DS3662

General Description

The DS3662 is a quad high speed Schottky bus transceiver

intended for use with terminated 120

Ω 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 15 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

Ω resistor

from the bus to 5V logic supply, together with a 390

Ω resistor

from the bus to ground. The bus can be terminated at one or

both ends. A two input NOR gate is provided to disable all

drivers in a package simultaneously.

Features

n Pin to pin functional replacement for DS8641

n Guaranteed AC specifications on noise immunity and

propagation delay over the specified temperature and

supply voltage range

n Temperature insensitive receiver thresholds track bus

logic level

n Trapezoidal bus waveforms reduce noise coupling to

adjacent lines

n Precision receiver thresholds provide maximum noise

immunity and symmetrical response to positive and

negative going pulses

n Open collector driver output allows wire-OR connection

n High speed Schottky technology

with V

n Glitch free power up/down protection on the driver

output

n TTL compatible driver and disable inputs, and receiver

outputs

Block and Connection Diagram

Dual-In-Line Package

DS005803-1

Top View

Order Number DS3662J, DS3662N or DS3662WM

See NS Package Number J16A, N16A or M16B

July 1992

© 1999 National Semiconductor Corporation

DS005803

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