEN active to start  
of frame  
T15a  
T
10 Mbps  
100 Mbps  
10 Mbps  
100 Mbps  
10 Mbps  
100 Mbps  
3.5  
5
4
bits  
bits  
bits  
bits  
bits  
bits  
TXC on first TXEN active to  
rising edge of CRS  
T16 TXEN_CRSH  
TXC on first TXEN active to  
rising edge of CRS  
T16a  
T17  
TXEN_CRSH  
1.5  
17  
5
TXC on first TXEN inactive to  
end of frame  
T
T
XEN_END  
XEN_END  
TXC on first TXEN inactive to  
end of frame  
T17a  
TXC on first TXEN inactive to  
falling edge of CRS  
T18 TXEN_CRSL  
11  
TXC on first TXEN inactive to  
falling edge of CRS  
T18a  
T19  
TXEN_CRSL  
10 Mbps  
10 Mbps  
6
bits  
ns  
T
End of frame high time  
250  
350  
EOF  
TXCLK  
TXEN  
CRS  
T16,T16a  
T18,T18a  
T17,T17a  
T15,T15a  
Frame On link  
Valid Frame Data  
Figure 19. Transmit Frame Timing Parameters  
11.4.5  
Squelch Test Timing Parameters  
Symbol  
Parameter  
Conditions  
Min  
Typ  
Max  
Units  
T20  
T21  
T
Collision detect heartbeat delay  
10 Mbps  
7
8
bits  
SQE_DEL  
SQE_DUR  
Collision detect heartbeat  
duration  
T
10 Mbps  
9
11  
bits  
48  
Datasheet  
 
Networking Silicon — 82555  
TXCLK  
TXEN  
COL  
T20  
T21  
Figure 20. Squelch Test Timing Parameters  
11.4.6  
Jabber Timing Parameters  
Symbol  
Parameter  
Conditions  
Min  
Typ  
Max  
Units  
Jabber turn-on delay (TXEN  
asserted to end of transmit  
frame)  
T22  
T23  
T
10 Mbps  
26  
ms  
JAB_ON  
Jabber turn-off delay (TXEN de-  
asserted to falling edge of COL)  
T
10 Mbps  
410  
ms  
JAB_OFF  
TXEN  
COL  
T23  
T22  
TDP/TDN  
Figure 21. Jabber Timing Parameters  
11.4.7  
Receive Packet Timing Parameters  
Symbol  
Parameter  
Conditions  
Min  
Typ  
Max  
Units  
Start of receive frame to rising  
edge of CRS  
T24  
T
100 Mbps  
11  
13  
bits  
R_CRSH  
R_CRSH  
Start of receive frame to rising  
edge of CRS  
T24a  
T
10 Mbps  
100 Mbps  
10 Mbps  
100 Mbps  
3
5
bits  
bits  
bits  
bits  
Start of receive frame to rising  
edge of RXDV  
T25 TR_RXDVH  
15  
22  
16  
Start of receive frame to rising  
edge of RXDV  
T25a  
T26  
TR_RXDVH  
End of receive frame to falling  
edge of CRS  
T
14  
R_CRSL  
Datasheet  
49  
 
82555 — Networking Silicon  
Symbol  
Parameter  
Conditions  
Min  
Typ  
Max  
Units  
End of receive frame to falling  
edge of CRS  
T26a  
T
10 Mbps  
4.5  
bits  
R_CRSL  
End of receive frame to falling  
edge of RXDV  
T27 TR_RXDVL  
TR_RXDVL  
100 Mbps  
10 Mbps  
12  
4
bits  
bits  
End of receive frame to falling  
edge of RXDV  
T27a  
RXCLK  
RXDV  
T25,T25a  
T24,T24a  
CRS  
T27,T27a  
T26,T26a  
Frame On link  
Valid Frame Data  
Figure 22. Receive Packet Timing Parameters  
11.4.8  
10BASE-T Normal Link Pulse (NLP) Timing Parameters  
Symbol  
Parameter  
Conditions  
Min  
Typ  
Max  
Units  
T28  
T29  
T
NLP width  
10 Mbps  
10 Mbps  
100  
ns  
NLP_WID  
NLP_PER  
T
NLP period  
8
24  
ms  
T29  
T28  
Normal Link Pulse  
Figure 23. Normal Link Pulse Timing Parameters  
11.4.9  
Auto-Negotiation Fast Link Pulse (FLP) Timing Parameters  
Symbol  
Parameter  
Conditions  
Min  
Typ  
Max  
Units  
T30  
T
FLP width (clock/data)  
100  
125  
62.5  
ns  
µs  
µs  
FLP_WID  
T31 TFLP_CLK_CLK  
T32 TFLP_CLK_DAT  
Clock pulse to clock pulse period  
Clock pulse to data pulse period  
111  
139  
55.5  
69.5  
50  
Datasheet  
 
Networking Silicon — 82555  
Symbol  
Parameter  
Conditions  
Min  
Typ  
Max  
Units  
T33 TFLP_BUR_NUM Number of pulses in one burst  
T34 TFLP_BUR_WID FLP Burst width  
17  
33  
2
ms  
ms  
T35 TFLP_BUR_PER FLP burst period  
8
24  
T30  
T31  
T30  
Fast Link Pulse  
Clock Pulse  
Data Pulse  
Clock Pulse  
T35  
T34  
FLP Bursts  
Figure 24. Fast Link Pulse Timing Parameters  
11.4.10  
Reset Timing Parameters  
Symbol  
Parameter  
Reset pulse width  
Conditions  
Min  
Typ  
Max  
Units  
T36  
T37  
T
500  
500  
ns  
RST_WID  
PUP_RST  
T
Power-up to falling edge of reset  
µs  
Power Up (VCC)  
T37  
T36  
RESET  
Figure 25. Reset Timing Parameters  
11.4.11  
X1 Clock Specifications  
Symbol  
Parameter  
Conditions  
Min  
Typ  
Max  
Units  
T38  
T39  
T
X1 duty cycle  
X1 period  
40  
60  
%
X1_DC  
X1_PR  
T
±50 PPM  
40  
ns  
Datasheet  
51  
 
82555 — Networking Silicon  
4.0V  
2.5V  
0.4V  
T39  
T39  
T38  
Figure 26. X1 Clock Specifications  
11.4.12  
100BASE-TX Transmitter AC Specification  
Symbol  
Parameter  
Conditions  
Min  
Typ  
Max  
Units  
TDP/TDN differential output peak  
jitter  
T40  
T
HLS data  
300  
700  
ps  
JIT  
52  
Datasheet  
 
Networking Silicon — 82555  
12.0  
82555 Package Information  
This section provides the physical packaging information for the 82555. The 82555 is an 100-pin  
plastic Quad Flat Pack (QFP) device. Package attributes are provided in Table 7 and the dimensions  
are shown in Figure 27.  
D
D1  
A1  
E
E1  
A
e
b
C
De ta il A  
Se a ting  
Pla ne  
Y
Se e De ta il A  
T
L1  
PC-3712  
Figure 27. Dimension Diagram for the 82555 QFP  
Table 7. Dimensions for the 82555 QFP  
Symbol  
Description  
Min  
Norm  
100  
Max  
N
A
Lead Count  
Overall Height  
Stand Off  
-
-
-
-
3.15  
0.40  
0.40  
0.20  
18.3  
-
A1  
b
0.05  
0.20  
0.10  
17.5  
-
-
Lead Width  
0.30  
0.15  
17.9  
14.0  
23.9  
20.0  
0.65  
0.80  
c
Lead Thickness  
Terminal Dimension  
Package Body  
Terminal Dimension  
Package Body  
Lead Pitch  
D
D1  
E
23.5  
-
24.3  
-
E1  
e1  
L1  
0.53  
0.60  
0.77  
1.00  
Foot Length  
Datasheet  
53  
 
   
82555 — Networking Silicon  
Table 7. Dimensions for the 82555 QFP  
Symbol  
Description  
Min  
Norm  
Max  
T
Y
Lead Angle  
Coplanarity  
0.0  
-
-
-
10.0  
0.10  
54  
Datasheet  
 

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