COM20022I-3V Datasheet, PDF (9/83 Pages) SMSC Corporation – 10 Mbps ARCNET (ANSI 878.1) Controller with 2Kx8 On-Board RAM

10 Mbps ARCNET (ANSI 878.1) Controller with 2Kx8 On-Board RAM
Datasheet
PIN NO
38
NAME
Terminal
Count
40
Refresh
Execution
24
nPulse 1
25
nPulse 2
28
Receive In
29
nTransmit
Enable
21
Crystal
22
Oscillator
8,20,
32,43
6,11,
18,23,
30,41
19,27
Power
Supply
Ground
N/C
SYMBOL I/O
DESCRIPTION
TC
IN Terminal Count signal. Active polarity is
programmable. Default is active high. When
BUSTMG is High, this signal is connected to the
internal pull-up resistor.
nREFEX
IN Refresh execution signal. Falling edge detection.
This signal is connected to the internal pull-up
resistor.
TRANSMISSION MEDIA INTERFACE
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.
RXIN
IN This signal carries the receive data information from
the line transceiver.
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)
XTAL1
XTAL2
IN
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.
VDD
PWR +5 Volt power supply pins.
VSS
PWR Ground pins.
N/C
Non-connection
SMSC COM20022I 3V
Page 9
DATASHEET
Revision 02-27-06