FEATURES
· Separate reset inputs
· Triggering from leading or trailing edge
· Output capability: standard
· ICC category: MSI
· Power-on reset on-chip
GENERAL DESCRIPTION
The 74HC/HCT4538 are high-speed Si-gate CMOS
devices and are pin compatible with “4538” of the “4000B”
series. They are specified in compliance with JEDEC
standard no. 7A.
The 74HC/HCT4538 are dual retriggerable-resettable
monostable multivibrators. Each multivibrator has an
active LOW trigger/retrigger input (nA0), an active HIGH
trigger/retrigger input (nA1) , an overriding active LOW
direct reset input (nRD), an output (nQ) and its complement
(nQ), and two pins (nCTC and nRCTC) for connecting the
external timing components Ct and Rt. Typical pulse width
variation over temperature range is ± 0.2%.
The “4538” may be triggered by either the positive or the
negative edges of the input pulse. The duration and
accuracy of the output pulse are determined by the
external timing components Ct and Rt. The output pulse
width (T) is equal to 0.7 ´ Rt ´ Ct. The linear design
techniques guarantee precise control of the output pulse
width.
A LOW level at nRD terminates the output pulse
immediately.
Schmitt-trigger action in the trigger inputs makes the circuit
highly tolerant to slower rise and fall times.