| 摘要 |
<p>PROBLEM TO BE SOLVED: To enable operation even when a battery voltage falls at the starting of an engine, etc., by boosting the voltage of a power source circuit to be inputted to drive a heating resistor. SOLUTION: At the cracking, etc., of a car's engine, a voltage of a battery 3 drops to about 5-6V, so an air flow meter 1 becomes inoperative. Therefor, with a booster circuit 10 comprising a DC-DC converter, the voltage is boosted to about 8V, for supplying a driving voltage for a heating resistor. With this, the driving voltage becomes stable at about as low as 3V of operation signal of the DC-DC converter, allowing operation in a wide range of battery voltage. For miniaturizing the DC-DC converter, the booster circuit 10 may be operated when the voltage of the battery 3 is below a specified value, and a battery voltage is used for driving above that. Thereby, the booster circuit 10 can be miniaturized.</p> |
