Onkyo Corporation

Koji Takatori

Sadatoshi Hisamoto

Joji Kasai

Tadashi Yamamoto

A switching power supply circuit of the present invention includes: a transformer including a main winding and an auxiliary winding, which are magnetically coupled together on a primary winding side; a switching element for intermittently supplying a direct-current voltage to the main winding; and a controller for turning ON/OFF the switching element using a voltage induced across the auxiliary winding by the intermittent supply of the direct-current voltage. The switching power supply circuit includes a startup circuit, the startup circuit including: a startup switch connected to the main winding; and a driving pulse generator for outputting a driving pulse to the startup switch for turning ON the startup switch.

Switching power supply circuit

A pulse-width modulation circuit converts an input signal into a pulse signal to be supplied to a switch amplifying circuit. The modulation circuit includes a comparison signal generator, an amplitude controller for modulating a comparison signal from the signal generator, and a comparator for comparing the modulated comparison signal and the input signal. The comparator outputs a signal whose level is inverted in accordance with the level of the input signal. The signal outputted from the comparator is supplied to the switch amplifying circuit.

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Okayama, Japan

Koji Takatori