Compensation for parameter variations in a feedback circuit

• US 20060055382A1
• Filed: 09/13/2004
• Published: 03/16/2006
• Est. Priority Date: 09/13/2004
• Status: Active Grant

• Current Assignee: Power Integrations Incorporated
• Original Assignee: Power Integrations Incorporated
• Inventors: Odell, Arthur B., Cuadra, Jason E., Polivka, William Michael
• Granted Patent: US 7,535,735 B2
• Time in Patent Office: Days
• US Class Current: 323/280
• CPC Class Codes: H02M 1/0025 Arrangements for modifying reference values, feedback values or error values in the control loop of a converter
• CPC Class Codes: H02M 1/32 Means for protecting converters other than automatic disconnection
• CPC Class Codes: H02M 3/33523 with galvanic isolation between input and output of both the power stage and the feedback loop
• CPC Class Codes: Y10S 323/902 Optical coupling to semiconductor
• CPC Class Codes: Y10S 323/907 Temperature compensation of semiconductor

Abstract

Techniques to compensate for parameter variations in a feedback circuit are disclosed. In one embodiment, a regulator circuit includes an energy source coupled to output a generated current in response to a control current. A feedback resistor is coupled to an output of the regulator circuit. The feedback resistor is coupled to conduct a feedback current responsive to the output of the regulator circuit. A current amplifier is coupled to the feedback resistor to generate the control current in response to the feedback current. A compensation network is coupled to the current amplifier to adjust the control current in response to an extrinsic parameter of the regulator circuit. The compensation network includes a transistor and first, second and third resistors. The first resistor is coupled between the feedback resistor and a collector of the transistor. The second resistor coupled between the collector and the base of the transistor. The third resistor coupled between the base and an emitter of the transistor.

Claims

1. A regulator circuit, comprising:

an energy source coupled to output a generated current in response to a control current;

a feedback resistor coupled to an output of the regulator circuit, the feedback resistor to conduct a feedback current responsive to the output of the regulator circuit;

a current amplifier coupled to the feedback resistor to generate the control current in response to the feedback current; and

a compensation network coupled to an input of the current amplifier to adjust the control current in response to an extrinsic parameter of the regulator circuit, the compensation network including a transistor and first, second and third resistors, the first resistor coupled between the feedback resistor and a collector of the transistor, the second resistor coupled between the collector and the base of the transistor, and the third resistor coupled between the base and an emitter of the transistor.

2. The regulator circuit of claim 1 wherein the current amplifier includes an optocoupler having a photodiode and a phototransistor, wherein the photodiode is coupled to receive the feedback current and the phototransistor coupled to generate the control current.

3. The regulator circuit of claim 2 wherein a reference voltage of the regulator circuit comprises a voltage across the photodiode of the optocoupler.

4. The regulator circuit of claim 3 wherein the reference voltage is a first reference voltage value in response to a first extrinsic parameter value and wherein the reference voltage is a second reference voltage value in response to a second extrinsic parameter.

5. The regulator circuit of claim 4 wherein the feedback current is responsive to an output voltage of the regulator circuit and to the reference voltage.

6. The regulator circuit of claim 5 wherein the output voltage is substantially the same under the first and second extrinsic parameter values.

7. The regulator circuit of claim 1 wherein the extrinsic parameter of the regulator circuit includes at least one of temperature, ionizing radiation, and aging of the regulator circuit.

8. The regulator circuit of claim 1 wherein the energy source comprises a switched mode power supply controller integrated circuit coupled to an energy transfer element, the switched mode power supply controller integrated circuit coupled to receive the control current from the current amplifier, the energy transfer element coupled to output the generated current.

9. A regulator circuit, comprising:

an energy source coupled to output a generated current in response to a control current;

a feedback resistor coupled to an output of the regulator circuit, the feedback resistor to conduct a feedback current responsive to the output of the regulator circuit;

a current amplifier having an input terminal and an output terminal, the input terminal of the current amplifier coupled to the feedback resistor, wherein the control current is responsive to the feedback current and is derived from the output terminal of the current amplifier; and

a compensation network coupled to the output terminal of the current amplifier to adjust the control current in response to an extrinsic parameter of the regulator circuit.

10. The regulator of claim 9 wherein the compensation network comprises a transistor and first, second and third resistors, the first resistor coupled between the feedback resistor and a collector of the transistor, the second resistor coupled between the collector and the base of the transistor, and the third resistor coupled between the base and an emitter of the transistor.

11. The regulator of claim 9 wherein the compensation network comprises a thermistor.

12. The regulator circuit of claim 9 wherein the extrinsic parameter of the regulator circuit includes at least one of temperature, ionizing radiation, and aging of the regulator circuit.

13. The regulator circuit of claim 9 wherein the current amplifier includes an optocoupler having a photodiode and a phototransistor, wherein the photodiode is coupled to receive the feedback current and the phototransistor coupled to generate a current from which the control current is derived.

14. The regulator circuit of claim 13 wherein a reference voltage of the regulator circuit comprises a voltage across the photodiode of the optocoupler.

15. The regulator circuit of claim 14 wherein the reference voltage is a first reference voltage value in response to a first extrinsic parameter value and wherein the reference voltage is a second reference voltage value in response to a second extrinsic parameter.

16. The regulator circuit of claim 14 wherein the feedback current is responsive to an output voltage of the regulator circuit and to the reference voltage.

17. The regulator circuit of claim 16 wherein the output voltage is substantially the same under the first and second extrinsic parameter values.

18. The regulator circuit of claim 9 wherein the energy source comprises a switched mode power supply controller integrated circuit coupled to an energy transfer element, the switched mode power supply controller integrated circuit coupled to receive the control current derived from the current amplifier, the energy transfer element coupled to output the generated current.

19. A regulator circuit, comprising:

an energy source coupled to output a generated current in response to a control current;

a feedback resistor coupled to an output of the regulator circuit, the feedback resistor to conduct a feedback current responsive to the output of the integrated circuit;

an optocoupler including a photodiode and a phototransistor, the photodiode coupled to the feedback resistor to receive the feedback current, the phototransistor to generate a current in response to the feedback current, wherein the control current is responsive to the feedback current and is derived from the current generated by the phototransistor; and

a compensation network directly coupled between an anode and a cathode of the phototransistor of the optocoupler to adjust the control current in response to an extrinsic parameter of the regulator circuit.

20. The regulator circuit of claim 19 wherein a reference voltage of the regulator circuit comprises a voltage across the photodiode of the optocoupler.

21. The regulator circuit of claim 20 wherein the reference voltage is a first reference voltage value in response to a first extrinsic parameter value and wherein the reference voltage is a second reference voltage value in response to a second extrinsic parameter.

22. The regulator circuit of claim 21 wherein the feedback current is responsive to an output voltage of the regulator circuit and to the reference voltage.

23. The regulator circuit of claim 22 wherein the output voltage is substantially the same under the first and second extrinsic parameter values.

24. The regulator circuit of claim 19 wherein the compensation network comprises a transistor and first, second and third resistors, the first resistor coupled between the feedback resistor and a collector of the transistor, the second resistor coupled between the collector and the base of the transistor, and the third resistor coupled between the base and an emitter of the transistor.

25. The regulator circuit of claim 19 wherein the extrinsic parameter of the regulator circuit includes at least one of temperature, ionizing radiation, and aging of the regulator circuit.

26. The regulator circuit of claim 19 wherein the energy source comprises a switched mode power supply controller integrated circuit coupled to an energy transfer element, the switched mode power supply controller integrated circuit coupled to receive the control current from the current amplifier, the energy transfer element coupled to output the generated current.

27. The regulator circuit of claim 26 wherein the energy transfer element comprises a transformer having an input winding and an output winding, the input winding coupled to the switched mode power supply controller integrated circuit and the output winding coupled to output the generated current.