| 摘要 |
PROBLEM TO BE SOLVED: To solve the problem that A/D conversion operation is influenced by the superposition of serge voltage generated when comparing reference voltage to be applied to an analog input is obtained from a switching power supply in a comparing type A/D conversion. SOLUTION: A serge judgment circuit 13 judges whether serge voltage generated from a switching power supply 12 is not less than fixed level or not, and in a period that the serge voltage is held at the fixed level or more, stops the A/D conversion operation of an A/D conversion circuit 11. It is also available to obtain a signal synchronized with serge voltage and stop the A/D conversion operation by the signal in a serge voltage period. |
