| 摘要 |
PURPOSE:To set a reference voltage independently of a power supply voltage and to simplify the circuit constitution by using a Zener diode for power supply stabilization as the reference voltage to output a reset signal. CONSTITUTION:A Zener voltage VZ is generated across a Zener diode Q4 until a power supply voltage VCC1 drops to a value less than the sum between the voltage VZ and the voltage Vd. The Zener voltage VZ is generated across a Zener diode Q4. A non-inverting input of the comparator C1 references the Zener voltage. When the stabilized voltage VCC2 drops to a value below the sum between the Zener voltage VZ and a voltage VTH of a reference voltage source, the comparator C1 outputs a reset signal. Moreover, the voltage of the reference voltage source is set in this case smaller than the voltage Vd between the base and emitter of the TRQ1. |
