5-197

FAST AND LS TTL DATA

RETRIGGERABLE MONOSTABLE

MULTIVIBRATORS

These dc triggered multivibrators feature pulse width control by three meth-

ods. The basic pulse width is programmed by selection of external resistance

and capacitance values. The LS122 has an internal timing resistor that allows

the circuits to be used with only an external capacitor. Once triggered, the ba-

sic pulse width may be extended by retriggering the gated low-level-active (A)

or high-level-active (B) inputs, or be reduced by use of the overriding clear.

SN54 / 74LS122 (TOP VIEW)

(SEE NOTES 1 THRU 4)

SN54 / 74LS123 (TOP VIEW)

(SEE NOTES 1 THRU 4)

NOTES:

1. An external timing capacitor may be connected between Cext and Rext/Cext (positive).

2. To use the internal timing resistor of the LS122, connect Rint to VCC.

3. For improved pulse width accuracy connect an external resistor between Rext/Cext and

VCC with Rint open-circuited.

4. To obtain variable pulse widths, connect an external variable resistance between Rint/Cext

and VCC.

14

13

12

11

10

9

1

2

3

4

5

6

8

7

VCC

Rext/

Cext NC Cext NC Rint

Q

A1

A2

B1

B2

CLR

Q

GND

CLR Q

Q

Rint

2

Rext/

Cext

1

Cext

1Rext/

Cext

14

13

12

11

10

9

1

2

3

4

5

6

7

16

15

8

VCC

1A

1Q

2Q

2B

2

CLR

2A

1B

1

CLR

1Q

2Q

2

Cext

GND

Q

Q

Q

Q

CLR

CLR

NC NO INTERNAL CONNECTION.

SN54/74LS122

SN54/74LS123

RETRIGGERABLE MONOSTABLE

MULTIVIBRATORS

LOW POWER SCHOTTKY

J SUFFIX

CERAMIC

CASE 620-09

N SUFFIX

PLASTIC

CASE 648-08

16

1

16

1

ORDERING INFORMATION

SN54LSXXXJ

Ceramic

SN74LSXXXN

Plastic

SN74LSXXXD

SOIC

16

1

D SUFFIX

SOIC

CASE 751B-03

J SUFFIX

CERAMIC

CASE 632-08

N SUFFIX

PLASTIC

CASE 646-06

14

1

14

1

14

1

D SUFFIX

SOIC

CASE 751A-02