SN74ALS29845, SN74ALS29846

8BIT BUS INTERFACE DTYPE LATCHES WITH 3STATE OUTPUTS

SDAS150 − D3118 — JUNE 1988

POST OFFICE BOX 655303

Copyright

1

PRODUCTION DATA information is current as of

publication

date.

Products

conform

to

specifications per the terms of Texas Instruments

standard warranty. Production processing does not

necessarily include testing of all parameters.

Lines Directly

Necessary For Wider Address/Data Paths

or Buses With Parity

Loading

Outline” Packages, Plastic Chip Carriers,

and Standard Plastic 300-mil DIPs

Reliability

description

These 8-bit latches feature three-state outputs

designed specifically for driving highly capacitive

or relatively low-impedance loads. They are

particularly suitable for implementing buffer

registers, I/O ports, bidirectional bus drivers, and

working registers.

The eight latches are transparent D-type. The

′ALS29845 has noninverting data (D) inputs. The

′ALS29846 has inverting D inputs. Since CLR and

PRE are independent of the clock, taking the CLR

input low will cause the eight Q outputs to go low.

Taking the PRE input low will cause the eight Q

outputs to go high. When both PRE and CLR are

taken low, the outputs will follow the preset

condition.

The buffered output control inputs (OC1, OC2,

and OC3) can be used to place the eight outputs

in either a normal logic state (high or low levels) or

a high-impedance state. The outputs are also in

the high-impedance state during power-up and

power-down conditions. The outputs remain in the

high-impedance

state

while

the

device

is

powered-down. In the high-impedance state, the

outputs neither load nor drive the bus lines

significantly. The high-impedance state and

increased drive provide the capability to drive the

bus lines in a bus-organized system without need

SN74ALS29845 ...DW or NT Package

(Top View)

SN74ALS29846 . . . FN Package

(Top View)

SN74ALS29846 . . . DW or NT Package

(Top View)

1

2

3

4

5

6

7

8

9

10

11

12

24

23

22

21

20

19

18

17

16

15

14

13

OC1

OC2

1D

2D

3D

4D

5D

6D

7D

8D

CLR

GND

VCC

OC3

1Q

2Q

3Q

4Q

5Q

6Q

7Q

8Q

PRE

C

1

2

3

4

5

6

7

8

9

10

11

12

24

23

22

21

20

19

18

17

16

15

14

13

OC1

OC2

1D

2D

3D

4D

5D

6D

7D

8D

CLR

GND

VCC

OC3

1Q

2Q

3Q

4Q

5Q

6Q

7Q

8Q

PRE

C

SN74ALS29845 ...FN Package

(Top View)

32 1

28 27

12

5

6

7

8

9

10

11

25

24

23

22

21

20

19

2Q

3Q

4Q

NC

5Q

6Q

7Q

2D

3D

4D

NC

5D

6D

7D

426

13 14 15 16 17 18

32 1

28 27

12

5

6

7

8

9

10

11

25

24

23

22

21

20

19

2Q

3Q

4Q

NC

5Q

6Q

7Q

426

13 14 15 16 17 18

NC — No internal connection

2D

3D

4D

NC

5D

6D

7D