HCF4536B

9/13

FUNCTIONAL TEST SEQUENCE

Test function has been included for the reduction

of test time required to exercise all 24 counter

stages.This test function divides the counter into

three 8-stage section and 255 counts are loaded in

each of the 8-stage sections in parallel. All

flip-flops are now at a "H". The counter is now

returned to the normal 24-steps in series

configuration. One more pulse is entered into In1

which will cause the counter to ripple from an all

"H" state to an all "L" state.

TEST CIRCUIT

FUNCTIONAL TEST SEQUENCE

Inputs

Outputs

COMMENTS

In 1

Set

Reset

8-Bypass

Decade Out

Q1 Thru

Q24

All 24 steps are in reset mode

HL

H

H

L

Counter is in three 8-stage section in parallel

mode

HH

HH

L

L

H

H

H

L

First "H" to "L" Transition of Clock

H

255 "H" to "L" transitions are clocked in the

counter

LH

H

H

L

H

H

H

H

The 255 "H" to "L" Transition

LL

LL

H

Counter converted back to 24 stages in series

mode.

Set and Reset must be connected together

and simultaneously go from "H" to "L"

HL

L

L

H

LL

LLL

Counter Ripples from an all "H" state to an all

"L" state