Patent ID: 7310244

Claim:
A switching regulator, comprising: a transformer, transferring the energy from a primary side of the transformer to a secondary side of the transformer, wherein the transformer includes a primary winding and an auxiliary winding, wherein the primary winding and the auxiliary winding are coupled to a positive supply rail and a negative supply rail respectively; a switch, connected in series with the primary winding and the auxiliary winding for switching the transformer; a control circuit, coupled to the switch and the auxiliary winding to generate a switching signal for switching the switch and regulating the output of the switching regulator; a supplied capacitor, connected to the control circuit to supply the power to the control circuit; and a diode, coupled from the negative supply rail to the supplied capacitor for charging the supplied capacitor; the control circuit further including: a voltage detection terminal, coupled to the auxiliary winding for detecting a voltage from the transformer; a current sense terminal, coupled to the switch for receiving a current signal; an output terminal, generating the switching signal to switch the transformer via the switch; a sample-hold circuit, coupled to the voltage detection terminal to detect the voltage from the transformer for generating a sample signal; an error amplifier, coupled to the sample-hold circuit, wherein the error amplifier receives a reference voltage and the sample signal for generating a feedback signal; a comparator, coupled to the error amplifier and the current sense terminal to receive the feedback signal and the current signal for generating a reset signal; an oscillator, generating a periodic pulse signal; and a flip-flop, coupled to the oscillator, the comparator and the output terminal for generating the switching signal, wherein the periodic pulse signal and the reset signal are used to start and turn off the switching signal respectively.