Method for driving a switch in a power factor correction circuit and drive circuit

A drive circuit for generating a drive signal for a switch controlling the current consumption of an inductive energy storage element in a switching converter, the drive circuit comprising:

• a first input operable to receive a control signal controlling a power consumption;
• a second input operable to receive a first storage state signal indicating a storage state of the inductive energy storage element;
• an output operable to provide the drive signal;
• a capacitive energy storage element;
• a charging circuit connected to the capacitive energy storage element, wherein the charging circuit provides a charging current dependent on the control signal according to a second storage state signal dependent on the first storage state signal;
• a discharging circuit connected to the capacitive energy storage element, wherein the discharging circuit provides a discharging current dependent on the control signal;
• a first comparator arrangement connected to the energy storage element, wherein the first comparator arrangement compares a voltage across the energy storage element with a first reference value;
• a second comparator arrangement connected to the energy storage element, wherein the second comparator arrangement compares the voltage across the energy storage element with a second reference value;
• and
• a signal generating circuit operable to generate a switch-on level of the drive signal depending on an output signal of the first comparator arrangement and operable to generate a switch-off level of the drive signal depending on an output signal of the second comparator arrangement.

A method for providing a drive signal for a switch operable to control the current consumption of an inductive energy storage element in a power factor correction circuit, the power factor correction circuit comprising a rectifier arrangement coupled to the inductive energy storage element and output terminals operable to provide an output voltage, and wherein a control signal is operable to control power consumption, the method comprising:

• generating a switch-on level of the drive signal for a switch-on duration dependent on the control signal, and generating a switch-off level of the drive signal after the switch-on duration has elapsed;
• detecting a predetermined storage state of the inductive energy storage element after the switch-on duration has elapsed;
• renewed generation the switch-on level of the drive signal upon detection of the predetermined storage state if the control signal indicates a power consumption above a predetermined first threshold;
• and
• waiting until the end of a waiting duration following the detection of the predetermined storage state before the renewed generation of the switch-on level if the control signal indicates a power consumption below the predetermined first threshold, wherein the waiting duration is substantially proportional to the time duration between the beginning of the switch-on level and the detection of the predetermined storage state and is dependent on the control signal.