1
Standard ICs
Dual precision monostable
multivibrator
BU4538B
The BU4538B is a monostable multivibrator that can be reset and retriggered. It is triggered from either edge of an
input pulse. As the output pulse width and accuracy are determined by the external timing constants Cx and Rx, a
wide range of accurate output pulse widths is available. Linear CMOS technology makes it possible to control the
output pulse width with greater accuracy. Determination is made based on tWOUT = Rx · Cx throughout the entire
power supply voltage range, eliminating the necessity for other coefficients.
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Features
1) Low power dissipation.
2) Wide range of operating power supply voltages.
3) High input impedance.
4) High fan-out.
5) Direct drive of 2 L-TTL inputs and 1 LS-TTL input.
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Block diagram
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Logic circuit diagram
2T2A
T1A
AA
BA
QA
Q
CD
T1
T2
Q
QA
CDA 3
4
5
6
7
8
15
14
13
12
11
10
9VSS
1
T1B
VDD
CDB
AB
BB
QB
T2B
QB
16
BA
Q
CD
T1
T2
Q
BA
VDD
RX
2 (14)
1 (15)
4 (12)
T1
Vref1 Enable
S R
Vref2
Reset Latch
QQ
Enable
A
B
CX
VDD
Control
Output
Latch
QS
QR
T2
CD
5 (11)
3 (13)
6 (10)
7 (9)
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Truth table
INPUT OUTPUT
ABCD Q Q
HH
LH L H
HL
LH
XXL L H
H