5-552

FAST AND LS TTL DATA

SN74LS395

LOGIC DIAGRAM

S

Ds

CP

MR

OE

P0

P1

P2

P3

O0

O1

O2

O3 Q3

CP D

CD

Q

CP D

CD

Q

CP D

CD

Q

CP D

CD

Q

FUNCTION DESCRIPTION

The SN74LS395 contains four D-type edge-triggered

flip-flops and auxiliary gating to select a D input either from a

Parallel (Pn) input or from the preceding stage. When the

Select input is HIGH, the Pn inputs are enabled. A LOW signal

on the S input enables the serial inputs for shift-right opera-

tions, as indicated in the Truth Table.

State changes are initiated by HIGH-to-LOW transitions on

the Clock Pulse (CP) input. Signals on the Pn, Ds and S inputs

can change when the Clock is in either state, provided that the

recommended set-up and hold times are observed. When the

S input is LOW, a CP HIGH-LOW transition transfers data in

Q0 to Q1, Q1 to Q2, and Q2 to Q3. A left-shift is accomplished

by connecting the outputs back to the Pn inputs, but offset one

place to the left, i.e., O3 to P2, O2 to P1 and O1 to P0, with P3

acting as the linking input from another package.

When the OE input is HIGH, the output buffers are disabled

and the Q0–Q3 outputs are in a high impedance condition.

The shifting, parallel loading or resetting operations can still be

accomplished, however.

MODE SELECT — TRUTH TABLE

Inputs @ tn

Outputs @ tn+1

Operating Mode

MR

CP

S

Ds

Pn

O0

O1

O2

O3

Asynchronous Reset

L

X

X

X

X

L

L

L

L

Shift, SET First Stage

H

L

H

X

H

O0n

O1n

O2n

Shift, RESET First Stage

H

L

L

X

L

O0n

O1n

O2n

Parallel Load

H

H

X

Pn

P0

P1

P2

P3

H = HIGH Voltage Level

L = LOW Voltage Level

X = Immaterial

tn, n + 1 = time before and after CP HIGH-to-LOW transition

NOTE:

When OE is HIGH, outputs O0 – O3 are in the high impedance state; however, this does not affect other operations or the Q3 output.

GUARANTEED OPERATING RANGES

Symbol

Parameter

Min

Typ

Max

Unit

VCC

Supply Voltage

4.75

5.0

5.25

V

TA

Operating Ambient Temperature Range

0

25

70

°C

IOH

Output Current — High

– 0.4

mA

IOL

Output Current — Low

8.0

mA