METHOD AND APPARATUS TO CONTROL OUTPUT POWER FROM A SWITCHING POWER SUPPLY

• US 20080007240A1
• Filed: 09/17/2007
• Published: 01/10/2008
• Est. Priority Date: 01/18/2005
• Status: Active Grant

• Current Assignee: Power Integrations Incorporated
• Original Assignee: Power Integrations Incorporated
• Inventors: Hawley, Stephen
• Granted Patent: US 7,554,826 B2
• Time in Patent Office: Days
• US Class Current: 323/284
• CPC Class Codes: H02M 1/32 Means for protecting converters other than automatic disconnection
• CPC Class Codes: H02M 3/156 with automatic control of output voltage or current, e.g. switching regulators
• CPC Class Codes: H02M 3/33507 with automatic control of the output voltage or current, e.g. flyback converters H02M3/33561, H02M3/33569 take precedence

Abstract

Techniques are disclosed to control output power from a switching power supply. A sample power converter controller circuit includes a control circuit coupled to be coupled to a switch. The control circuit includes a current sense circuit to be coupled to a primary winding of an energy transfer element coupled to the switch. The control circuit also includes a measurement circuit to be coupled to a secondary winding of the energy transfer element. A feedback circuit is also included and is coupled to the control circuit and coupled to receive a feedback-signal derived from an output of a power converter. The feedback circuit is coupled to output a signal to the measurement circuit. An output of the measurement circuit and an output of the current sense circuit are coupled to control a switching of the switch to regulate a combination of an output voltage and an output current of the power converter. A combination of the output voltage and the output current corresponds to at least one of a regulated output region and an unregulated output region. At least one of the unregulated output regions is a self protection auto-restart region. Within at least one unregulated output region the power converter controller circuit provides continuous output power at a substantially maximum output power of the power converter. Each output region corresponds to a magnitude and duration of the feedback signal.

Claims

1. A power converter controller circuit, comprising:

a control circuit coupled to be coupled to a switch, the control circuit including a current sense circuit to be coupled to a primary winding of an energy transfer element coupled to the switch, the control circuit further including a measurement circuit to be coupled to a secondary winding of the energy transfer element; and

a feedback circuit coupled to the control circuit and coupled to receive a feedback-signal derived from an output of a power converter and to output a signal to the measurement circuit.

wherein an output of the measurement circuit and an output of the current sense circuit are coupled to control a switching of the switch to regulate a combination of an output voltage and an output current of the power converter, wherein a combination of the output voltage and the output current correspond to at least one of a regulated output region and an unregulated output region, wherein at least one unregulated output region is a self protection auto-restart region, wherein within at least one unregulated output region the power converter controller circuit provides continuous output power at a substantially maximum output power of the power converter, and wherein each output region corresponds to a magnitude and duration of the feedback signal.

2. The power converter controller circuit of claim 1 wherein the power converter controller circuit is included in a battery charger.

3. The power converter controller circuit of claim 1 wherein the control circuit includes an integrated circuit.

4. The switching regulator of claim 1 wherein the control circuit includes discrete electrical components.

5. A method for operating a power converter, comprising:

measuring a feedback signal received from a secondary winding of an energy transfer element of the power converter;

sensing a current received from a primary winding of the energy transfer element, an output power of the power converter controlled in response to the feedback signal and the sensed current;

operating the power converter in an unregulated auto-restart mode if the feedback signal is less than a first threshold; and

operating the power supply in a regulated mode if the feedback signal is between the first threshold and a second threshold while greater than a third threshold.

6. The method of claim 5 further comprising operating the power converter in an unregulated inhibited switching mode if the feedback signal is greater than the second threshold.

7. The method of claim 6 further comprising operating the power converter in an unregulated maximum power mode if the feedback signal is between the first threshold and the third threshold.

8. The method of claim 7 wherein the first threshold less than the third threshold.

9. The method of claim 8 wherein the third threshold is less than or equal to the second threshold.

10. The method of claim 7 wherein the output power of the power converter is nonresponsive to the feedback signal when the power converter is operating in any one of the unregulated auto-restart mode, the unregulated inhibited switching mode or the unregulated maximum power mode.