Method and apparatus for conditional response to a fault condition in a switching power supply

• US 20070008749A1
• Filed: 07/07/2005
• Published: 01/11/2007
• Est. Priority Date: 07/07/2005
• Status: Active Grant

• Current Assignee: Power Integrations Incorporated
• Original Assignee: Power Integrations Incorporated
• Inventors: Wong, Kent, Djenguerian, Alex, Baurle, Stefan
• Granted Patent: US 7,245,510 B2
• Time in Patent Office: Days
• US Class Current: 363/21.120
• CPC Class Codes: H02M 1/32 Means for protecting converters other than automatic disconnection
• 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 regulate an output of a power converter. One example power converter includes an energy transfer element coupled between an input and an output of the power converter. A switch included in the power converter is coupled to the input of the energy transfer element. The power converter also includes a controller circuit coupled to the switch. The controller circuit is also coupled to receive a feedback signal representative of the output of the power converter and coupled to receive a signal representative of the power converter input voltage. The controller circuit is coupled to control switching of the switch to provide a regulated output parameter at the output of the power converter in response to the feedback signal. The controller circuit is coupled to latch the power converter into an off state in response to a detection of a loss of regulation of a power converter output parameter if the power converter input voltage is above a threshold level. The controller circuit is also unresponsive to the signal representative of the power converter input voltage while the power converter output parameter is in regulation.

Claims

1. A power converter, comprising:

an energy transfer element coupled between an input and an output of the power converter;

a switch coupled to the input of the energy transfer element; and

a controller circuit coupled to the switch and coupled to receive a feedback signal representative of the output of the power converter and coupled to receive a signal representative of the power converter input voltage, the controller circuit to control switching of the switch to provide a regulated output parameter at the output of the power converter in response to the feedback signal, the controller circuit coupled to latch the power converter into an off state in response to a detection of a loss of regulation of a power converter output parameter if the power converter input voltage is above a threshold level, the controller circuit to be unresponsive to the signal representative of the power converter input voltage while the power converter output parameter is in regulation.

2. The power converter of claim 1 wherein the regulated output parameter comprises a voltage at the output of the power converter.

3. The power converter of claim 1 wherein the regulated output parameter comprises a current at the output of the power converter.

4. The power converter of claim 1 wherein the regulated output parameter comprises a combination of a voltage and a current at the output of the power converter.

5. The power converter of claim 1 further comprising an oscillator coupled to a latch to generate a drive signal to control the switching of the switch.

6. The power converter of claim 5 wherein the latch is coupled to be reset when the voltage at the input of the power converter falls below a restart threshold level.

7. The power converter of claim 5 wherein the power converter is coupled to restart when the signal representative of the input of the power converter rises above a startup threshold level after the latch has been reset.

8. The power converter of claim 7 wherein the restart and startup threshold levels are substantially equal.

9. The power converter of claim 1 wherein the loss of regulation of the power converter output parameter is detected by a loss of the feedback signal received by the controller circuit.

10. The power converter of claim 1 wherein the loss of regulation of the power converter output parameter is detected in response to the voltage at the output of the power converter exceeding an over voltage threshold.

11. The power converter of claim 10 wherein the voltage at the output of the power converter exceeding the over-voltage threshold is detected directly at the output of the power converter.

12. The power converter of claim 10 wherein the energy transfer element further comprises a bias winding to generate an output signal representative of a voltage at the output of the power converter, wherein the voltage at the output of the power converter exceeding an over voltage threshold is detected by sensing the output signal generated by the bias winding.

13. The power converter of claim 1 wherein the energy transfer element further comprises a bias winding to generate an output signal representative of a voltage at the output of the power converter, wherein the loss of regulation of the power converter output parameter is detected by sensing the output signal generated by the bias winding.

14. A power converter, comprising:

an energy transfer element coupled between an input and an output of the power converter;

a switch coupled to the input of the energy transfer element; and

a controller circuit coupled to the switch to control switching of the switch to regulate power delivered to a load to be coupled to the output of the power converter, the controller circuit coupled to receive a plurality of inputs some of which are adapted to detect a plurality of fault conditions in the power converter, wherein one of the plurality of inputs includes a signal representative of the power converter input voltage, the controller circuit coupled to latch the power converter into an off state in response to a detection of a fault condition in the power converter if the power converter input voltage is above a first threshold level, the controller circuit to be unresponsive to the signal representative of the power converter input voltage while the controller is regulating power delivered to the load.

15. The power converter of claim 14 wherein the power converter is coupled to be restarted when the power converter input voltage falls below a second threshold value and subsequently rises above the first threshold value.

16. The power converter of claim 15 wherein the first and second threshold values are substantially equal.

17. The power converter of claim 14 wherein the plurality of inputs includes a signal indicating a loss of regulation of an output parameter of the power converter.

18. The power converter of claim 14 wherein the plurality of inputs includes a signal representative of a temperature of a component within the power converter.