LAN91C94 datasheet(86/120 Pages) SMSC

86 / 120 page

Reverse Polarity Function

In the 10BASE-T mode, the PHY monitors for

receiver polarity reversal due to crossed wires

and corrects by reversing the signal internally.

Collision Detection Function

In the 10BASE-T mode, a collision state is

indicated

when

there

are

simultaneous

transmissions and receptions on the twisted pair

link. During a collision state, the nCOLL signal

is asserted. If the received data ends and the

transmit control signal is still active, the transmit

data is sent to the MAC within 9 bit times. The

nCOLL signal is de-asserted within 9 bit times

after

the

collision

terminates.

the AUI mode, the external transceiver sends a

10MHz signal to the PHY upon detection of a

collision.

Link Integrity

The PHY test for a faulty twisted-pair link. In the

absence of transmit data, link test pulses are

transmitted every 16+/-18ms after the end of the

last transmission or link pulse on the twisted

pair medium. If neither valid data nor link test

pulses are received within 10 to 150ms, the link

is declared bad and both data transmission as

well as the operational loopback function are

disabled.

The Link Integrity function can be

disabled

for

pre-10BASE-T

twisted-pair

networks.

LAN91C94 Datasheet(PDF) 86 Page - SMSC Corporation