Patent ID: 7333353

Claim:
An isolating type self-oscillating flyback converter, comprising a coupled transformer, a FET, an oscillating transistor and an optical-electro coupled isolating feedback unit, wherein the input terminal of said converter is connected to the source of said FET through a primary winding of said coupled transformer, said input terminal of said converter is connected to the collector of said oscillating transistor through a first resistor and a second resistor, said source of said FET is connected to said collector of said oscillating transistor, one branch of the drain of said FET is connected to the ground through a third resistor and another branch is connected to the base of said oscillating transistor through a parallel connection unit of a resistor and a capacitor, and said base of said oscillating transistor is connected to the output terminal of a secondary output winding of said coupled transformer through said electro-optical coupled isolating feedback unit; and there is a series connection joint between said first resistor and said second resistor connected to the ground through a speedup capacitor and a secondary winding of said coupled transformer; wherein a soft start means of said converter is connected between said input terminal of said converter and said series connection joint; and wherein said soft start means either comprises said first resistor, a fourth resistor and a capacitor, said fourth resistor is connected between said first resistor and said series connection joint in series, and one terminal of said capacitor is connected between said first resistor and said fourth resistor, while another terminal is connected to the ground, or comprises said first resistor and an inductance, and said first resistor and said inductance are connected between said input terminal of said converter and said series connection joint in series.