COM20022I datasheet(9/82 Pages) SMSC

9 / 82 page

10 Mbps ARCNET (ANSI 878.1) Controller with 2Kx8 On-Board RAM

Datasheet

SMSC COM20022I

Page 9

Revision 02-27-06

DATASHEET

PIN NO

NAME

SYMBOL

I/O

DESCRIPTION

TRANSMISSION MEDIA INTERFACE

nPulse 1

nPulse 2

nPULSE1

nPULSE2

OUT

I/O

In Normal Mode, these active low signals carry the transmit

data information, encoded in pulse format as DIPULSE

waveform. In Backplane Mode, the nPULSE1 signal driver

is programmable (push/pull or open-drain), while the

nPULSE2 signal provides a clock with frequency of doubled

data rate. nPULSE1 is connected to a weak internal pull-up

resistor on the open/drain driver in backplane mode.

Receive In

RXIN

This signal carries the receive data information from the line

transceiver.

nTransmit

Enable

nTXEN

OUT

Transmission Enable signal. Active polarity is

programmable through the nPULSE2 pin.

nPULSE2 floating before power-up;

nTXEN active low

nPULSE2 grounded before power-up;

nTXEN active high (this option is only available in Back

Plane mode)

Crystal

Oscillator

XTAL1

XTAL2

OUT

An external crystal should be connected to these pins.

Oscillation frequency range is from 10 MHz to 20 MHz. If

an external TTL clock is used instead, it must be connected

to XTAL1 with a 390ohm pull-up resistor, and XTAL2 should

be left floating.

8,20,

32,43

Power

Supply

VDD

PWR

+5 Volt power supply pins.

6,11,

18,23,

30,41

Ground

VSS

PWR

Ground pins.

19,27

N/C

Non-connection

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