| 摘要 |
PROBLEM TO BE SOLVED: To detect the charged voltage of a main capacitor without reducing the power supply voltage of a circuit on the CPU(central processing unit) side. SOLUTION: When the CPU detects the voltage of the main capacitor C1, at first, an IC control circuit 32 of an interface IC3 makes a comparison voltage generating part 33 generate a prescribed voltage and feeds it to a comparator 31 as a VREF voltage so that the voltage of the main capacitor C1 is detected using a method, whose detecting time is short but detecting accuracy is low and which detects the charged voltage of the main capacitor C1 by discriminating whether or not it is the prescribed voltage or more. When it is the prescribed voltage or more, the IC control circuit 32 makes the comparison voltage generating part 33 sequentially generate the voltage for A/D conversion and feeds them to the comparator 31 as the VREF voltage so that the voltage detection having high detection accuracy but taking a long detection time is performed by A/D conversion. |
