STEP-UP/DOWN DC-DC CONVERTER AND SWITCHING CONTROL CIRCUIT

摘要

In order to reduce switching loss during the transmission period of switching between step-up and step-down and improve the power generating efficiency in a step-up/down DC-DC converter, a switching control circuit is provided with: an error amplification circuit (21) that outputs a voltage according to the output voltage of the DC-DC converter; an inverting amplifier circuit (22) that inverts the output of the error amplification circuit on the basis of a predetermined voltage; a waveform generation circuit (23) that generates a triangular waveform; a first voltage comparison circuit (25) into which the output of the error amplification circuit and the waveform generation circuit are inputted; a second voltage comparison circuit (26) into which the output of the inverting amplifier circuit and the waveform generating circuit are inputted; and a voltage generation circuit (24) which generates the inverting reference voltage which is supplied to the inverting amplifier circuit. The device is constituted in such a manner that the inverting reference voltage supplied to the inverting amplifier circuit does not have a lower potential than the highest potential of the triangular wave supplied to the voltage comparison circuit.