DS3862 Octal High Speed Trapezoidal Bus Transceiver
February 1995
DS3862
Octal High Speed Trapezoidal Bus Transceiver
General Description
The DS3862 is an octal high speed schottky bus transceiver
intended for use with terminated 120鈩?impedance lines. It is
specifically designed to reduce noise in unbalanced trans-
mission systems. The open collector drivers generate pre-
cise trapezoidal waveforms with rise and fall times of 9 ns
(typical), which are relatively independent of capacitive load-
ing conditions on the outputs. This reduces noise coupling to
the adjacent lines without any appreciable impact on the
maximum data rate obtainable with high speed bus trans-
ceivers. In addition, the receivers use a low pass filter in con-
junction with a high speed comparator, to further enhance
the noise immunity. Tightly controlled threshold levels on the
receiver provide equal rejection to both negative and positive
going noise pulses on the bus.
The external termination is intended to be a 180鈩?resistor
from the bus to 5V logic supply, together with a 390鈩?resistor
from the bus to ground. The bus can be terminated at one or
both ends.
Features
n
Guaranteed A.C. specifications on noise immunity and
propagation delay over the specified temperature and
supply voltage range
n
Temperature insensitive receiver thresholds track bus
logic level and respond symmetrically to positive and
negative going pulses
n
Trapezoidal bus waveforms reduce noise coupling to
adjacent lines
n
Open collector driver output allows wire-or connection
n
Advanced low power schottky technology
n
Glitch free power up/down protection on driver and
receiver outputs
n
TTL compatible driver and control inputs, and receiver
outputs
n
Control logic is the same as the DS3896
Logic and Connection Diagram
DS008539-1
Order Number DS3862J, DS3862N or DS3862WM
See NS Package Number J20A, N20A or M20B
漏 1999 National Semiconductor Corporation
DS008539
www.national.com
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