HEF4538B
Dual precision monostable multivibrator
Rev. 8 — 16 November 2011
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
EXT
and R
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
EXT
and R
EXT
. The output pulse width (t
W
) is equal to R
EXT
C
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
DD
power supply range of 3 V to 15 V referenced to V
SS
(usually ground). Unused inputs must be connected to V
DD
, V
SS
, or another input.
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
HEF4538BP
HEF4538BT
Package
Name
DIP16
SO16
Description
plastic dual in-line package; 16 leads (300 mil)
plastic small outline package; 16 leads; body width 3.9 mm
Version
SOT38-4
SOT109-1
PHILIPS [ NXP SEMICONDUCTORS ]
