CD74HC221PW (TEXAS INSTRUMENTS)

The CD74HC221PW is a dual Monostable Multivibrator with RESET. An external resistor (RX) and an external capacitor (CX) control the timing and the accuracy for the circuit. Adjustment of RX and CX provides a wide range of output pulse widths from the Q and Q terminals. Pulse triggering on the B input occurs at a particular voltage level and is not related to the rise and fall time of the trigger pulse. Once triggered, the outputs are independent of further trigger inputs on A and B. The output pulse can be terminated by a low level on the RESET (R) pin. Trailing edge triggering (A) and leading-edge-triggering (B) inputs are provided for triggering from either edge of the input pulse. On power up, the IC is RESET. If either Mono is not used each input (on the unused device) must be terminated either high or low. The minimum value of external resistance, RX, is typically 500R.