74LV423
74LV423 is Dual retriggerable monostable multivibrator manufactured by Philips Semiconductors.
FEATURES
- Optimized for Low Voltage applications: 1.0 to 5.5V
- Accepts TTL input levels between VCC = 2.7V and VCC = 3.6V
- Typical VOLP (output ground bounce) t 0.8V @ VCC = 3.3V,
- Typical VOHV (output VOH undershoot) u 2V @ VCC = 3.3V,
- DC triggered from active HIGH or active LOW inputs
- Retriggerable for very long pulses up to 100% duty factor
- Direct reset terminates output pulses
- Schmitt-trigger action on all inputs except for the reset input
- Output capability: standard (except for n REXT/CEXT)
- ICC category: MSI
Tamb = 25°C Tamb = 25°C
DESCRIPTION
The 74LV423 is a low-voltage Si-gate CMOS device and is pin and function patible with the 74HC/HCT423. The 74LV423 is a dual retriggerable monostable multivibrator with output pulse width control by three methods. The basic pulse time is programmed by selection of an external resistor (REXT) and capacitor (CEXT). They are normally connected as shown in Figure 1. Once triggered, the basic output pulse width may be extended by retriggering the gated active LOW-going edge input (n A) or the active HIGH-going edge input (n B). By repeating this process, the output pulse period (n Q = HIGH, n Q = 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 n RD, which also inhibits the triggering. Figures 2 and 3 illustrate pulse control by retriggering and early reset. The basic output pulse width is essentially determined by the values of the external timing ponents REXT and CEXT. For pulse width when CEXT <10000p F, see Figure 6. When CEXT u 10,000p F, the typical output pulse width is defined as: t W = 0.45 REXT CEXT (typ.), where t W = pulse width in ns; REXT = external resistor in KΩ; and CEXT = external capacitor in p F. Schmitt-trigger action in the n A and n B inputs makes the circuit highly tolerant of slower input rise and fall times.
QUICK REFERENCE DATA
GND = 0V; Tamb = 25°C; tr = tf v2.5 ns SYMBOL PARAMETER Propagation delay n A, n B to n Q, n Q...
