| 摘要 |
PROBLEM TO BE SOLVED: To achieve a switching power source at a low cost and with simple circuit configuration.SOLUTION: A switching control IC20 is an IC that switching-controls a DC-DC converter 10, starts at a first set voltage, and is able to continue operation at a voltage equal to or higher than a second set voltage lower than the first set voltage. A voltage supply circuit 50 supplies a power source voltage to switching control IC20 on the basis of an auxiliary power source voltage set to the second set voltage or higher but lower than the first set voltage. The voltage supply circuit 50 supplies, at the start of the switching control IC20, a power source voltage equal to or higher than the first set voltage during start of the switching control IC20, and supplies, after start of the switching control IC20, a power source voltage lower than the first set voltage but equal to or higher than the second set voltage.SELECTED DRAWING: Figure 1 |
