US 10,312,799 B1 · Offline converter with power factor correction at light loads and method therefor

Abstract

In one form, a power factor correction (PFC) controller, comprising includes a regulation circuit, a dead-time detection circuit, and a pulse width modulator. The regulation circuit provides a control voltage in response to a feedback voltage received at a feedback input terminal, wherein the feedback voltage is proportional to an output voltage. The dead-time detection circuit has an input coupled to a zero current detection input terminal, and an output for providing a dead-time signal. The pulse width modulator is responsive to the control voltage and the dead-time signal to provide a drive signal that controls conduction of a switch to improve a power factor of an offline converter, wherein the pulse width modulator modulates both an on-time and a switching period of the drive signal using the dead-time signal in a discontinuous conduction mode.

Claims26

Dependent claims

A power factor correction (PFC) controller, comprising:

a regulation circuit for providing a control voltage in response to a feedback voltage received at a feedback input terminal, wherein said feedback voltage is proportional to an output voltage;
a dead-time detection circuit having an input coupled to a zero current detection input terminal, and an output for providing a dead-time signal;
and
a pulse width modulator responsive to said control voltage and said dead-time signal to provide a drive signal that controls conduction of a switch to improve a power factor of an offline converter, wherein said pulse width modulator modulates both an on-time and a switching period of said drive signal using said dead-time signal in a discontinuous conduction mode without substantially changing dead time.

1 more element

An offline converter, comprising:

a rectifier for converting a sinusoidal input voltage into a rectified input voltage;
an inductive element having a first terminal for receiving said rectified input voltage, and a second terminal;
a diode having a first terminal coupled to said second terminal of said inductive element, and a second terminal for providing a bulk voltage for a load;
a bulk capacitor having a first terminal coupled to said second terminal of said diode, and a second terminal coupled to ground;
a switch having a first current electrode coupled to said second terminal of said inductive element, a control terminal, and a second current electrode;
and
a PFC controller coupled to said inductive element, said second terminal of said diode, and said control terminal of said switch, wherein said PFC controller modulates a conduction of said switch to make a current through said inductive element in phase with said rectified input voltage, wherein in a discontinuous conduction mode said PFC controller modulates both an on-time of said switch and a switching period of said switch according to a dead-time.

4 more elements

Dependencies are inferred from the claim text.

Offline converter with power factor correction at light loads and method therefor

Life of this patent

Offline converter with power factor correction at light loads and method therefor

Life of this patent

Abstract

Claims26