Control circuit responsive to an impedance

• US 7,576,528 B2
• Filed: 10/04/2006
• Issued: 08/18/2009
• Est. Priority Date: 10/04/2006
• Status: Active Grant

• Current Assignee: Power Integrations Incorporated
• Original Assignee: Power Integrations Incorporated
• Inventors: Matthews, David Michael Hugh, Wang, Zhao-Jun, Baurle, Stefan
• Primary Examiner(s): Riley; Shawn
• Application Number:
  US11/543,506
• Publication Number:
  US 20080084712A1
• Time in Patent Office: 1,049 Days
• Field of Search: 323/284, 361/91.2, 361/91.3, 363/123
• US Class Current: 323/284
• 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 power supply controller measuring impedance includes a sense circuit coupled to a sense terminal. A regulation circuit is coupled to the sense circuit and is also coupled to regulate the sense terminal to a first voltage level when a current flowing through the sense terminal is less than a first threshold current level. The regulation circuit is further coupled to regulate the sense terminal to a second voltage level when the current flowing through the sense terminal reaches the first threshold current level. A response circuit is coupled to the sense circuit and is responsive to the current flowing through the sense terminal when the sense terminal is regulated at the second voltage level.

Claims

1. A power supply controller, comprising:

a sense circuit coupled to a sense terminal;

a regulation circuit responsive to the sense circuit and coupled to regulate the sense terminal to a first voltage level when a current flowing through the sense terminal is less than a first threshold current level, the regulation circuit further coupled to regulate the sense terminal to a second voltage level when the current flowing through the sense terminal reaches the first threshold current level; and

a response circuit coupled to the sense circuit and responsive to the current flowing through the sense terminal when the sense terminal is regulated at the second voltage level.

2. The power supply controller of claim 1 wherein the sense terminal is regulated to the second voltage level a delay period after the current flowing through the sense terminal reaches the first threshold current level.

3. The power supply controller of claim 1 wherein the second voltage level is less than the first voltage level.

4. The power supply controller of claim 1 wherein the second voltage level is greater than the first voltage level.

5. The power supply controller of claim 1 wherein the second voltage level is substantially equal to the first voltage level.

6. The power supply controller of claim 5 wherein the sense circuit is coupled to sense the current flowing through the sense terminal a measurement delay period after a magnitude of the current flowing through the sense terminal reaches the first threshold current level.

7. The power supply controller of claim 1 wherein the response circuit is coupled to latch off the power supply controller until the power supply controller is reset.

8. The power supply controller of claim 1 wherein the response circuit is coupled to auto restart the power supply controller in response to the sense circuit.

9. The power supply controller of claim 1 wherein the response circuit is coupled to latch off the power supply controller if the current flowing through the sense terminal is greater than a second threshold current level when the sense terminal is regulated at the second voltage level.

10. The power supply controller of claim 1 wherein the response circuit is coupled to auto restart the power supply controller if the current flowing through the sense terminal is less than a second threshold current level when the sense terminal is regulated at the second voltage level.

11. A power supply controller, comprising:

a sense circuit coupled to a sense terminal;

a regulation circuit responsive to the sense circuit and coupled to regulate a current flowing through the sense terminal to a first current value when a voltage at the sense terminal is less than a first threshold voltage level, the regulation circuit further coupled to regulate the current flowing through the sense terminal to a second current value when the voltage at the sense terminal reaches the first threshold voltage level; and

a response circuit coupled to the sense circuit and responsive to the voltage at the sense terminal when the current flowing through the sense terminal is regulated at the second current level.

12. The power supply controller of claim 11 wherein the sense terminal is regulated to the second current value a delay period after the voltage at the sense terminal reaches the first threshold voltage level.

13. The power supply controller of claim 11 wherein the second current level is less than the first current level.

14. The power supply controller of claim 11 wherein the second current level is greater than the first current level.

15. The power supply controller of claim 11 wherein the second current level is substantially equal to the first current level.

16. The power supply controller of claim 15 wherein the sense circuit is coupled to sense the voltage at the sense terminal a measurement delay period after the voltage at the sense terminal reaches the first threshold voltage level.

17. The power supply controller of claim 11 wherein the response circuit is coupled to latch off the power supply controller until the power controller is reset.

18. The power supply controller of claim 11 wherein the response circuit is coupled to auto restart the power supply controller in response to sense circuit.

19. The power supply controller of claim 11 wherein the response circuit is coupled to latch off the power supply controller if the voltage at the sense terminal is greater than a second threshold voltage level when the sense terminal is regulated at the second current level.

20. The power supply controller of claim 11 wherein the response circuit is coupled to auto restart the power supply controller if the voltage at the sense terminal is less than a second threshold voltage level when the sense terminal is regulated at the second current level.

21. A power supply controller, comprising:

a sense circuit coupled to a sense terminal;

a timing circuit coupled to measure a period of time taken for a current flowing through the sense terminal to change from a first threshold current level to a second threshold current level once the first current threshold level is reached; and

a response circuit coupled to the sense circuit and responsive to the period of time taken for the current flowing through the sense terminal to change from the first threshold current level to the second threshold current level.

22. The power supply controller of claim 21 wherein the response circuit is coupled to latch off the power supply controller until the power supply controller is reset.

23. The power supply controller of claim 21 wherein the response circuit is coupled to auto restart the power supply controller in response to sense circuit.

24. The power supply controller of claim 21 wherein the response circuit is coupled to latch off the power supply controller if the period of time taken for the current flowing through the sense terminal to change from a first threshold current level to a second threshold current level is less than a threshold time period.

25. The power supply controller of claim 21 wherein the response circuit is coupled to auto restart the power supply controller if the period of time taken for the current flowing through the sense terminal to change from a first threshold current level to a second threshold current level is greater than a threshold time period.

26. A method for controlling a power supply, comprising:

sensing a sense terminal of a power supply controller;

regulating the sense terminal, responsive to the sensing of the sense terminal, to a first voltage level when a current flowing through the sense terminal is less than a first threshold current level;

measuring an impedance coupled to the sense terminal when the current flowing through the sense terminal reaches the first threshold current level; and

generating a power supply controller response in response to the impedance coupled to the sense terminal.

27. The method of claim 26 wherein measuring the impedance coupled to the sense terminal comprises detecting the current flowing through the sense terminal at a plurality of voltage levels on the sense terminal.

28. A method for controlling a power supply, comprising:

sensing a sense terminal of a power supply controller;

regulating a current flowing through the sense terminal, responsive to the sensing of the sense terminal, to a first current value when a voltage at the sense terminal is less than a first threshold voltage level;

measuring an impedance coupled to the sense terminal when the voltage at the sense terminal reaches the first threshold voltage level; and

generating a power supply controller response in response to the impedance coupled to the sense terminal.

29. The method of claim 28 wherein measuring the impedance coupled to the sense terminal comprises detecting the voltage level at the sense terminal at a plurality of currents flowing through the sense terminal.

30. A method for controlling a power supply, comprising:

sensing a sense terminal of a power supply controller;

measuring a period of time taken for a current flowing through the sense terminal to change from a first threshold current level to a second threshold current level once the first current threshold level is reached;

generating a power supply controller response in response to the period of time taken for the current flowing through the sense terminal to change from the first threshold current level to the second threshold current level.