HEF4538B
Dual precision monostable multivibrator
Rev. 9 10 December 2013 Product data sheet
1. General description
The HEF4538B is a dual retriggerable-resettable monostable multivibrator. Each
multivibrator has an active LOW trigger/retrigger input (nA), an active HIGH
trigger/retrigger input (nB), an overriding active LOW direct reset input (nCD), an output
(nQ) and its complement (nQ), and two pins (nREXT/CEXT, and nCEXT, always
connected to ground) for connecting the external timing components C and R .
EXT EXT
Typical pulse width variation over the specified temperature range is 0.2 %.
The multivibrator may be triggered by either the positive or the negative edges of the input
pulse and will produce an accurate output pulse with a pulse width range of 10 s to
infinity. The duration and accuracy of the output pulse are determined by the external
timing components C and R . The output pulse width (t ) is equal to R C .
EXT EXT W EXT EXT
The linear design techniques in LOCMOS (Local Oxide CMOS) guarantee precise control
of the output pulse width. A LOW level at nCD terminates the output pulse immediately.
The trigger inputs Schmitt trigger action makes the circuit highly tolerant of slower rise
and fall times.
It operates over a recommended V power supply range of 3 V to 15 V referenced to V
DD SS
(usually ground). Unused inputs must be connected to V , V , or another input.
DD SS
2. Features and benefits
Tolerant of slow trigger rise and fall times
Fully static operation
5 V, 10 V, and 15 V parametric ratings
Standardized symmetrical output characteristics
Specified from 40 C to +85 C and 40 C to +125 C
Complies with JEDEC standard JESD 13-B
3. Ordering information
Table 1. Ordering information
All types operate from 40 C to +125 C.
Type number Package
Name Description Version
HEF4538BP DIP16 plastic dual in-line package; 16 leads (300 mil) SOT38-4
HEF4538BT SO16 plastic small outline package; 16 leads; body width 3.9 mm SOT109-1HEF4538B
NXP Semiconductors
Dual precision monostable multivibrator
4. Functional diagram
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Fig 1. Functional diagram
HEF4538B All information provided in this document is subject to legal disclaimers. NXP B.V. 2013. All rights reserved.
Product data sheet Rev. 9 10 December 2013 2 of 18
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