74HC221N

产品概述

The 74HC221N is a dual non-retriggerable Monostable Multivibrator with a reset. It is pin compatible with the low power Schottky TTL (LSTTL). Each multivibrator features an active low-going edge input (nA) and an active high-going edge input (nB), either of which can be used as an enable input. Pulse triggering occurs at a particular voltage level and is not directly related to the transition time of the input pulse. Schmitt-trigger input circuitry for the nB inputs allow jitter-free triggering from inputs with slow transition rates, providing the circuit with excellent noise immunity. Once triggered, the outputs (nQ, nQ) are independent of further transitions of nA and nB inputs and are a function of the timing components. The output pulses can be terminated by the overriding active low reset inputs (nRD). Input pulses may be of any duration relative to the output pulse.

• Pulse width variance is typically less than ±5%
• Pin-out identical to "123"
• Overriding reset terminates output pulse
• nB Inputs have hysteresis for improved noise immunity
• Output capability - Standard (except for nREXT/CEXT)
• Complies with JEDEC standard No. 7A

应用

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