| 摘要 |
PURPOSE:To prevent assuredly an error signal output of a control circuit while a power supply is kept off, by holding the power supply voltage of a service interruption processing circuit for a period longer than the voltage of the control circuit. CONSTITUTION:The power supply voltage VCC1 drops lower than the prescribed voltage when the power supply is kept off, and a reset circuit 5 detects this voltage drop and delivers a reset signal to a control circuit. Then the voltage VCC2 keeps its level by the functions of a capacitor C2 and a diode D even if the level of the VCC1 drops further down to OV. Therefore a comparator CMP can deliver a perfect reset signal to the control circuit. In such a way, an error signal output of the control circuit is assuredly prevented while a power supply is kept off. |
