SN54HC191, SN74HC191

4BIT SYNCHRONOUS UP/DOWN BINARY COUNTERS

SCLS121D − DECEMBER 1982 − REVISED OCTOBER 2003

7

POST OFFICE BOX 655303

timing requirements over recommended operating free-air temperature range (unless otherwise

noted)

VCC

TA = 25°C

SN54HC191

SN74HC191

UNIT

VCC

MIN

MAX

MIN

MAX

MIN

MAX

UNIT

2 V

4.2

2.8

3.3

fclock

Clock frequency

4.5 V

21

14

17

MHz

fclock

Clock frequency

6 V

24

16

19

MHz

2 V

120

180

150

LOAD low

4.5 V

24

36

30

tw

Pulse duration

LOAD low

6 V

21

31

26

ns

tw

Pulse duration

2 V

120

180

150

ns

CLK high or low

4.5 V

24

36

30

CLK high or low

6 V

21

31

26

2 V

150

230

188

Data before LOAD

↑

4.5 V

30

46

38

Data before LOAD

↑

6 V

25

38

32

2 V

205

306

255

CTEN before CLK

↑

4.5 V

41

61

51

tsu

Setup time

CTEN before CLK

↑

6 V

35

53

44

ns

tsu

Setup time

2 V

205

306

255

ns

D/U before CLK

↑

4.5 V

41

61

51

D/U before CLK

↑

6 V

35

53

44

2 V

150

225

190

LOAD inactive before CLK

↑

4.5 V

30

45

38

LOAD inactive before CLK

↑

6 V

25

38

32

2 V

5

5

5

Data after LOAD

↑

4.5 V

5

5

5

Data after LOAD

↑

6 V

5

5

5

2 V

5

5

5

th

Hold time

CTEN after CLK

↑

4.5 V

5

5

5

ns

th

Hold time

CTEN after CLK

↑

6 V

5

5

5

ns

2 V

5

5

5

D/U after CLK

↑

4.5 V

5

5

5

D/U after CLK

6 V

5

5

5