SN54LV123A

SN74LV123A

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SCLS393Q – APRIL 1998 – REVISED AUGUST 2015

9 Detailed Description

9.1 Overview

The SNx4LV123A devices contain two independent monostable multivibrators. They produce a specific width

high output pulse when triggered (Q is normally high, pulse is low). The device uses an external RC circuit to

determine the output pulse length, which is explained in detail in the Application Information section.

Pulse triggering occurs at a particular voltage level and is not directly related to the transition time of the input

pulse. The A, B, and CLR inputs have Schmitt triggers with sufficient hysteresis to handle slow input transition

rates with jitter-free triggering at the outputs.

Once triggered, the basic pulse duration can be extended by retriggering the gated low-level-active (A) or high-

level-active (B) input. Pulse duration can be reduced by taking CLR low. The Figure 7 illustrates pulse control by

retriggering the inputs and early clearing.

During power-up, Q outputs are in the low state, and Q outputs are in the high state. The outputs are glitch free,

without applying a reset pulse.

outputs, preventing damaging current backflow through the device when it is powered down.

Pin assignments for these devices are identical to those of the 'AHC123A and 'AHCT123A devices for

interchangeability, when allowed.

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