CD54HC646, CD74HCT646

OCTAL BUS TRANSCEIVERS AND REGISTERS

WITH 3-STATE OUTPUTS

SCHS278B – APRIL 2003 – REVISED APRIL 2003

7

POST OFFICE BOX 655303

• DALLAS, TEXAS 75265

HCT INPUT LOADING TABLE

INPUT

UNIT LOAD†

OE

1.3

DIR

0.75

CLKAB or CLKBA

0.6

SAB or SBA

0.45

A or B

0.3

† Unit Load is

∆ICC limit specified in

electrical characteristics table (e.g.,

360

µA max at 25°C).

timing requirements for CD54HC646 over recommended operating free-air temperature range

(unless otherwise noted) (see Figure 2)

VCC

TA = 25°C

TA = –55°C

TO 125

°C

TA = –40°C

TO 85

°C

UNIT

CC

MIN

MAX

MIN

MAX

MIN

MAX

2 V

6

4

5

fclock

Clock frequency

4.5 V

30

20

25

MHz

6 V

35

23

29

2 V

80

120

100

tw

Pulse duration, CLKBA or CLKAB high or low

4.5 V

16

24

20

ns

6 V

14

20

17

↑

↑

2 V

60

90

75

tsu

Setup time, A before CLKAB

↑ or B before CLKBA↑

4.5 V

12

18

15

ns

6 V

10

15

13

↑

↑

2 V

35

55

45

th

Hold time, A after CLKAB

↑ or B after CLKBA↑

4.5 V

7

11

9

ns

6 V

6

9

8

timing requirements for CD74HCT646 over recommended operating free-air temperature range,

VCC = 4.5 V (unless otherwise noted) (see Figure 3)

TA = 25°C

TA = –55°C

TO 125

°C

TA = –40°C

TO 85

°C

UNIT

MIN

MAX

MIN

MAX

MIN

MAX

fclock

Clock frequency

25

17

20

MHz

tw

Pulse duration, CLKBA or CLKAB high or low

25

38

31

ns

tsu

Setup time, A before CLKAB

↑ or B before CLKBA↑

12

18

15

ns

th

Hold time, A after CLKAB

↑ or B after CLKBA↑

5

5

5

ns