Patent ID: 7675279

Claim:
A switching regulator for generating a predetermined stabilized voltage at an output terminal of said switching regulator by feeding back a portion or a whole portion of a voltage outputted from said output terminal to a load back to one of inputs of an error amplifier, applying a predetermined constant voltage to the other input of said error amplifier to generate a PWM pulse having a pulse width which is changed according to an output signal of said error amplifier and switching a D.C. power source according to the PWM pulse, comprising: a triangular wave generator circuit for generating a triangular wave signal; a PWM pulse generator circuit for generating the PWM pulse by comparing the voltage of the output signal of said error amplifier with a voltage of the triangular wave signal; a detection circuit for detecting a change of the PWM pulse from High level to Low level or vice versa; and a soft start circuit for generating a voltage signal which gradually increases stepwise or gradually reduces stepwise and a step voltage of the voltage signal is compared with the voltage of the triangular wave signal, a changing period of the step voltage of said soft start circuit being a predetermined period in an initial period after the power is supplied and an initial voltage of the voltage signal when the power is supplied being outside of a voltage amplitude range of the triangular wave signal, the changing period of the step voltage according to the detection signal of said detection circuit being switched to a period which is larger than the predetermined period and is suitable for a soft start.