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Monostable multivibrators or one-shots are
digital logic devices that have only one stable state. By
contrast, flip-flops and latches are bistable devices that
can remain in either a set or reset state for an indefinite
period of time. Monostable multivibrators remain in their
stable state indefinitely, until an external input is
applied. Once triggered, the output is temporarily switched
to another state. Because they are timed devices, monostable
multivibrators can hold their unstable output state for only
a limited amount of time. With semiconductor monostable
circuits, this timing function is often accomplished through
the use of resistors and capacitors. In terms of a
mechanical analogy, monostable multivibrators are like
momentary contact pushbuttons that spring-return to a normal
(stable) position when pressure is moved from the button
actuator. Conversely, bistable devices such as flip-flops
and latches are like standard wall or toggle switches that
turn lights either on or off. |
