| 摘要 |
A DC-DC converter includes a control circuit which can change the target voltage of the reference voltage source. At the start-up of the DC-DC converter, the PWM control circuit controls so that the first switching element gradually increases the on-off ratio from a minimum on-off ratio; that the second switching element is placed in the OFF state, and that the target voltage is set higher than the normal operating voltage. When the start-up operation is completed, the PWM control circuit controls so that the second switching element starts to turn on and off, and that the target voltage is returned to the normal operating voltage.
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