One cycle controlled power factor correction circuit

A control circuit for controlling a Switch-Mode Power Supply (SMPS), the control circuit comprising:

• a current conduction duration determining circuit to produce a duration signal according to a duration of a current of the SMPS;
• an integrator circuit to produce an integrator output corresponding to an integral over time of a magnitude of the current of the SMPS;
• a feedback circuit to produce a comparison voltage according to an output voltage of the SMPS;
• a sawtooth generator circuit to produce a sawtooth signal according to the comparison voltage and the duration signal;
• and
• a gate control circuit to generate a gate signal for controlling a power switch of the SMPS according to a comparison of the sawtooth signal and the integrator output.

A method for controlling a Switched Mode Power Supply (SMPS) circuit, the method comprising:

• producing, by an integrator circuit, an integrator output corresponding to an integral over the duration of a measurement cycle of a value of a current sense signal, the current sense signal indicating a current of the SMPS circuit;
• producing, by a duration determining circuit, a duration signal corresponding to a duration of the current of the SMPS circuit;
• producing, by an oscillator circuit according to the duration signal, a sawtooth signal having a plurality of values at a plurality of times within a time period of the measurement cycle, respectively, each value of the sawtooth signal corresponding to a target integrated current value for the respective time, the target integrated current value corresponding to a target average current for the measurement cycle;
• determining, by a comparison circuit during the time period of the measurement cycle, a reset signal indicating whether the value of the integrator output is greater than the sawtooth signal;
• and
• producing, using the reset signal, a gate signal to control the current of the SMPS circuit.