TLK100_11 Datasheet, PDF (26/88 Pages) Texas Instruments – Industrial Temp, Single Port 10/100 Mb/s Ethernet Physical Layer Transceiver

TLK100
SLLS931B – AUGUST 2009 – REVISED DECEMBER 2009
www.ti.com
5 Architecture
The TLK100 Fast Ethernet transceiver is physical layer core for Ethernet 100Base-TX and 10Base-T
applications. It contains all the active circuitry required to implement the physical layer functions to
transmit and receive data on standard CAT 3 and 5 unshielded twisted pair. The core supports the IEEE
802.3 Standard Fast Media Independent Interface (MII) for direct connection to a MAC/Switch port.
The TLK100 uses mixed signal processing to perform equalization, data recovery and error correction to
achieve robust and low power operation over the existing CAT 5 twisted pair wiring. The TLK100
architecture not only meets the requirements of IEEE802.3, but maintains a high level of margin over the
IEEE requirements for NEXT and Alien noise.
4B/5B
encoding
Manchester
encoding
Scrambler
NRZ to NRZI
Convertor
MLT-3
encoding
Transmit
D/A
Convertor
100Base TX
Line Driver
10Base T
Filter
10Base T
Line Driver
MII
Adv.
Link Monitor
100Base TX
10Base-T
Manchester
decoding
Receive
4B/5B
decoding
DeScrambler
NRZI to NRZ
Convertor
MLT-3
decoding
DSP (BLW
Correction,
Adapt. Equal)
10Base T
Receive
Filter
ADC (Filter,
Amplifierl)
Figure 5-1. PHY Architecture
5.1 Transmit Path Encoder
In 10Base-T, the MAC feeds the 10Mbps transmit data through the MII in 4-bit wide nibbles. The data is
serialized using an NRZI converter; Manchester encoded and sent to DAC to be transmitted through one
of the twisted pairs of the cable. When no data is available from the MAC, the 10B-T encoder transmits
NLP pulses to keep the link alive.
In 100Base-TX, the MAC feeds the 100Mbps transmit data in 4-bit wide nibbles through the MII interface.
The data is encoded into 5-bit code groups, encapsulated with control code symbols and serialized. The
control-code symbols indicate the start and end of the frame and code other information such as transmit
errors. When no data is available from the MAC, IDLE symbols are constantly transmitted. The serialized
bit stream is fed into a scrambler. The scrambled data stream passes through an NRZI encoder and then
through an MLT3 encoder. Finally, it is fed to the DAC and transmitted through one of the twisted pairs of
the cable.
5.1.1 4B/5B Encoding
The transmit data that is received from the MAC first passes through the 4B/5B encoder. This block
encodes 4-bit nibble into 5-bit code-groups according to the Table 5-1. Each 4-bit data nibble is mapped to
16 of the 32 possible code-groups. The remaining 16 code-groups are either used for control information
or they are considered as not valid.
The code-group encoder substitutes the first 8-bits of the MAC preamble with a J/K code-group pair
(11000 10001) upon transmission. The code-group encoder continues to replace subsequent 4-bit
preamble and data nibbles with corresponding 5-bit code-groups. At the end of the transmit packet, upon
the de-assertion of Transmit Enable signal from the MAC, the code-group encoder adds the T/R
code-group pair (01101 00111) indicating the end of the frame.
26
Architecture
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