METHOD AND APPARATUS PROVIDING PROTECTION FOR POWER CONVERTER

• US 20080025054A1
• Filed: 07/31/2006
• Published: 01/31/2008
• Est. Priority Date: 07/31/2006
• Status: Active Grant

• Current Assignee: Semiconductor Components Industries LLC (ON Semiconductor Corporation)
• Original Assignee: System General Corporation (ON Semiconductor Corporation)
• Inventors: Yang, Ta-yung, Lin, Chien-Yuan, Chen, Tso-Min
• Granted Patent: US 7,602,160 B2
• Time in Patent Office: Days
• US Class Current: 363/56.01
• 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

The invention presents a surge output protection for a control circuit of power converter. It comprises an input circuit for generating a threshold signal. A first comparator is coupled to receive a signal representative the current through a power switch. The first comparator further generates a control signal in response to the signal and the threshold signal. A timer circuit is utilized to generate a time-out signal in response to the control signal. The time-out signal is coupled to turn off the power switch.

Claims

1. A switching control circuit for a power converter, comprising:

an input circuit coupled to receive a threshold signal at an input terminal;

a first comparator coupled to receive a signal representative of the current of a power switch, the first comparator to generate a control signal in response to the signal and the threshold signal;

a second comparator coupled to receive the signal to limit the current of the power switch;

a timer circuit coupled to generate a timing signal at a timer terminal in response to the control signal, the timer circuit to generate a time-out signal in response to the timing signal;

wherein the time-out signal is used to turn off the power switch.

2. The switching control circuit as claimed in claim 1, wherein the second comparator is coupled to compare the signal representative of the current through the power switch with a current-limit threshold signal such that the power switch is turned off in response to the output of the second comparator when the current limit set by the current-limit threshold signal is exceeded.

3. The switching control circuit as claimed in claim 1, wherein the threshold signal is lower than the current-limit threshold signal.

4. The switching control circuit as claimed in claim 1, wherein the switching control circuit is a pulse width modulation circuit that generates a switching signal coupled to be received by a power switch to regulate the output of the power converter.

5. The switching control circuit as claimed in claim 4, wherein the switching control circuit is used to generate the switching signal controlled in response to the output of the first comparator and the output of the second comparator such that the switching signal is coupled to protect the power switch.

6. A control circuit for a power converter, comprising:

an input circuit generating a threshold signal;

a first comparator coupled to receive a signal representative of the current through a power switch, the first comparator to generate a control signal in response to the signal and the threshold signal;

a timer circuit coupled to generate a time-out signal in response to the control signal;

wherein the time-out signal is used to turn off the power switch.

7. The control circuit as claimed in claim 6, further comprising a second comparator coupled to compare the signal representative of the current through the power switch with a current-limit threshold signal such that the power switch is turned off in response to the output of the second comparator when the current limit set by the current-limit threshold signal is exceeded.

8. The control circuit as claimed in claim 6, wherein the threshold signal is lower than the current-limit threshold signal.

9. The control circuit as claimed in claim 6, wherein the control circuit is a pulse width modulation circuit that generates a switching signal coupled to be received by power switch to regulate an output of the power converter.

10. The control circuit as claimed in claim 9, wherein the control circuit is to generate the switching signal controlled in response to the output of the first comparator and the output of the second comparator such that the switching signal is coupled to protect the power switch.

11. A switching circuit for power converter, comprising:

an oscillation circuit generating a switching signal for regulating the output of the power converter;

a first circuit generating a threshold signal;

a first comparator coupled to receive a signal representative of the current through a power switch, the first comparator to generate a control signal in response to the signal and the threshold signal;

wherein the frequency of the switching signal is increased in response to the enable of the control signal.

12. The switching circuit as claimed in claim 11, further comprising a second comparator coupled to compare the signal representative of a current through the power switch with a current-limit threshold signal such that the power switch is turned off in response to an output of the second comparator when the current limit set by the current-limit threshold signal is exceeded.

13. The switching circuit as claimed in claim 11, wherein the threshold signal is lower than the current-limit threshold signal.

14. The switching circuit as claimed in claim 11, wherein the switching circuit is a pulse width modulation circuit that generates the switching signal coupled to be received by the power switch to regulate the output of the power converter.

15. The switching circuit as claimed in claim 14, wherein the switching circuit is used to generate the switching signal controlled in response to the output of the first comparator and the output of the second comparator such that the switching signal is coupled to protect the power switch.