M74HC123

The M54/74HC123 is a high speed CMOS MONOSTABLE multivibrator fabricated with silicon gate C2MOS technology. It achieves the high speed operation similar to equivalent LSTTL while maintaining the CMOS low power dissipation. There are two trigger inputs,A INPUT (negative edge) and 8 INPUT (positive edge). These inputs are valid for slow rising/falling signals, (tr = tf = I sec). The device may also be triggered by using the CLR input (positive- edge) because of the Schmitt-trigger input ; after triggering the output maintains the MONOSTABLE state for the time period determined by the external resistor Rx and capacitor Cx. When Cx10nF and Rx . 10KW, the output pulse width value is approssimatively given by the formula: t_w(out) = K • Cx • Rx.

Two different pulse width constant are available: K0.45 for HC123 K1 for HC123A. Taking CLR  low breaks this MONOSTABLE STATE. If the next trigger pulse occurs during the MONOSTABLEperiod itmakes theMONOSTABLE period longer. Limit for values of Cx and Rx : Cx : NO LIMIT Rx : VCC < 3.0 V 5 K to 1 M VCC . 3.0 V 1 Kto 1 M

All inputs are equipped with protection circuits