Abstract: Switching power supplies are employed in electronic equipment using batteries as the power source, for the purposes of operating such equipment with a smaller number of batteries and of extending battery life. A switching power supply can efficiently supply stable voltages even when the battery voltage is lower or higher than the load voltage. Two mutually inverted triangular waves are generated by two triangular-wave generator circuits. Signals proportional to the voltage level from either a primary switching circuit for stepping down the input voltage or a secondary switching circuit for stepping up the input voltage are compared against the two triangular waves and pulse signals are generated. Using these pulse signals, the primary and secondary switching circuits are controlled.