Patent ID: 8183844

Claim:
A switching power source, comprising: a switching power source controller including a soft start circuit; an output stage for outputting a negative voltage, the output stage including a coil, a switching device, driven by an output from the switching power source controller, for controlling a current flowing in the coil, and a diode having an anode connected to an output terminal and a cathode connected to a connection point between the switching device and the coil; a voltage dividing circuit for dividing a potential difference between a positive output voltage from the soft start circuit and a negative voltage fed back from the output terminal; and a soft start period adjustment circuit for outputting a positive voltage to adjust a soft start period to an input section of the soft start circuit immediately after a power source is turned on, wherein the soft start circuit outputs the positive voltage to set the soft start period and the voltage dividing circuit outputs the divided potential difference to an input section of the switching power source controller.