Initial clearing circuit

Abstract

Abstract PURPOSE:To ensure initial clearing regardless of the rise time of a power supply, by releasing the clear signal with a delay of a certain period after the power supply voltage reaches the prescribed level. CONSTITUTION:A constant voltage diode D41 is not conductive and transistors TRQ41 and TRQ42 are turned off and on respectively at a moment when the power supply voltage VCC is applied. Thus an input VIN of a Schmitt trigger inverter 1 has no rise, and an output inverter 2 delivers a clear signal. When the voltage VCC exceeds the Zener voltage of the diode D41, the TRQ41 and TRQ42 are turned on and off, respectively. Then a delaying circuit consisting of a resistance R44 and a capacitor C41 starts its operation. Thus the voltage VIN of the inverter 1 starts rising. The output of the inverter 1 releases the clear signal delivered from an output inverter 2 after a certain period that is decided by the time constant of the delaying circuit.

Inventors

• 👤 Noriyuki Tanaka
• 👤 宣幸 田中

Bibliographic Details