A novel power supply and detection circuit for high voltage synchronous rectifier (SR) is proposed in this digest. The circuit is improved on the basis of the traditional transistor series voltage regulator power supply circuit, and realizes the isolation and chopping of the detected high source-drain voltage without sacrificing the detection accuracy. Meanwhile, this circuit has low cost and high versatility, and can be applied to existing commercial SR control ICs, and greatly reduces the input sensing voltage of the SR controller. Finally, the power supply and detection circuit is verified on a 500kHz flyback converter with ON Semiconductor's NCP4306 SR control IC.
