SN54ALS646, SN54ALS648, SN54AS646

SN74ALS646A, SN74ALS648A, SN74AS646, SN74AS648

OCTAL BUS TRANSCEIVERS AND REGISTERS WITH 3-STATE OUTPUTS

SDAS039F – DECEMBER 1983 – REVISED JANUARY 1995

8

POST OFFICE BOX 655303

• DALLAS, TEXAS 75265

switching characteristics (see Figure 2)

PARAMETER

FROM

(INPUT)

TO

(OUTPUT)

VCC = 4.5 V to 5.5 V,

CL = 50 pF,

R1 = 500

Ω,

R2 = 500

Ω,

TA = MIN to MAX†

UNIT

SN54ALS646

SN74ALS646A

MIN

MAX

MIN

MAX

fmax

35

40

MHz

tPLH

CLKBA or CLKAB

AorB

10

35

7

30

ns

tPHL

CLKBA or CLKAB

A or B

5

20

5

17

ns

tPLH

AorB

BorA

5

22

3

20

ns

tPHL

A or B

B or A

3

15

3

12

ns

tPLH

SBA or SAB‡

AorB

10

40

7

35

ns

tPHL

(stored data low)

A or B

5

23

5

20

ns

tPLH

SBA or SAB‡

AorB

8

30

6

25

ns

tPHL

(stored data high)

A or B

5

24

5

20

ns

tPZH

OE

AorB

3

20

2

17

ns

tPZL

OE

A or B

5

22

4

20

ns

tPHZ

OE

AorB

1

12

1

10

ns

tPLZ

OE

A or B

1

20

2

16

ns

tPZH

DIR

AorB

5

38

3

30

ns

tPZL

DIR

A or B

5

30

4

25

ns

tPHZ

DIR

AorB

1

12

1

10

ns

tPLZ

DIR

A or B

2

21

2

16

ns

† For conditions shown MIN or MAX, use the appropriate value specified under recommended operating conditions.

‡ These parameters are measured with the internal output state of the storage register opposite that of the bus input.