The Harris CD74HC123, CD74HCT123, CD74HC423 and
CD74HCT423 are dual monostable multivibrators with
resets. They are all retriggerable and differ only in that the
123 types can be triggered by a negative to positive reset
pulse; whereas the 423 types do not have this feature. An
external resistor (R
) and an external capacitor (CX) control
X
the timing and the accuracy for the circuit. Adjustment of Rx
and C
the Q and
provides a wide range of output pulse widths from
X
Q terminals. Pulse triggering on the A and B
inputs occur at a particular voltage level and is not related to
the rise and fall times of the trigger pulses.
Once triggered, the output pulse width may be extended by
retriggering inputs
A and B. The output pulse can be
terminated by a LOW level on the Reset (R) pin. Trailing
edge triggering (
A) and leading edge triggering (B) inputs
are provided for triggering from either edge of the input
pulse. If either Mono is not used each input on the unused
device (
A, B, and R) must be terminated high or low.
The minimum value of external resistance, Rx is typically 5kΩ.
The minimum value external capacitance, C
calculation for the pulse width is t
= 0.45 RXCX at VCC = 5V.
W
, is 0pF. The
X
Ordering Information
PKG.
PART NUMBER TEMP. RANGE (oC) PACKAGE
CD74HC123E-55 to 12516 Ld PDIPE16.3
CD74HCT123E-55 to 12516 Ld PDIPE16.3
NO.
Pinout
CD74HC123, CD74HCT123, CD74HC423, CD74HCT423
(PDIP, SOIC)
TOP VIEW
16
1
1A
2
1B
3
1R
4
1Q
5
2Q
6
2C
X
2R
7
XCX
8
GND
CAUTION: These devices are sensitive to electrostatic discharge. Users should follow proper IC Handling Procedures.
Copyright
CD74HC423E-55 to 12516 Ld PDIPE16.3
CD74HCT423E-55 to 12516 Ld PDIPE16.3
CD74HC123M-55 to 12516 Ld SOICM16.15
CD74HCT123M-55 to 12516 Ld SOICM16.15
CD74HC423M-55 to 12516 Ld SOICM16.15
CD74HCT423M-55 to 12516 Ld SOICM16.15
NOTES:
1. When ordering, use the entire part number. Add the suffix 96 to
obtain the variant in the tape and reel.
2. Wafer ordiefor this partnumber is availablewhichmeets all electrical specifications. Please contact your local sales office or
Harris customer service for ordering information.
1
File Number 1708.1
CD74HC123, CD74HCT123, CD74HC423, CD74HCT423
Functional Diagram
1A
1B
1R
2R
2A
2B
1415
1Cx1RxCx
1
2
3
11
9
10
MONO 1
MONO 2
2Cx2RxCx
67
1Cx1Rx
2Cx2Rx
V
13
4
5
12
V
TRUTH TABLE
INPUTSOUTPUTS
ABRQQ
CD74HC/HCT123
CC
1Q
1Q
2Q
2Q
CC
HXHLH
XLHLH
L↑H
↓HH
XXLLH
LH↑
CD74HC/HCT423
HXHLH
XLHLH
L↑H
↓HH
XXLLH
NOTE: H = High Voltage Level, L = Low Voltage Level,
X = Don’t Care.
CAUTION: Stresses above those listed in “Absolute Maximum Ratings” may cause permanent damage to the device. This is a stress only rating and operation
of the device at these or any other conditions above those indicated in the operational sections of this specification is not implied.
NOTE:
3. θJA is measured with the component mounted on an evaluation PC board in free air.
Prerequisite for Switching Specifications (Continued)
25oC-40oC TO 85oC-55oC TO 125oC
PARAMETERSYMBOL VCC(V)
Rt
WL
2100--125--150-150ns
UNITSMINTYPMAXMINTYPMAXMINTYPMAX
4.520--25--30-30ns
617--21--26-26ns
A and B Hold Timet
H
250--65--75-75ns
4.510--13--15-15ns
69--11--13-13ns
Reset Removal Timet
REM
250--65--75-75ns
4.510--13--15-15ns
69--11--13-13ns
Retrigger Time Numbert
rT
5---------ns
RX = 10KΩ, CX = 0-50--63--76-ns
Output Pulse Widtht
W
5
Q or Q
RX= 10KΩ,CX= 10nF40-5038.7-51.338.2-51.8µs
HCT TYPES
Minimum Input,
Pulse Widtht
WL
5
-
A20--25--30--ns
BtWH20--25--30--ns
Rt
A and B Hold Timet
Reset Removal Timet
WL
H
REM
510--13- -15--ns
510--13- -15-ns
20--25--30--ns
Retrigger Time Number
(Note 4)
RX = 10KΩ, CX = 0t
Output Pulse Width Q or Qt
rT
W
5-50--63--76-ns
540-5038.7-51.338.2-51.8µs
RX= 10KΩ,CX= 10nF
NOTE:
4. Time to trigger depends on the values of RX and CX. The output pulse width can only be extended when the time between the activegoing edges of the trigger input pulses meet the minimum retrigger time requirement.
FIGURE 4. TYPICAL OUTPUT PULSE WIDTH AS A FUNCTION
OF CX FOR RX = 10kΩ AND 100kΩ
FIGURE 5. TYPICAL “K” FACTOR AS A FUNCTION OF V
7
CC
IMPORTANT NOTICE
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any product or service without notice, and advise customers to obtain the latest version of relevant information
to verify, before placing orders, that information being relied on is current and complete. All products are sold
subject to the terms and conditions of sale supplied at the time of order acknowledgement, including those
pertaining to warranty, patent infringement, and limitation of liability.
TI warrants performance of its semiconductor products to the specifications applicable at the time of sale in
accordance with TI’s standard warranty. Testing and other quality control techniques are utilized to the extent
TI deems necessary to support this warranty . Specific testing of all parameters of each device is not necessarily
performed, except those mandated by government requirements.
CERTAIN APPLICATIONS USING SEMICONDUCTOR PRODUCTS MAY INVOLVE POTENTIAL RISKS OF
DEATH, PERSONAL INJURY, OR SEVERE PROPERTY OR ENVIRONMENTAL DAMAGE (“CRITICAL
APPLICATIONS”). TI SEMICONDUCTOR PRODUCTS ARE NOT DESIGNED, AUTHORIZED, OR
WARRANTED TO BE SUITABLE FOR USE IN LIFE-SUPPORT DEVICES OR SYSTEMS OR OTHER
CRITICAL APPLICA TIONS. INCLUSION OF TI PRODUCTS IN SUCH APPLICATIONS IS UNDERST OOD TO
BE FULLY AT THE CUSTOMER’S RISK.
In order to minimize risks associated with the customer’s applications, adequate design and operating
safeguards must be provided by the customer to minimize inherent or procedural hazards.
TI assumes no liability for applications assistance or customer product design. TI does not warrant or represent
that any license, either express or implied, is granted under any patent right, copyright, mask work right, or other
intellectual property right of TI covering or relating to any combination, machine, or process in which such
semiconductor products or services might be or are used. TI’s publication of information regarding any third
party’s products or services does not constitute TI’s approval, warranty or endorsement thereof.
Copyright 1998, Texas Instruments Incorporated
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