Optimal control of wide conversion ratio switching converters

A frequency controller comprising:

• a current detector coupled between a first transconductor and a second transconductor;
• a first integrator coupled to the first transconductor;
• a second integrator coupled to the second transconductor;
• a comparison device coupled to the first and second integrators;
• a charge pump coupled to the comparison device;
• and
• a voltage-to-frequency converter coupled to the charge pump;
• wherein the period output by the frequency controller is adjusted in conformance with a detected current.

A power supply circuit comprising:

• a rectifier coupled to an input of the power supply circuit for producing a rectified power signal from an AC input voltage;
• a plurality of cascaded converter stages, a first of the cascade having an input coupled to an output of the rectifier, the converter stages each comprising at least one energy storage element, for providing conversion of the rectified power signal to a DC output, via charging and discharging of the energy storage elements;
• a switching device for switching the plurality of converter stages whereby an output of the power supply is maintained substantially constant as the rectified power signal varies in instantaneous amplitude;
• and
• a switch state controller coupled to the switching device so the on-time is varied inversely with an instantaneous rectified AC amplitude and the period is set in conformity with a measured power supply output characteristic.

A method for converting an AC power signal to a DC power output comprising the steps of:

• rectifying the AC power signal to produce a rectified power signal;
• switching the unfiltered rectified power signal with a pulse train of controlled period and conduction pulse time;
• adjusting a conduction time in conformity with the voltage magnitude of one of the rectified AC power signal or an internal node;
• and
• adjusting a period in conformity with a signal proportional to a characteristic of the DC power output.

A power factor correction device comprising:

• an integrated circuit containing a switch state controller wherein the switch state controller is used for producing a pulse train, a frequency of the pulse train controlled by a feedback signal coupled from an output characteristic of the power supply circuit, the switch state controller coupled to one of an input or internal node of a power supply circuit for controlling the on time of each pulse in the pulse train;
• a resistor divider coupled to a rectified AC voltage source and to a VON pin;
• and
• a filter coupled to the resistor divider to produce a filtered DC voltage at VON proportional to the RMS value of the rectified AC input voltage.

An overvoltage protection circuit comprising:

• an integrated circuit containing a switch state controller wherein the switch state controller is used for producing a frequency modulated pulse train, a frequency of the pulse train controlled by a feedback signal coupled from an output characteristic of the power supply circuit, the switch state controller coupled to one of an input or internal node of a power supply circuit for controlling the on time of each pulse in the pulse train;
• a clamp connecting one of an integrated circuit feedback transconductor terminals to a power converter output voltage;
• and
• a clamp from an output voltage to ground/common.