| 摘要 |
PROBLEM TO BE SOLVED: To provide a simple structure for measuring a battery voltage in a power source circuit, using a PWM-type switching regulator receiving the battery voltage as an input. SOLUTION: On-time of a switching transistor 23 of the PWM switching regulator 20 is measured digitally by a Ton time measuring part 12 with a load 11 at a constant load condition. Based on the result of the measurement, the battery voltage is detected by referring to a data table 13 in a table reference part 14. |
