74HC646D,653 查看數據表（PDF） - NXP Semiconductors.

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74HC646D,653

Octal bus transceiver/register; 3-state

NXP Semiconductors. 

Philips Semiconductors

Octal bus transceiver/register; 3-state

Product specification

74HC/HCT646

Fig.4 Functional diagram.

FUNCTION TABLE

OE

H

H

L

L

L

L

DIR

X

X

L

L

H

H

INPUTS (1)

CPAB

H or L

↑

X

X

X

H or L

CPBA

H or L

↑

X

H or L

X

X

SAB

X

X

X

X

L

H

SBA

X

X

L

H

X

X

DATA I/O (2)

A0 to A7 B0 to B7

input

input

output

input

input

output

FUNCTION

isolation

store A and B data

real-time B data to A bus

stored B data to A bus

real-time A data to B bus

stored A data to B bus

Notes

1. H = HIGH voltage level

L = LOW voltage level

X = don’t care

↑ = LOW-to-HIGH level transition

2. The data output functions may be enabled or disabled by various signals at the OE and DIR inputs. Data input

functions are always enabled, i.e., data at the bus inputs will be stored on every LOW-to-HIGH transition on the clock

inputs.

September 1993

4

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