DM9331A
100 Mbps Twisted Pair/Fiber Ethernet Media Converter Chip
1. General Description
The DM9331A is a physical-layer, single-chip, low
power transceiver for media converter application. On
the media side, it provides a direct interface either to
Unshielded Twisted Pair Category 5 Cable (UTP5) for
100BASE-TX Fast Ethernet, and it also provides
PECL interface to connect the external fiber optical
transceiver. Through the Media Converter Interface
(MCI), the DM9331A connects to another DM9331A
for the twisted pair to the fiber media converter, or
fiber to fiber repeater.
The DM9331A uses a low-power and high-
performance CMOS process. It contains the entire
physical layer functions of 100BASE-TX as defined by
IEEE802.3u, including the Physical Coding Sublayer
(PCS), Physical Medium Attachment (PMA), Twisted
Pair Physical Medium Dependent Sublayer (TP-PMD)
and a PECL compliant interface for a fiber optical
module, compliant with ANSI X3.166. The DM9331A
provides a strong support for the auto-negotiation
function, utilizing automatic selection of full or half-
duplex mode. Furthermore, due to the built-in wave-
shaping filter, the DM9331A needs no external filter to
transport signals to the media on the 100base-TX
Ethernet operation.
2. Block Diagram
100Base-FX
PECL
Interface
100Base-TX
Transceiver
100Base-
TX
PCS
Media
Converter
Interface
Auto-Negotiation
TX/RX Module
LED Driver
Clock
Circuit
Block
Biasing/
Power
Block
MII
Register
MII
Management
Control
Preliminary
1
Version: DM9331A-DS-P01
April 28, 2002