STE100P_06 Datasheet, PDF (16/31 Pages) STMicroelectronics – 10/100 FAST ETHERNET 3.3V TRANSCEIVER

STE100P
Data conversion of Parallel to Serial, NRZ to NRZI, NRZI to MLT3: After scrambled, the transmission
data with 5B type in 25MHz will be converted to serial bit stream in 125MHz by the parallel to serial func-
tion. After serialized, the transmission serial bit stream will be further converted from NRZ to NRZI format.
This NRZI conversion function can be bypassed, if the bit 7 of PR19 register is cleared as 0. After NRZI
converted, the NRZI bit stream is passed through MLT3 encoder to generate the TP-PMD specified MLT3
code. With this MLT3 code, it lowers the frequency and reduces the energy of the transmission signal in
the UTP cable and also makes the system easily to meet the FCC specification of EMI.
Wave-Shaper and Media Signal Driver: In order to reduce the energy of the harmonic frequency of trans-
mission signals, the device provides the wave-shaper prior to the line driver to smooth but keep symmetric
the rising/falling edge of transmission signals. The wave-shaped signals include the 100Base-TX and
10Base-T both are passed to the same media signal driver. This design can simplify the external magnetic
connection with single one.
7.2 100Base-TX Receive Operation
Regarding the 100Base-TX receiving operation, the device provides the receiving functions of PMD, PMA,
and PCS for receiving incoming data signals through category 5 UTP cable and an isolation transformer
with turns ratio of 1: 1. It includes the adaptive equalizer and baseline wander, data conversions of MLT3
to NRZI, NRZI to NRZ and serial to parallel, the PLL for clock and data recovery, the de-scrambler, and
the decoder of 5B/4B.
Adaptive Equalizer and Baseline Wander: Since the high speed signals over the unshielded (or shield-
ed) twisted Pair cable will induce the amplitude attenuation and phase shifting. Furthermore, these effects
are depends on the signal frequency, cable type, cable length and the connectors of the cabling. So a re-
liable adaptive equalizer and baseline wander to compensate all the amplitude attenuation and phase shift-
ing are necessary. In the transceiver, it provides the robust circuits to perform these functions.
MLT3 to NRZI Decoder and PLL for Data Recovery: After receiving the proper MLT3 signals, the device
converts the MLT3 to NRZI code for further processing. After adaptive equalizer, baseline wander, and
MLT3 to NRZI decoder, the compensated signals with NRZI type in 125MHz are passed to the Phase Lock
Loop circuits to extract out the original data and synchronous clock.
Data Conversions of NRZI to NRZ and Serial to Parallel: After data is recovered, the signals will be
passed to the NRZI to NRZ converter to generate the 125 MHz serial bit stream. This serial bit stream will
be packed to parallel 5B type for further processing. The NRZI to NRZ conversion can be bypassed, if the
bit 7 of PR19 register is cleared as 0.
De-scrambling and Decoding of 5B/4B: The parallel 5B type data is passed to de-scrambler and 5B/4B
decoder to return their original MII nibble type data.
Carrier sensing: Carrier Sense(CRS) signal is asserted when the STE100P detects any 2 non-contiguous
zeros within any 10 bit boundary of the receiving bit stream. CRS is de-asserted when ESD code-group or
Idle code-group is detected. In half duplex mode, CRS is asserted during packet transmission or receive.
But in full duplex mode, CRS is asserted only during packet reception.
7.3 10Base-T Transmit Operation
This includes the parallel to serial converter, Manchester Encoder, Link test function, Jabber function and
the transmit wave-shaper and line driver described in the section of “Wave-Shaper and Media Signal Driv-
er” of “100BASE-T Transmission Operation”. It also provides Collision detection and SQE test for half du-
plex application.
7.4 10Base-T Receive Operation
This includes the carrier sense function, receiving filter, PLL for clock and data recovering, Manchester
decoder, and serial to parallel converter.
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