M74HCT651

M74HCT652

October 1993

HCT652 OCTAL BUS TRANSCEIVER/REGISTER (3-STATE)

HCT651 OCTAL BUS TRANSCEIVER/REGISTER (3-STATE, INV.)

INPUT AND OUTPUT EQUIVALENT CIRCUIT

.

HIGH SPEED

.

COMPATIBLE WITH TTL OUTPUTS

.

LOW POWER DISSIPATION

.

OUTPUT DRIVE CAPABILITY

15 LSTTL LOADS

.

SYMMETRICAL OUTPUT IMPEDANCE

.

BALANCED PROPAGATION DELAYS

.

PIN AND FUNCTION COMPATIBLE

WITH 54/74LS651/652

DESCRIPTION

M74HCT651/652 are high speed CMOS OCTAL

BUS

TRANSCEIVERS

AND

REGISTERS

(3-STATE), fabricated in silicon gate C

technology. They have the same high speed

performance of LSTTL combined with true CMOS

low power consumption. These devices consist of

bus transceiver circuits, D-type flip-flops, and control

circuitry arranged for multiplexed transmission of

data directly from the input bus or from the internal

storage registers. Enable GAB and GBA are

provided to control the transceiver functions. Select

AB and Select BA control pins are provided to select

whether real-time or stored data is transfered. A low

input level selects real-time data, and a high selects

stored data. Data on the A or B bus, or both, can be

stored in the internal D flip-flops by low-to-high

transitions at the appropriate clock pins (CLOCK AB

or CLOCK BA) regardless of the select or enable

control pins. When select AB and select BA are in the

real-time transfer mode, it is also possible to store

data without using the internal D-type flip-flops by

simultaneously enabling GAB and GBA. In this

configuration each output reinforces its input. Thus,

when all other data sources to the two sets of bus

lines are at high impedance, each set of bus lines will

remain at its last state. All inputs are equipped with

protection circuits against static discharge and

transient excess voltage.This integrated circuit has

input and output characteristics that are fully

compatible

with 54/74

LSTTL

logic

families.

M54/74HCT devices are designed to directly

interface HSCMOS systems with TTL and NMOS

components. They are also plug in replacements for

LSTTL devices giving a reduction of power

consumption.

GAB, GAB, CAB,

A, B

SAB, SBA, CBA

B1R

(Plastic Package)

ORDER CODES :

M74HCXXXM1R

M74HCXXXB1R

M1R

(Micro Package)

PIN CONNECTIONS (top view)

1/12