SN74LS221NE4 Datasheet

Monostable Multivibrator


The SN74LS221NE4 devices are dual multivibrators with performance characteristics virtually identical to those of the ’121 devices. Each multivibrator features a negative-transitiontriggered 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 at 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, also is 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 maximum by choosing appropriate timing components. With Rext = 2 kΩ and Cext = 0, an output pulse typically of 30 ns is achieved that can be used as a dc-triggered reset signal. Output rise and fall times are TTL compatible and independent of pulse length. Typical triggering and clearing sequences are shown as a part of the switching characteristics waveforms.


[{"Name":" Operating Supply Voltage:","Value":"5 V"},{"Name":" Minimum Operating Temperature:","Value":"0 C"},{"Name":" Maximum Operating Temperature:","Value":"+ 70 C"},{"Name":"Supply Voltage - Max:","Value":"5.25 V"},{"Name":" Supply Voltage - Min:","Value":"4.75 V"},{"Name":"High Level Output Current:","Value":"- 0.4 mA"},{"Name":"Low Level Output Current:","Value":"8 mA"},{"Name":" Propagation Delay Time:","Value":"80 ns"},{"Name":"Elements per Chip:","Value":"2"},{"Name":"","Value":""}]

Manufacturer information


Electrification, automation and digitalization are the long-term growth fields of Siemens. In order to take full advantage of the market potential in these fields, our businesses are bundled into eight divisions and Siemens Healthineers as well as Siemens Wind Power as a separately managed businesses.

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