DS8922/DS8922A/DS8923A TRI-STATE RS-422 Dual Differential Line Driver and Receiver Pairs
June 1998
DS8922/DS8922A/DS8923A TRI-STATE
®
RS-422 Dual Differential Line Driver and Receiver Pairs
General Description
The DS8922/22A and DS8923A are Dual Differential Line
Driver and Receiver pairs. These devices are designed spe-
cifically for applications meeting the ST506, ST412 and
ESDI Disk Drive Standards. In addition, the devices meet the
requirements of the EIA Standard RS-422.
These devices offer an input sensitivity of 200 mV over a
±
7V common mode operating range. Hysteresis is incorpo-
rated (typically 70 mV) to improve noise margin for slowly
changing input waveforms. An input fail-safe circuit is pro-
vided such that if the receiver inputs are open the output as-
sumes the logical one state.
The DS8922A and DS8923A drivers are designed to provide
unipolar differential drive to twisted pair or parallel wire trans-
mission lines. Complementary outputs are logically ANDed
and provide an output skew of 0.5 ns (typ.) with propagation
delays of 12 ns.
Both devices feature TRI-STATE outputs. The DS8922/22A
have independent control functions common to a driver and
receiver pair. The DS8923A has separate driver and receiver
control functions.
Power up/down circuitry is featured which will TRI-STATE
the outputs and prevent erroneous glitches on the transmis-
sion lines during system power up or power down operation.
The DS8922/22A and DS8923A are designed to be compat-
ible with TTL and CMOS.
Features
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12 ns typical propagation delay
Output skew —
±
0.5 ns typical
Meets the requirements of EIA Standard RS-422
Complementary Driver Outputs
High differential or common-mode input voltage ranges
of
±
7V
±
0.2V receiver sensitivity over the input voltage range
Receiver input fail-safe circuitry
Receiver input hysteresis — 70 mV typical
Glitch free power up/down
TRI-STATE outputs
Connection Diagrams
DS8922A Dual-In-Line
DS008511-1
Order Number DS8922M, DS8922N,
DS8922AM or DS8922AN
See NS Package Number M16A or N16E
TRI-STATE
®
is a registered trademark of National Semiconductor Corp.
© 1998 National Semiconductor Corporation
DS008511
www.national.com
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