Nexperia

74HC191

Presettable synchronous 4-bit binary up/down counter

Table 4. TC and RC Function table

H = HIGH voltage level; L = LOW voltage level; X = don’t care;

= one LOW level pulse;

= TC goes LOW on a LOW-to-HIGH clock transition.

Input

Terminal count state

Output

U/D

CE

CP

Q0

Q1

Q2

Q3

TC

RC

H

H

X

H

H

H

H

L

H

L

H

X

H

H

H

H

H

H

L

L

H

H

H

H

L

H

X

L

L

L

L

L

H

H

H

X

L

L

L

L

H

H

H

L

L

L

L

L

aaa-024379

CP

CLOCK

ENABLE

DIRECTION

CONTROL

CE

U/D

RC

CP

CE

U/D

RC

CP

CE

U/D

RC

Fig. 5. N-stage ripple counter using ripple clock

aaa-024380

CP

ENABLE

CLOCK

DIRECTION

CONTROL

CE

U/D

RC

CP

CE

U/D

RC

CP

CE

U/D

RC

Fig. 6. Synchronous n-stage counter using ripple carry/borrow

aaa-024381

CP

ENABLE

CLOCK

DIRECTION

CONTROL

CE

U/D

TC

CP

CE

U/D

CP

CE

U/D

TC

TC

Fig. 7. Synchronous n-stage counter with parallel gated carry/borrow

74HC191

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© Nexperia B.V. 2021. All rights reserved

Product data sheet

Rev. 6 — 8 September 2021

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