54LS123

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. 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 SN54 / 74LS123 (TOP VIEW) (SEE NOTES 1 THRU 4) V CC 1ĂR ext/ C ext 1 C ext 16 15 14 1Q 13 2Q 12 2 CLR 2B 11 10 2A 9 Q CLR Q CLR Q Q 1 2 3 4 5 6 7 8 1A 1B 1 CLR 1Q 2Q 2 C ext 2 R ext/ C ext GND SN54 / 74LS122 (TOP VIEW) (SEE NOTES 1 THRU 4) R ext/ V CC C ext NC C ext NC R int Q 14 13 12 11 10 9 8 R int Q Q CLR 1 A1 2 A2 NC Ċ NO INTERNAL CONNECTION. 3 B1 4 B2 5 CLR 6 Q 7 GND 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 obta...