CD74HC4538-Q1
HIGH-SPEED CMOS LOGIC DUAL RETRIGGERABLE
PRECISION MONOSTABLE MULTIVIBRATOR
SCLS595A − NOVEMBER 2004 − REVISED APRIL 2008
D
D
D
D
D
D
D
D
D
D
Qualified for Automotive Applications
Retriggerable/Resettable Capability
Trigger and Reset Propagation Delays
D
D
Balanced Propagation Delay and Transition
Times
Significant Power Reduction Compared to
LSTTL Logic ICs
Independent of R , C
X
X
D
V
CC
Voltage = 2 V to 6 V
Triggering From the Leading or Trailing
Edge
D
High Noise Immunity N or N = 30% of
IL
IH
V
CC
, V = 5 V
CC
Q and Q Buffered Outputs Available
Separate Resets
M OR PW PACKAGE
(TOP VIEW)
Wide Range of Output Pulse Widths
Schmitt-Trigger Input on A and B Inputs
1CX
1RXCX
1R
VCC
1
2
3
4
5
6
7
8
16
15
14
13
12
11
Retrigger Time Is Independent of C
X
2CX
2RXCX
2R
2A
2B
Fanout (Over Temperature Range)
− Standard Outputs . . . 10 LSTTL Loads
− Bus Driver Outputs . . . 15 LSTTL Loads
1A
1B
1Q
1Q
description/ordering information
10 2Q
2Q
GND
9
The CD74HC4538 is a dual retriggerable/resettable
precision monostable multivibrator for fixed-voltage
timing applications. An external resistor (R ) and
X
external capacitor (C ) control the timing and accuracy for the circuit. Adjustment of R and C provides a wide
X
X
X
range of output pulse widths from the Q and Q terminals. The propagation delay from trigger input-to-output
transition and the propagation delay from reset input-to-output transition are independent of R and C .
X
X
Leading-edge triggering (A) and trailing-edge triggering (B) inputs are provided for triggering from either edge
of the input pulse. An unused A input should be tied to GND and an unused B input should be tied to V . On
CC
power up, the IC is reset. Unused resets and sections must be terminated. In normal operation, the circuit
retriggers on the application of each new trigger pulse. To operate in the nontriggerable mode, Q is connected
to B when leading-edge triggering (A) is used, or Q is connected to A when trailing-edge triggering (B) is used.
The period (τ) can be calculated from τ = (0.7) R , C ; R
is 5 kΩ. C
is 0 pF.
X
X
MIN
MIN
{
ORDERING INFORMATION
ORDERABLE
PART NUMBER
TOP-SIDE
‡
T
PACKAGE
A
MARKING
HC4538M
HC4538M
SOIC − M
Tape and reel
CD74HC4538QM96Q1
CD74HC4538QPWRQ1
−40°C to 125°C
TSSOP − PW Tape and reel
†
‡
For the most current package and ordering information, see the Package Option Addendum at the
end of this document, or see the TI web site at http://www.ti.com.
Package drawings, thermal data, and symbolization are available at http://www.ti.com/packaging.
Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of
Texas Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet.
Copyright 2008, Texas Instruments Incorporated
PRODUCTION DATA information is current as of publication date.
Products conform to specifications per the terms of Texas Instruments
standard warranty. Production processing does not necessarily include
testing of all parameters.
1
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