| 摘要 |
PROBLEM TO BE SOLVED: To improve the operation reliability of an equipment by providing a means connected to first and second voltage power sources for voltage-dividing a power supply voltage and the means for detecting the abnormality of the first and second voltage power sources based on the voltage-divided voltage. SOLUTION: Both terminals of a voltage divider circuit 10 are connected to a positive power supply voltage VP and a negative power supply voltage VN, and resistors R1 and R2 being constant impedance elements are connected in series to a Zener diode ZD being a constant voltage element in the voltage divider circuit 10. A voltage divided voltage Vs appearing at the common connection point of the resistors R1 and R2 is supplied to an A/D converter 12 and converted to digital data and a CPU 14 measures the value of the voltage divided voltage Vs by the data, checks the change and judges the abnormality. In this case, A/D conversion data at the time of a product initial stage are stored in an NVRAM 16 which is a nonvolatile positive memory cell beforehand and they are held. Then, the CPU 14 reads the initial data at the time of judging the abnormality and compares them with measured voltage division data. |
