CD74HC123, CD74HCT123,
CD74HC423, CD74HCT423
S E M I C O N D U C T O R
High Speed CMOS Logic Dual Retriggerable
Monostable Multivibrators with Resets
September 1997
Features
Description
• Overriding Reset Terminates Output Pulse
• Triggering From the Leading or Trailing Edge
• Q and Q Buffered Outputs
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
• Separate Resets
external resistor (R ) and an external capacitor (C ) control
X
X
the timing and the accuracy for the circuit. Adjustment of Rx
• Wide Range of Output-Pulse Widths
• Schmitt Trigger on Both A and B Inputs
and C provides a wide range of output pulse widths from
X
the Q and 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.
• Fanout (Over Temperature Range)
- Standard Outputs. . . . . . . . . . . . . . . 10 LSTTL Loads
- Bus Driver Outputs . . . . . . . . . . . . . 15 LSTTL Loads
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.
o
o
• Wide Operating Temperature Range . . . -55 C to 125 C
• Balanced Propagation Delay and Transition Times
• Significant Power Reduction Compared to LSTTL
Logic ICs
• HC Types
The minimum value of external resistance, Rx is typically 5kΩ.
- 2V to 6V Operation
The minimum value external capacitance, C , is 0pF. The
X
calculation for the pulse width is t = 0.45 R C at V
= 5V.
- High Noise Immunity: N = 30%, N = 30%of V
IL IH CC
at
W
X X CC
V
= 5V
CC
Ordering Information
• HCT Types
- 4.5V to 5.5V Operation
PKG.
NO.
o
PART NUMBER TEMP. RANGE ( C) PACKAGE
- Direct LSTTL Input Logic Compatibility,
V = 0.8V (Max), V = 2V (Min)
IL IH
CD74HC123E
CD74HCT123E
CD74HC423E
CD74HCT423E
CD74HC123M
CD74HCT123M
CD74HC423M
CD74HCT423M
NOTES:
-55 to 125
-55 to 125
-55 to 125
-55 to 125
-55 to 125
-55 to 125
-55 to 125
-55 to 125
16 Ld PDIP
16 Ld PDIP
16 Ld PDIP
16 Ld PDIP
E16.3
E16.3
E16.3
E16.3
- CMOS Input Compatibility, I ≤ 1µA at V , V
OL OH
l
Pinout
CD74HC123, CD74HCT123, CD74HC423, CD74HCT423
(PDIP, SOIC)
TOP VIEW
16 Ld SOIC M16.15
16 Ld SOIC M16.15
16 Ld SOIC M16.15
16 Ld SOIC M16.15
1A
1B
1R
1Q
2Q
1
2
3
4
5
6
7
8
16 V
CC
15 1R C
X
X
14 1C
X
13 1Q
12 2Q
11 2R
10 2B
1. When ordering, use the entire part number. Add the suffix 96 to
obtain the variant in the tape and reel.
2C
X
X
2R C
2. Wafer or die for this part number is available which meets all elec-
trical specifications. Please contact your local sales office or
Harris customer service for ordering information.
X
9
2A
GND
CAUTION: These devices are sensitive to electrostatic discharge. Users should follow proper IC Handling Procedures.
File Number 1708.1
Copyright © Harris Corporation 1997
1