ML4658

3

PIN# NAME

FUNCTION

12 POLRD

Receive Polarity status. Active low LED Driver, open collector output. Indicates the polarity of the

receive twisted pair regardless of auto polarity correction. When this pin is high, the receive polarity

is correct, and when this pin is low the receive polarity is reversed.

13 XMT

Indicates that transmission is taking place on the TxTP+, TxTP– pair. Active low LED driver, open

collector. It is extended 100ms for visibility.

14 RCV

Indicates that the transceiver has unsquelched and is receiving data from the twisted pair. Active low

LED driver, open collector. It is extended 100ms for visibility.

15 TxTP–

Pre-equalized differential balanced current driven output. These ouputs are connected to a balanced

16 TxTP+

transmit output filter which drives the twisted pair cable through pulse transformers. The output current

is set with an external resistor connected to RTSET allowing the chip to drive 100

Ω unshielded twisted

pair, 150

Ω shielded twisted pair cables or a range of other characteristic impedances.

17 GND

Ground reference.

18 TxCAP1

An external capacitor of 330pF is tied between these two pins to set the pulse width for the pre-

19 TxCAP0

equalization on the transmitter. If these two pins are shorted together, no pre-equalization occurs.

20 LTF

Link Test Fail. Active high. Normally this pin is low, indicating that the link is operational. If the link

goes down resulting from the absence of link pulses or frames being received, the chip will go into

the Link Test Fail state and bring LTF high. In the Link Test Fail state, both the transmitter and receiver

are disabled, however link pulses are still sent. A station that only has access to the AUI can detect a

Link Test Fail by the absence of loopback. This pin is low when the Link Test is disabled. Open

collector LED output.

21 RxTP–

Twisted Pair receive data input. When this signal exceeds the receive squelch requirements the

receive

22 RxTP+

data is buffered and sent to the Rx± outputs.

23 BIAS

Bias voltage, output. Used to bias the receive twisted pair inputs as well as the Tx± inputs when they

are AC coupled.

24 JAB

Open collector TTL output capable of driving an LED. When in the Jabber state, this pin will be low

and the transmitter will be disabled. In the Jabber “OK” state this pin will be high.