dm9301fp Davicom Semiconductor, Inc., dm9301fp Datasheet - Page 12

• Manufacturer Part Number: dm9301fp
• Description: 100mbps Ethernet Fiber/twisted Pair Single Chip Media Converter
• Manufacturer: Davicom Semiconductor, Inc.

100Base-TX to FX Operation
The block diagram in figure 2 provides an overview of the
functional blocks contained in the TX to FX media
converter interface.
The TX to FX interface contains the following functional
blocks:
•
•
•
•
•
•
•
•
•
•
TX Signal Detect
The signal detects function meets the specifications
mandated by the ANSI XT12 TP-PMD100Base-TX
standards for both voltage thresholds and timing
parameters.
12
TX Digital Adaptive Equalization
TX MLT-3 to NRZI
TX Clock Recovery Module
TX NRZI to NRZ Decoder
TX Serial to Parallel Conversion
TX Descrambler
TX Code Group Alignment Monitor
FX Parallel to Serial Conversion
FX NRZ to NRZI
FX PECL Transmitter
PECLTXO +/-
OSC/XTAL
25M
TXMT
PECL
TX
CGM
NRZI
NRZ
TX
to
to Serial
Parallel
FX
100Mbps Ethernet Fiber/Twisted Pair Single Chip Media Converter
Alignment
TX Code-
Monitor
group
TX to FX Block Diagram
TX Link
Monitor
Status
Descrambler
TX
25M TPRXCLK
Figure 2
Serial to
Parallel
TX
TX Digital Adaptive Equalization
When transmitting data at high speeds over copper
twisted pair cable, attenuation based on frequency
becomes a concern. In high speed twisted pair signaling,
the frequency content of the transmitted signal can vary
greatly during normal operation based on the randomness
of the scrambled data stream. This variation in signal
attenuation caused by frequency variations must be
compensated for to ensure the integrity of the received
data. In order to ensure quality transmission when
employing MLT-3 encoding, the compensation must be
Able to adapt to various cable lengths and cable types
depending on the installed environment. The selection of
long cable lengths for a given implementation requires
significant compensation which will be over-kill in a
situation that includes shorter, less attenuating cable
lengths. Conversely, the selection of short or intermediate
cable lengths requiring less compensation will cause
serious under-compensation for longer length cables.
125M TPRXCLK
NRZI
NRZ
TX
to
CRM
TX
MLT-3 to
NRZI
TX
Adaptive
EQ
TX
DM9301FP
Version: DM9301FP-DS-F03
TPRXI+/-
June 06, 2007
Final