A20571S - SN74AHCT123APWR SMD Dual Retriggerable Multivibrator (TI)

These edge-triggered multivibrators feature output pulse-duration control by three methods. In the first method, the A\ input is low, and the B input goes high. In the second method, the B input is high, and the A\ input goes low. In the third method, the A\ input is low, the B input is high, and the clear (CLR)\ input goes high. The output pulse duration is programmed by selecting external resistance and capacitance values. The external timing capacitor must be connected between Cext and Rext/Cext (positive) and an external resistor connected between Rext/Cext and VCC. To obtain variable pulse durations, connect an external variable resistance between Rext/Cext and VCC. The output pulse duration also can be reduced by taking CLR\ low.
Pulse triggering occurs at a particular voltage level and is not directly related to the transition time of the input pulse. The A\, B, and CLR\ inputs have Schmitt triggers with sufficient hysteresis to handle slow input transition rates with jitter-free triggering at the outputs.
Once triggered, the basic pulse duration can be extended by retriggering the gated low-level-active (A\) or high-level-active (B) input. Pulse duration can be reduced by taking CLR\ low. CLR\ input can be used to override A\ or B inputs. The variance in output pulse duration from device to device typically is less than ?0.5% for given external timing components. During power up, Q outputs are in the low state, and Q\ outputs are in the high state. The outputs are glitch free, without applying a reset pulse.

Features:
Inputs Are TTL-Voltage Compatible
Schmitt-Trigger Circuitry On A\, B, and CLR\ Inputs for Slow Input Transition Rates
Edge Triggered From Active-High or Active-Low Gated Logic Inputs
Retriggerable for Very Long Output Pulses
Overriding Clear Terminates Output Pulse

TSSOP 16 package. Manufactured by Texas Instruments.
A20571S