Patent ID: 7889522
Filing Date: 2011-02-15
Classification: H02M

Abstract:
1. A flyback switching power supply, comprising: a transformer comprising a primary winding for receiving an input voltage, a secondary winding for generating an output voltage, and an auxiliary winding; a switch, electrically coupled to the primary winding in series, for controlling a current flowing through the primary winding; a switch control circuit comprising a frequency control port, the switch control circuit being working around an operation frequency for controlling the switch, the operation frequency being controlled by a frequency setting current flowing through the frequency control port; a power generation circuit, comprising a filter capacitor and a regular diode connected in series, the regular diode having an anode connected to the auxiliary winding, the filter capacitor having a first terminal coupled to ground and a second terminal coupled to the switch control circuit so as to generate a power voltage provided to the switch control circuit based on an induced current; and a regulation circuit, comprising a receiving terminal coupled to the auxiliary winding and the anode of the regular diode and an adjusting terminal coupled to the frequency control port, for adjusting the frequency setting current based on the induced current generated by the auxiliary winding.