SN74LS164

3

LOGIC DIAGRAM

Q6

Q7

A

B

Q0

Q1

Q3

Q2

Q5

Q4

MR

CP

DQ

CD

DQ

CD

DQ

CD

DQ

CD

DQ

CD

DQ

CD

DQ

CD

DQ

CD

6

3

4

5

11

12

10

13

VCC = PIN 14

GND = PIN 7

= PIN NUMBERS

1

2

8

9

FUNCTIONAL DESCRIPTION

The LS164 is an edge-triggered 8-bit shift register with

serial data entry and an output from each of the eight stages.

Data is entered serially through one of two inputs (A or B);

either of these inputs can be used as an active HIGH Enable

for data entry through the other input. An unused input must

be tied HIGH, or both inputs connected together.

Each LOW-to-HIGH transition on the Clock (CP) input

shifts data one place to the right and enters into Q0 the logical

AND of the two data inputs (A

•B) that existed before the

rising clock edge. A LOW level on the Master Reset (MR)

input overrides all other inputs and clears the register

asynchronously, forcing all Q outputs LOW.

MODE SELECT — TRUTH TABLE

OPERATING

MODE

INPUTS

OUTPUTS

MODE

MR

A

B

Q0

Q1–Q7

Reset (Clear)

L

X

X

L

L – L

H

I

I

L

q0 –q6

Shift

H

I

h

L

q0 –q6

H

h

I

L

q0 –q6

H

h

h

H

q0 –q6

L (l) = LOW Voltage Levels

H (h) = HIGH Voltage Levels

X = Don’t Care

qn = Lower case letters indicate the state of the referenced input or output one

qn = set-up time prior to the LOW to HIGH clock transition.

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