1

Data sheet acquired from Harris Semiconductor

SCHS195

Features

• Simultaneous and Independent Read and Write

Operations

• Expandable to 512 Words of n-Bits

• Three-State Outputs

• Organized as 4 Words x 4 Bits Wide

• Buffered Inputs

• Fanout (Over Temperature Range)

- Standard Outputs . . . . . . . . . . . . . . . 10 LSTTL Loads

- Bus Driver Outputs . . . . . . . . . . . . . 15 LSTTL Loads

• Balanced Propagation Delay and Transition Times

• Significant Power Reduction Compared to LSTTL

Logic ICs

• HC Types

- 2V to 6V Operation

• HCT Types

- 4.5V to 5.5V Operation

- Direct LSTTL Input Logic Compatibility,

Description

The Harris CD74HC670 and CD74HCT670 are 16-bit register

files organized as 4 words x 4 bits each. Read and write

address and enable inputs allow simultaneous writing into one

location while reading another. Four data inputs are provided

to store the 4-bit word. The write address inputs (WA0 and

WA1) determine the location of the stored word in the register.

When write enable (WE) is low the word is entered into the

address location and it remains transparent to the data. The

outputs will reflect the true form of the input data. When (WE)

is high data and address inputs are inhibited. Data acquisition

from the four registers is made possible by the read address

inputs (RA1 and RA0). The addressed word appears at the

output when the read enable (RE) is low. The output is in the

high impedance state when the (RE) is high. Outputs can be

tied together to increase the word capacity to 512 x 4 bits.

Pinout

CD74HC670, CD74HCT670

(PDIP, SOIC)

TOP VIEW

Ordering Information

14

15

16

9

13

12

11

10

1

2

3

4

5

7

6

8

D1

D2

D3

RA1

RA0

Q3

GND

Q2

WA0

WA1

WE

RE

Q0

Q1

D0

January 1998

CAUTION: These devices are sensitive to electrostatic discharge. Users should follow proper IC Handling Procedures.

Copyright

File Number

1660.1

CD74HC670,

CD74HCT670

High-Speed CMOS Logic

4x4 Register File

[ /Title

(CD74H

C670,

CD74H

CT670)

/Subject

(High-

Speed

CMOS

Logic

4x4 Reg-

ister