DS8922/DS8922A/DS8923A TRI-STATE RS-422 Dual Differential Line Driver and Receiver Pairs
July 2004
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
assumes 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
00851101
Order Number DS8922M, DS8922N,
DS8922AM or DS8922AN
See NS Package Number M16A or N16E
TRI-STATE
®
is a registered trademark of National Semiconductor Corp.
© 2004 National Semiconductor Corporation
DS008511
www.national.com
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