Product Specifications

• Dual Retriggerable Monostable Multivibrator with reset
• 16-Pin DIP
• Manufacturer - Phillips
• Manufacturer Part # - 74HC423N
• Integrated Circuit
• SKU# 007131

The 74HC423N are high-speed Si-gate CMOS devices and are pin compatible with Low power Schottky TTL (LSTTL). They are specified in compliance with JEDEC standard no.7A.

The 74HC423N are dual retriggerable monostable multivibrators with output pulse width control by three methods. The basic pulse time is programmed by selection of an external resistor (REXT ) and capacitor (CEXT ). The external resistor and capacitor are normally connected.

Once triggered, the basic output pulse width may be extended by retriggering the gated active LOW-going edge input (nA) or the active HIGH-going edge input (nB). By repeating this process, the output pulse period (nQ = HIGH, nQ = LOW) can be made as long as desired. Alternatively an output delay can be terminated at any time by a LOW-going edge on input nR_D, which also inhibits the triggering.

An internal connection from nR_D to the input gate makes it possible to trigger the circuit by a positive-going signal at input nR_D as shown in the function table. The basic output pulse width is essentially determined by the value of the external timing components R_EXT and C_EXT. When C_EXT ³ 10 nF, the typical output pulse width is defined as: t_W =R_EXT X C_EXT where t_W= pulse width in ns; R_EXT= external resistor in kW; C_EXT = external capacitor in pF. Schmitt-trigger action at all inputs makes the circuit highly tolerant to slower input rise and fall times. The �123� is identical to the �423� but can be triggered via the reset input.