1 Features
1• 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 ±7 V
• ±0.2 V Receiver Sensitivity Over the Input Voltage
Range
• Receiver Input Hysteresis: 70 mV Typical
• DS8921AT Industrial Temperature Operation:
(−40°C to +85°C)

2 Applications
• Differential Line Driver and Receiver for:
– ST506 Disk Drive Standard
– ST412 Disk Drive Standard
– ESDI Disk Drive Standard
– RS-422 Interface

3 Description
The DS8921, DS8921A, and DS8921AT devices are
differential line driver and receiver pairs designed specifically for applications meeting the ST506,
ST412, and ESDI disk drive standards. In addition,
these devices meet the requirements of the EIA
standard RS-422.
The DS8921x receivers offer an input sensitivity of
200 mV over a ±7 V common mode operating range.
Hysteresis is incorporated (typically 70 mV) to
improve noise margin for slowly changing input
waveforms.
The DS8921x drivers are designed to provide
unipolar differential drive to twisted-pair or parallel
wire transmission lines. Complementary outputs are
logically ANDed and provide an output skew of 0.5 ns
(typical) with propagation delays of 12 ns.
The DS8921x devices are designed to be compatible
with TTL and CMOS.