SN54/74LS122 SN54/74LS123 RETRIGGERABLE MONOSTABLE MULTIVIBRATORS These dc triggered multivibrators feature pulse width control by three methods. 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 basic 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.
• • • • •
RETRIGGERABLE MONOSTABLE MULTIVIBRATORS LOW POWER SCHOTTKY
Overriding Clear Terminates Output Pulse Compensated for VCC and Temperature Variations DC Triggered from Active-High or Active-Low Gated Logic Inputs Retriggerable for Very Long Output Pulses, up to 100% Duty Cycle Internal Timing Resistors on LS122
J SUFFIX CERAMIC CASE 620-09 16 1
SN54 / 74LS123 (TOP VIEW) (SEE NOTES 1 THRU 4) 1 Rext/ 1 VCC Cext Cext 16 15 14
1Q
2Q
2 CLR
13
12
11
CLR Q 2 1B
3 1 CLR
2A
10
9
16 1
CLR Q
Q
1 1A
2B
16
Q 4 1Q
5 2Q
1
6 2 Cext
8 7 2 GND Rext/ Cext
Rext/ Cext
NC
13
12
Cext 11
NC
Rint 9
10
D SUFFIX SOIC CASE 751B-03
J SUFFIX CERAMIC CASE 632-08 14
SN54 / 74LS122 (TOP VIEW) (SEE NOTES 1 THRU 4) VCC 14
N SUFFIX PLASTIC CASE 648-08
1
Q N SUFFIX PLASTIC CASE 646-06
8
Rint Q
14 1
CLR Q 1 A1
2 A2
3 B1
4 B2
5 CLR
6 Q
7 GND
14 1
D SUFFIX SOIC CASE 751A-02
NC — NO INTERNAL CONNECTION. 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.
FAST AND LS TTL DATA 5-1
ORDERING INFORMATION SN54LSXXXJ SN74LSXXXN SN74LSXXXD
Ceramic Plastic SOIC