SNJ54LS221W

The SNJ54LS221W from Texas Instruments is a dual monostable multivibrator designed for high stability. It offers performance characteristics virtually identical to the SN54121 and SN74121 one-shots, with a pinout that is identical to the SN54123, SN74123, SN54LS123, and SN74LS123.

Each multivibrator in the SNJ54LS221W features a negative-transition-triggered input and a positive-transition-triggered input, either of which can function as an inhibit input. The Schmitt-trigger input circuitry provides excellent noise immunity. The output pulse length can be varied by external timing components, with maximums of 49 ns for the SN54LS221 variant and 70 ns for the SN74LS221 variant.

This device is rated for military operating temperatures ranging from -55°C to 125°C. It is available in a CDIP package with through-hole mounting.

The '221 and 'LS221 devices are monolithic dual multivibrators with performance characteristics virtually identical to those of the '121 devices. Each multivibrator features a negative-transition-triggered input and a positive-transition-triggered input, either of which can be used as an inhibit 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 (TTL hysteresis) for B input allows jitter-free triggering from inputs with transition rates as slow as 1 V/s, providing the circuit with excellent noise immunity, typically of 1.2 V. A high immunity to VCC noise, typically of 1.5 V, is also provided by internal latching circuitry. Once fired, the outputs are independent of further transitions of the A and B inputs and are a function of the timing components, or the output pulses can be terminated by the overriding clear. Input pulses can be of any duration relative to the output pulse. Output pulse length can be varied from 35 ns to the maximums shown in the above table by choosing appropriate timing components. With Rext = 2 k and Cext = 0, an output pulse typ