December 1990

3

Philips Semiconductors

Product specification

4 x 4 register file; 3-state

74HC/HCT670

PIN DESCRIPTION

PIN NO.

SYMBOL

NAME AND FUNCTION

5, 4

read address inputs

8

GND

ground (0 V)

10, 9, 7, 6

data outputs

11

RE

3-state output read enable input (active LOW)

12

WE

write enable input (active LOW)

14, 13

write address inputs

15, 1, 2, 3

data inputs

16

positive supply voltage

Fig.1 Pin configuration.

Fig.2 Logic symbol.

Fig.3 IEC logic symbol.

Fig.4 Functional diagram.

WRITE MODE SELECT TABLE

Note

“internal latches” must be stable while WE is

LOW for conventional operation.

OPERATING

MODE

INPUTS

INTERNAL

WE

write data

L

L

L

H

L

H

data latched

H

X

no change

READ MODE SELECT TABLE

Notes

1. The selection of the “internal latches” by read address

H = HIGH voltage level

L = LOW voltage level

X = don’t care

Z = high impedance OFF-state

OPERATING

MODE

INPUTS

OUTPUT

RE

read

L

L

L

H

L

H

disabled

H

X

Z