Step-up/step-down DC-DC converter and vehicle lighting appliance

摘要

A step-up/step-down DC-DC converter includes a control section to compare an output value from voltage decrease or increase sections and a preset target value. A computation circuit provides a voltage value resulting from subtracting a difference between the voltage value of the comparison result and a first preset voltage value from a first voltage value. A drive pulse generation section generates a drive pulse for turning on and off a voltage decrease switch and a voltage increase switch in response to the result of a comparison between the computation output voltage and a ramp wave. When the voltage value of the computation output voltage exists between the first voltage value and the second voltage value, the drive pulse generation section provides control to selectively switch the on and off operation of the voltage decrease switch and the on and off operation of the voltage increase switch.