| 摘要 |
PURPOSE:To previously send a precise reset signal when output DC voltage becomes lower than prescribed voltage to improve the reliability of a load supplying electric power by providing a reset signal generating circuit with a time constant circuit into a DC stabilizing circuit. CONSTITUTION:Input voltage VIN is applied to a DC stabilizing circuit REG for a DC stabilizing power unit, and after a prescribed period, prescribed output voltage is outputted. The electric power unit is provided with an input voltage detecting circuit consisting of a Zener diode ZD having a drop voltage equal to prescribed minimum input voltage, a capacitor C1 with prescribed time constant and a resistor R1 and said circuit detects the prescribed minimum input voltage and supplies the detected signal to a transistor TR1 at prescribed timing. At the voltage before the output of the circuit REG is returned to prescribed output voltage, a TR2 is turned on and a reset signal is outputted from a reset signal output terminal RST. At the time when the output DC voltage becomes the prescribed value, the TR1 is turned on and the sending of a reset signal is stopped. |
