DM9301 View Datasheet(PDF) - Davicom Semiconductor, Inc.
Part Name
Description
Manufacturer
DM9301 Datasheet PDF : 22 Pages
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DM9301
100Mbps Ethernet Fiber/Twisted Pair Single Chip Media Converter
FX Serial to Parallel Converter
The Serial to Parallel converter receives a serial
data stream from the NRZI to NRZ converter, and
converts the data stream to parallel data to be
presented to the scrambler. The parallel data format
presented to the TX scrambler is 5B coded.
FX Code Group Alignment Monitor
The FX Code Group Alignment block receives non-
aligned 5B data from the FX Serial to Parallel
converter and monitors it for 5B code group
violations. FX Code Group Alignment occurs after
the J/K is detected, and subsequent data is
monitored on a fixed boundary. If a violation is
detected, the FX Code Group Alignment Monitor
block signals the error to the Link Status Monitor
block. In turn, the Link Status Monitor block flashes
the FX error LED (FXERRLED#).
TX Scrambler
The scrambler also receives data from the FX Serial
to Parallel converter. Data from the serial to parallel
conversion block is 5B symbol encoded. The
scrambler is required to control the radiated
emissions (EMI) by spreading the transmit energy
across the frequency spectrum at the media
connector and on the twisted pair cable in 100Base-
TX transmit operation.
By scrambling the data, the total energy presented
to the cable is randomly distributed over a wide
frequency range. Without the scrambler, energy
levels on the cable could peak beyond FCC
limitations at frequencies related to repeated 5B
sequences like continuous transmission of IDLE
symbols. The scrambler output is combined with the
NRZ 5B data from the FX Serial to Parallel
converter via an XOR logic function. The result is a
scrambled data stream with sufficient randomization
to decrease radiated emissions at critical
frequencies.
TX Parallel to Serial Converter
The TX Parallel to Serial converter receives parallel
5B scrambled data from the scrambler and
serializes it (converts it from a parallel to a serial
data stream). The serialized data stream is then
presented to the NRZ to NRZI converter block
TX NRZ to NRZI Converter
After the transmit data stream has been scrambled
and serialized, the data must be NRZI encoded for
compatibility with the TP-PMD standard for
100Base-TX transmission over Category-5
unshielded twisted pair cable.
TX MLT-3 Converter
The MLT-3 conversion is accomplished by
converting the data stream output from the NRZI
encoder into two binary data streams with
alternately phased logic one events.
TX MLT-3 Driver
The two binary data streams created at the MLT-3
converter are fed to the twisted pair output driver
which converts these streams to current sources
and alternately drives either side of the transmit
transformer primary winding resulting in a minimal
current MLT-3 signal.
Final
11
Version: DM9301-DS-F02
May 8, 2000
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