Features
• Overriding Reset Terminates Output Pulse
• Triggering From the Leading or Trailing Edge
• Q and Q Buffered Outputs
• Separate Resets
• Wide Range of Output-Pulse Widths
• Schmitt Trigger on Both A and B Inputs
• Fanout (Over Temperature Range)
- Standard Outputs . . . . . . . . . . . . . . . 10 LSTTL Loads
- Bus Driver Outputs . . . . . . . . . . . . . 15 LSTTL Loads
• Wide Operating Temperature Range . . . -55oC to 125oC
• Balanced Propagation Delay and Transition Times
• Significant Power Reduction Compared to LSTTL
Logic ICs
• HC Types
- 2V to 6V Operation
- High Noise Immunity: NIL = 30%, NIH = 30%of VCC at
VCC = 5V
• HCT Types
- 4.5V to 5.5V Operation
- Direct LSTTL Input Logic Compatibility,
VIL= 0.8V (Max), VIH = 2V (Min)
- CMOS Input Compatibility, Il ≤ 1μA at VOL, VOH

Description
The ’HC123, ’HCT123, 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 (RX)
and an external capacitor (CX) control the timing and the
accuracy for the circuit. Adjustment of Rx and CX provides a
wide range of output pulse widths from 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.
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, CX, is 0pF.
The calculation for the pulse width is tW = 0.45 RXCX at
VCC = 5V.