COM20020_00 Datasheet, PDF (23/82 Pages) SMSC Corporation – Universal Local Area Network Controller with 2K x 8 On-Board RAM

When the device is in Backplane Mode, the clock
provided by the nPULSE2 signal may be used for
encoding the data into a different encoding
scheme or other synchronous operations needed
on the serial data stream.
Differential Driver Configuration
The Differential Driver Configuration is a special
case of the Backplane Mode. It is a dc coupled
configuration recommended for applications like
car-area networks or other cost-sensitive
applications which do not require direct
compatibility with existing ARCNET nodes and do
not require isolation.
The Differential Driver Configuration cannot
communicate directly with nodes utilizing the
Traditional Hybrid Configuration. Like the
Backplane Configuration, the Differential Driver
Configuration does not isolate the node from the
media.
The Differential Driver interface includes a RS485
Driver/Receiver to transfer the data between the
cable and the COM20020. The nPULSE1 signal
transmits the data, provided the Transmit Enable
signal is active. The nPULSE1 signal issues a
200nS (at 2.5Mbps) negative pulse to transmit a
logic "1". Lack of pulse indicates a logic "0". The
RXIN signal receives the data, the transmitter
portion of the COM20020 is disabled during reset
and the nPULSE1, nPULSE2 and nTXEN pins are
inactive.
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