LOGIC DIAGRAM (ONE HALF SHOWN)

MS

CP

MR

4

12

1

15

2

14

K

CD

J

SD

Q

K

CD

J

Q

K

CD

J

SD

Q

3 Q0 13

5 Q1 11

6 Q2 10

7 Q3 9

K

CD

J

Q

TRUTH TABLE

CP

5-563

FAST AND LS TTL DATA

DUAL DECADE COUNTER

The SN54 / 74LS490 contains a pair of high-speed 4-stage ripple counters.

Each half of the SN54 / 74LS490 has individual Clock, Master Reset and Mas-

ter Set (Preset 9) inputs. Each section counts in the 8, 4, 2, 1 BCD code.

CONNECTION DIAGRAM DIP (TOP VIEW)

14

13

12

11

10

9

1

2

3

4

5

6

7

16

15

8

VCC

CPa

CPb MRb Q0b MSb

Q2b

Q1b

Q3b

MRa Q0a MSa Q1a Q2a Q3a GND

PIN NAMES

LOADING (Note a)

HIGH

LOW

MS

Master Set (Set to 9) Input

0.5 U.L.

0.25 U.L.

MR

Master Reset

0.5 U.L.

0.25 U.L.

CP

Clock Input (Active LOW Going Edge)

1.5 U.L.

1.5 U.L.

Q0 – Q3

Counter Outputs (Note b)

10 U.L.

5 (2.5) U.L.

NOTES:

a) 1 TTL Unit Load (U.L.) = 40

µA HIGH/1.6 mA LOW.

b) The Output LOW drive factor is 2.5 U.L. for Military (54) and 5 U.L. for Commercial

(74) Temperature Ranges.

OUTPUTS

COUNT

Q3

Q2

Q1

Q0

0

L

L

L

L

1

L

L

L

H

2

L

L

H

L

3

L

L

H

H

4

L

H

L

L

5

L

H

L

H

6

L

H

H

L

7

L

H

H

H

8

H

L

L

L

9

H

L

L

H

SN54/74LS490

DUAL DECADE COUNTER

LOW POWER SCHOTTKY

ORDERING INFORMATION

SN54LSXXXJ

Ceramic

SN74LSXXXN

Plastic

SN74LSXXXD

SOIC

J SUFFIX

CERAMIC

CASE 620-09

N SUFFIX

PLASTIC

CASE 648-08

16

1

16

1

16

1

D SUFFIX

SOIC

CASE 751B-03