74740-0001 Datasheet, PDF (2/11 Pages) Molex Electronics Ltd. – 1000Base-T RJ-45 Gigabit Ethernet GBIC Copper Transceiver

1000BASE-T RJ-45 GBIC FEATURES
1000Base-T RJ-45 Gigabit
Ethernet GBIC Copper
Transceiver
GBIC Mode
When the internal gigabit Ethernet transceiver (PHY) is configured to GBIC mode, the PHY can interface directly with the host serial/deserial
(SERDES) interface. The host interface transmits and receives serial data differentially at 1.25Gbps. The copper interface is full featured
and advertises full/half duplex, and 1000Base-T wire speed.
Auto-Negotiation
Auto-Negotiation is supported over both the twisted pair copper link and SERDES interface as defined in the IEEE 802.3 standards and is
performed as part of the initial set-up of the link. The copper link is negotiated according to the IEEE 802.3 Clause 28, and Clause 37 is
used in the negotiation of the SERDES interface. The two interfaces advertise 1000Base-T full-duplex, and master/slave relationships. The
master establishes the time control from its local clock source. The slave however recovers the clock from the received data stream. The
GBIC application is limited to 1000Base-T wire speed only. Auto-Negotiation on the SERDES link is always restarted when a change is
detected on copper link (see Link Monitor and Loss-of-Signal for further details).
Automatic MDI Crossover
The 1000Base-T GBIC transceiver performs a MDI crossover during Auto-Negotiation eliminating the need for crossover cables or cross-
wired (MDIX) ports.
Loss of Signal - Link Monitor
Following Auto-Negotiation, the master and slave begin sending data over the twisted pair link. The master and slave continuously monitor
the copper link for quality of data. The link status bit is set after one microsecond of quality data. If the quality of copper link drops below
factory PHY minimums, the GBIC will drop the SERDES link, and assert the LOS I/O interface (optional) in less than 200 milliseconds.
Auto Power Savings Mode
When the copper link is lost, the GBIC automatically enters a low power mode reducing the chip power requirements. Full power mode
resumes once the copper link is re-established.
Not Implemented in GBIC Auto-Negotiation
Next page exchange and detection of remote faults are not auto-negotiated.