Dimmable LED power supply with power factor control

A method of managing a power supply, the method comprising:

• sensing a current signal of a primary current of a transformer;
• determining a switching signal comprising comparing a prepared current signal based on the sensed current signal and a reference signal, wherein the reference signal represents a rectified alternating line voltage;
• controlling the primary current of the transformer based on the switching signal in a quasi-resonant mode of operation;
• conditioning the sensed current signal;
• and
• processing the sensed current signal, wherein processing the sensed current signal comprises applying to the sensed current signal an equation:
• Vs′=m Vsx +Vo,
• wherein Vs is the sensed current signal, Vs′ is the processed sensed current signal, m is a gain factor, Vo is an offset, and x is an exponent value.

A circuit comprising:

• an input node configured to receive a rectified alternating line voltage;
• a transformer having a primary winding and a secondary winding, wherein the primary winding is coupled to the input node, and wherein the primary winding has a current;
• a switch coupled to the primary winding, wherein the switch is configured to control the current of the primary winding based on a driver signal;
• a current sense unit coupled to the primary winding, wherein the current sense unit is configured to output a current sense signal proportional to the current of the primary winding;
• and
• a control unit coupled to the current sense unit and the input node, the control unit comprising
• a comparator having a first input, a second input, and an output, and
• a signal processing unit operatively coupled between the current sense unit and the first input of the comparator, wherein the control unit is configured to output the driver signal based on the current sense signal, and wherein the control unit is configured to drive the switch coupled to the primary winding such that a short-term average of the current of the primary winding follows a rectified line voltage waveform so as to provide a power factor correction.