SN74ALS679

12-BIT ADDRESS COMPARATOR

SDAS003C – JUNE 1982 – REVISED JANUARY 1995

Copyright

1

POST OFFICE BOX 655303

Small-Outline (DW) Packages and Standard

Plastic (N) 300-mil DIPs

description

This

12-bit

address

comparator

simplifies

addressing of memory boards and/or other

peripheral devices. The four P inputs are normally

hardwired with a preprogrammed address. An

internal

decoder

determines

what

input

information applied to the A inputs must be low or

high to cause a low state at the Y output. For

example, a positive-logic bit combination of 0111

(decimal 7) at the P input determines that inputs A1 through A7 must be low and that inputs A8 through A12 must

be high to cause the output to go low. Equality of the address applied at the A inputs to the preprogrammed

address is indicated by the output being low.

This device features an enable (G) input. When G is low, the device is enabled. When G is high, the device is

disabled and the output is high, regardless of the A and P inputs.

The SN74ALS679 is characterized for operation from 0

°C to 70°C.

FUNCTION TABLE

INPUTS

OUTPUT

G

P3

P2

P1

P0

A1

A2

A3

A4

A5

A6

A7

A8

A9

A10

A11

A12

Y

L

L

L

L

L

H

H

H

H

H

H

H

H

H

H

H

H

L

L

L

LL

H

L

H

HHHH

HHH

H

H

H

L

L

L

LHL

L

L

HHHH

HHH

H

H

H

L

L

L

LH

HL

L

L

HHH

HHH

H

H

H

L

L

L

H

L

L

L

L

L

L

H

H

H

H

H

H

H

H

L

L

L

HL

H

L

L

LLL

H

H

H

H

H

H

H

L

L

L

HH

L

L

L

LLLL

H

H

H

H

H

H

L

L

L

HH

H

L

L

LLLL

L

H

H

H

H

H

L

L

H

L

L

L

L

L

L

L

L

L

L

L

H

H

H

H

L

L

H

LL

H

L

L

LLLL

LLL

H

H

H

L

L

H

LHL

L

L

LLLL

LLL

L

H

H

L

L

H

LH

HL

L

LLLL

LLL

L

L

H

L

L

H

H

L

L

L

L

L

L

L

L

L

L

H

H

H

L

L†

L

H

H

L

H

L

L

L

L

L

L

L

L

L

H

H

L

L†

L

H

H

H

L

L

L

L

L

L

L

L

L

L

L

H

L

L†

L

H

H

H

H

L

L

L

L

L

L

L

L

L

L

L

L

L

L

All other combinations

H

H

Any combination

H

† The three shaded rows of the function table show combinations that would normally not be used in address

comparator applications. The logic symbols above are not valid for these combinations in which P = 12, 13, and 14.

If symbols valid for all combinations are required, starting with the fourth exclusive-OR from the bottom, change P

≥ 9

to P = 9...11/13 . . . 15, P

≥ 10 to P = 10/11/14/15, and P ≥ 11 to P = 11/15.

DW OR N PACKAGE

(TOP VIEW)

1

2

3

4

5

6

7

8

9

10

20

19

18

17

16

15

14

13

12

11

A1

A2

A3

A4

A5

A6

A7

A8

A9

GND

G

Y

P3

P2

P1

P0

A12

A11

A10

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.