High power factor primary regulated offline LED driver

A circuit, comprising:

• a transformer including a primary winding having a first terminal configured to receive a rectified DC signal derived from an AC signal, and having a second terminal;
• a comparison circuit having a first input, a second input and an output;
• a power transistor having a first conduction terminal coupled to the second terminal of the primary winding, and having a second conduction terminal coupled to the first input of the comparison circuit to provide a signal indicative of sensed current flowing through the power transistor, and further having a control terminal coupled to the output of the comparison circuit;
• a divider circuit configured to receive the rectified DC signal and generate a divided rectified DC signal that has a DC component and an AC component;
• and
• a DC blocking capacitor coupled between the divider circuit and the second input of the comparison circuit, said DC blocking capacitor functioning to block the DC component and apply the AC component to the second input of the comparison circuit,
• wherein said comparison circuit is configured to turn off the power transistor when the signal indicative of sensed current flowing through the power transistor reaches a variable reference modulated by the AC component.