STMicroelectronics M54HC123A
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. These inputs are valid for slow rising/falling signals, (tr = tf = I sec).| Part No. | M54HC123A |
|---|---|
| Datasheet | M54HC123A Download |
| Manufacturer |  STMicroelectronics |
| Description | DUAL RETRIGGERABLE MONOSTABLE MULTIVIBRATOR |
| Buy | Stock & Price |
DESCRIPTION
There are two trigger inputs, A INPUT (negative edge) and 8 INPUT (positive edge). 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 Cx ≥ 10nF and Rx ≥ 10KΩ, the output pulse width value is approssimatively given by the formula: tw(out) = K● Cx
● Rx. Two different pulse width constant are available: K ≅ 0.45 for HC123 K ≅ 1 for HC123A. Taking CLR low breaks this MONOSTABLE STATE. If the next trigger pulse occurs during the MONOSTABLEperiod it makes the MONOSTABLE period longer. Limit for values of Cx and Rx : Cx : NO LIMIT Rx : VCC < 3.0 V 5 K Ω to 1 M Ω VCC ≥ 3.0 V 1 K Ω to 1 M Ω All inputs are equipped with protection circuits PIN CONNECTIONS (top view) NC = No Internal Connection October 1993 1/14 M54/M74HC123/123A SYSTEM DIAGRAM TIMING CHART 2/14 M54/M74HC123/123A BLOCK DIAGRAM Note : (1) Cx, Rx, Dx are external components. (2) Dx is a clamping diode.
