HIT HD74HC674 Datasheet

HD74HC674

16-bit Shift Register

Description

The HD74HC674 is a 16-bit parallel-in, serial-out shift register. A three-state input/output (data I/O) port
provides access for entering serial data or reading the shift-register word in a recirculating loop.

The device has four basic modes of operation:

1. Hold (do nothing)

2. Write (serially via input/output)

3. Read (serially)

4. Load (parallel via data inputs)

Low-to-high-level changes at the chip select input should be made only when the clock input is low to
prevent false clocking.

Features

• High Speed Operation: tpd (CLK to SER/Q15) = 17 ns typ (CL = 50 pF)

• High Output Current: Fanout of 15 LSTTL Loads

• Wide Operating Voltage: VCC = 2 to 6 V

• Low Input Current: 1 µA max

• Low Quiescent Supply Current: ICC (static) = 4 µA max (Ta = 25°C)

Function Table

Inputs
CS R/W Mode CLK SER/Q

H X X X Z Do nothing
LLX Z Shift and write (serial load)
LHL Q
LHH P15Parallel load

14n

15

Operation

Shift and read

HD74HC674

Pin Arrangement

CLK

R/W

Mode

SER/Q

GND

CS

NC

15

P

P

P

P

P

1

2

3

4

5

6

7

0

8

1

9

2

10

3

11

4

12

24

23

22

21

20

19

18

17

16

15

14

13

V

CC

P

15

P

14

P

13

P

12

P

11

P

10

P

9

P

8

P

7

P

6

P

5

(Top view)

2

Logic Diagram

HD74HC674

IN
PE
CK

P

0

P

1

P

2

P

3

P

4

P

5

P

6

P

7

P

8

P

9

P

10

P

11

PQ

Mode

CLK
R/W

P

12

P

13

V

P

14

P

15

CC

SER/Q

15

CS

3