| 摘要 |
A DC (direct current) converter includes a PWM (pulse width modulation) pulse generation unit outputting a PWM pulse signal whose duty ratio is controlled in accordance with an output voltage, a PFM (pulse frequency modulation) pulse generation unit outputting a PFM pulse signal whose pulse output interval is controlled in accordance with an output voltage, a selection circuit selecting and outputting any one of the PWM pulse signal and the PFM pulse signal in response to a selection signal, a drive circuit unit driving a load and generating an output voltage on the basis of a signal outputted from the selection circuit, and a switching control unit outputting the selection signal. When the selection signal is in a second state, the switching control unit detects a fact that the number of pulses of the PFM pulse signal in a measurement period increases to or above a set value of the maximum number of pulses, and switches the selection signal to a first state.
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