Philips Semiconductors

Product specification

74LVC161

Presettable synchronous 4-bit binary counter;

asynchronous reset

1998 May 20

4

FUNCTIONAL DIAGRAM

PARALLEL LOAD

CIRCUITRY

BINARY

COUNTER

34

56

TC 15

14

13

12

11

1 MR

2CP

7

CEP

CET

10

PE

9

SY00068

STATE DIAGRAM

8

7

6

5

4

12

11

10

9

13

14

15

0

1

2

3

SF00664

FUNCTION TABLE

OPERATING

INPUTS

OUTPUTS

MODES

MR

CP

CEP

CET

PE

Dn

Qn

TC

Reset (clear)

L

X

X

X

X

X

L

L

Parallel load

H

↑

X

X

l

l

L

L

Parallel load

H

↑

X

X

l

h

H

*

Count

H

↑

h

h

h

X

count

*

Hold

H

X

l

X

h

X

*

(do nothing)

H

X

X

l

h

X

L

NOTES:

*

=

The TC output is High when CET is High and the counter

is at Terminal Count (HHHH)

H

=

High voltage level

h

=

High voltage level one setup time prior to the Low-to-High

clock transition

L

=

Low voltage level

l

=

Low voltage level one setup time prior to the Low-to-High

clock transition

q

=

Lower case letters indicate the state of the referenced

output one setup time prior to the Low-to-High clock

transition

X

=

Don’t care

↑

=

Low-to-High clock transition

TYPICAL TIMING SEQUENCE

CP

PE

TC

MR

INHIBIT

COUNT

CEP

CET

D0

D2

D1

D3

Q0

Q2

Q1

Q3

RESET PRESET

12

13

14

15

0

1

2

SY00069

Typical timing sequence: reset outputs to zero; preset to binary

twelve; count to thirteen, fourteen, fifteen, zero, one, and two;

inhibit