METHOD AND APPARATUS FOR A CONTROL CIRCUIT RESPONSIVE TO AN IMPEDANCE COUPLED TO A CONTROL CIRCUIT TERMINAL

• US 20120280666A1
• Filed: 07/19/2012
• Published: 11/08/2012
• Est. Priority Date: 10/04/2006
• Status: Active Grant

• Current Assignee: Power Integrations Incorporated
• Original Assignee: Power Integrations Incorporated
• Inventors: Wang, Zhao-Jun, Bäurle, Stefan, Matthews, David Michael Hugh
• Granted Patent: US 8,582,327 B2
• Time in Patent Office: Days
• US Class Current: 323/234
• 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
• CPC Class Codes: H02M 3/33523 with galvanic isolation between input and output of both the power stage and the feedback loop

Abstract

A method, in a power supply controller, of responding to an increase in current through a terminal of the power supply controller, is disclosed. The method includes regulating the terminal to a first voltage level and sensing a magnitude of a first current through the terminal while the controller is regulating the terminal to the first voltage level. The method also includes providing an initial response by the power supply controller in response to the magnitude of the first current exceeding a first threshold current level and then regulating the terminal to a second voltage level after the magnitude of the first current exceeds the first threshold current level. The magnitude of a second current through the terminal is sensed while the controller is regulating the terminal to the second voltage level and the controller determines a final response based on the magnitude of the second current.

Claims

1. A method, in a power supply controller, of responding to an increase in current through a terminal of the power supply controller, the method comprising:

regulating the terminal to a first voltage level;

sensing a magnitude of a first current through the terminal while the controller is regulating the terminal to the first voltage level;

providing an initial response by the power supply controller in response to the magnitude of the first current exceeding a first threshold current level;

regulating the terminal to a second voltage level after the magnitude of the first current exceeds the first threshold current level;

sensing a magnitude of a second current through the terminal while the controller is regulating the terminal to the second voltage level; and

determining a final response of the power supply controller in response to the magnitude of the second current.

2. The method of claim 1, wherein the terminal is to be coupled to an impedance of a power supply, and wherein the determining of the final response of the power supply controller in response to the magnitude of the second current includes determining whether the impedance is a resistive impedance.

3. The method of claim 2, wherein the final response is a first final response if the impedance is determined to be a resistive impedance and is a second final response if the impedance is determined to be a non-resistive impedance.

4. The method of claim 3, wherein the magnitude of the second current being below a second threshold current level indicates that the impedance is a resistive impedance and the magnitude of the second current being above the second threshold current level indicates that the impedance is a non-resistive impedance.

5. The method of claim 1, wherein power supply controller determines that the final response is a first final response if the impedance is determined to include a Zener diode and is a second final response if the impedance is determined to not include the Zener diode.

6. The method of claim 5, wherein the magnitude of the second current being above a second threshold current level indicates that the impedance includes a Zener diode and the magnitude of the second current being below the second threshold current level indicates that the impedance does not include the Zener diode.

7. The method of claim 1, wherein the initial response provided by the power supply controller includes ceasing operation of the power supply controller.

8. The method of claim 1, wherein the first voltage level is greater than the second voltage level.

9. The method of claim 1, wherein the power supply controller regulates the terminal to the second voltage level substantially immediately after the magnitude of the first current exceeds the first threshold current level.

10. The method of claim 1, wherein the power supply controller regulates the terminal to the second voltage level a delay period after the magnitude of the first current exceeds the first threshold current level to increase the power supply controller'"'"'s immunity to noise.