Applications of halogen converter control IC

• US 7,521,878 B2
• Filed: 08/01/2007
• Issued: 04/21/2009
• Est. Priority Date: 04/08/2004
• Status: Active Grant

• Current Assignee: Infineon Technologies Americas Corp. (Infineon Technologies AG)
• Original Assignee: International Rectifier Corporation (Infineon Technologies AG)
• Inventors: Green, Peter
• Primary Examiner(s): Vu; David Hung
• Assistant Examiner(s): Le; Tung X
• Application Number:
  US11/832,302
• Publication Number:
  US 20080018268A1
• Time in Patent Office: 629 Days
• Field of Search: 315/209.R, 315224-226, 315/244, 315/246, 315/291, 315/292, 315/297, 315307-308, 315/316, 315/324
• US Class Current: 315/291
• CPC Class Codes: H02M 1/0012 Control circuits using digital or numerical techniques in DC/DC converters H02M3/157, H02M3/33515; in DC-AC converters H02M7/53873
• CPC Class Codes: H02M 5/458 using semiconductor devices only
• CPC Class Codes: H05B 39/045 with high-frequency bridge converters H05B39/048 takes precedence
• CPC Class Codes: H05B 47/18 via data-bus transmission
• CPC Class Codes: Y02B 20/00 Energy efficient lighting technologies, e.g. halogen lamps or gas discharge lamps

Abstract

The functionality of electronic convertors for low voltage filament lamp applications, such as halogen lamps, can be increased by including auxiliary circuits. Such auxiliary circuits may include gate drive resistors; a charge pump for sustaining the DC supply; open circuit protection; short circuit protection; thermal protection; extended resetting time; latched shutdown; self-dimming; a digital (DALI) interface; and line voltage compensation.

Claims

1. A power supply circuit for powering a load, comprising:

a half-bridge comprising a pair of high-side and low-side switching devices arranged in series between a high-side supply circuit and a common return circuit;

a connection point between said switching devices providing a switched output for powering said load;

an integrated circuit, including a high-side driver and a low-side driver for respectively providing drive signals to control terminals of said high- and low-side switching devices, said high- and low-side drivers being controlled by an oscillator and timing and logic elements in the integrated circuit; and

a protective circuit which responds to high dv/dt at the switched output by delivering a voltage peak to a current sense terminal of said IC;

wherein the protective circuit comprises a capacitor and a resistor connected in series to said switched output, and a diode with its cathode connected to a node of said capacitor and resistor, and its anode connected to said current sense terminal.

2. A power supply circuit of claim 1, wherein the protective circuit responds to an open circuit at said load.

3. A power supply circuit for powering a load, comprising:

a half-bridge comprising a pair of high-side and low-side switching devices arranged in series between a high-side supply circuit and a common return circuit;

a connection point between said switching devices providing a switched output for powering said load; and

an integrated circuit, including a high-side driver and a low-side driver for respectively providing drive signals to control terminals of said high- and low-side switching devices, said high- and low-side drivers being controlled by an oscillator and timing and logic elements in the integrated circuit; and

a peak detecting circuit which regulates output voltage by feeding back the load voltage to the current sense pin of the IC, whereby the oscillator frequency increases and the load voltage decreases in response to peaks of said load voltage;

wherein said IC has a latched shutdown mode;

further comprising a latched shutdown trigger circuit which responds to a short circuit condition at said switched output by placing said IC in said latched shutdown mode.

4. A power supply circuit of claim 3, wherein said latched shutdown mode is entered in response to a voltage above a given threshold applied to a current sense pin for a given time, and wherein said trigger circuit applies said given voltage to said current sense pin for said given time so that said IC enters said latched shutdown in response to a short circuit.

5. A power supply circuit of claim 3, further comprising a delay circuit for delaying said response of said latched shutdown trigger circuit.

6. A power supply circuit of claim 3, wherein said trigger circuit comprises:

a triggerable device connected between a main IC voltage bus and a common bus; and

a sensing circuit which delivers a trigger signal to said triggerable device in response to a short circuit;

whereby a short circuit causes said triggerable device to pull down said IC bus voltage.

7. A power supply circuit of claim 6, wherein said triggerable device comprises an SCR and said sensing circuit senses an overcurrent in said half-bridge.

8. A power supply circuit of claim 7, further comprising a delay circuit for delaying said response of said latched shutdown trigger circuit.

9. A power supply circuit of claim 3, wherein said feedback voltage increases the oscillator frequency and thereby decreases the load voltage in response to peaks of said load voltage.

10. A power supply circuit of claim 9, wherein said load voltage is taken at the secondary of a transformer whose primary is connected to said switched output voltage of said half-bridge.

11. A power supply circuit of claim 3, wherein said feedback voltage increases the duty cycle of a periodic waveform applied to said current sense pin and thereby increases the oscillator frequency and decreases the load voltage in response to peaks of said load voltage.

12. A power supply circuit of claim 11, wherein said load voltage is taken at the secondary of a transformer whose primary is connected to said switched output voltage of said half-bridge.

13. A power supply circuit of claim 3, wherein said peak detecting circuit feeds back a voltage taken at a secondary of a transformer whose primary is connected to said switched output voltage of said half-bridge, said load power being supplied by another secondary of said transformer.

14. A method of supplying power to a load, using:

a half-bridge comprising a pair of high-side and low-side switching devices arranged in series between a high-side supply circuit and a common return circuit;

a connection point between said switching devices providing a switched output for powering said load; and

an integrated circuit, including a high-side driver and a low-side driver for respectively providing drive signals to control terminals of said high- and low-side switching devices, said high- and low-side drivers being controlled by an oscillator and timing and logic elements in the integrated circuit;

said method comprising the step of protecting said IC by delivering a voltage peak to a current sense terminal of said IC in response to high dv/dt at the switched output by a capacitor and a resistor connected in series to said switched output, and a diode with its cathode connected to a node of said capacitor and resistor, and its anode connected to said current sense terminal.

15. The method of claim 14, wherein said voltage peak is provided in response to an open circuit at said load.

16. A method of supplying power to a load, using:

a half-bridge comprising a pair of high-side and low-side switching devices arranged in series between a high-side supply circuit and a common return circuit;

a connection point between said switching devices providing a switched output for powering said load; and

an integrated circuit, including a high-side driver and a low-side driver for respectively providing drive signals to control terminals of said high- and low-side switching devices, said high- and low-side drivers being controlled by an oscillator and timing and logic elements in the integrated circuit; and

said method comprising the step of regulating output voltage by feeding back the load voltage to the current sense pin of the IC, whereby the oscillator frequency increases and the load voltage decreases in response to peaks of said load voltage;

wherein said IC has a latched shutdown mode; and

responding to a short circuit condition at said switched output by placing said IC in said latched shutdown mode by a latched shutdown trigger circuit.

17. The method of claim 16, wherein said latched shutdown mode is entered in response to a voltage above a given threshold applied to a current sense pin for a given time and wherein said trigger circuit applies said given voltage to said current sense pin for said given time so that said IC enters a latched shutdown in response to a short circuit.

18. The method of claim 16, further comprising a delay circuit for delaying said response of said latched shutdown trigger circuit.

19. The method of claim 16, wherein said trigger circuit comprises:

a triggerable device connected between a main IC voltage bus and a common bus; and

a sensing circuit which delivers a trigger signal to said triggerable device in response to a short circuit;

whereby a short circuit causes said triggerable device to pull down said IC bus voltage.

20. The method of claim 19, wherein said triggerable device comprises an SCR and said sensing circuit senses an overcurrent in said half-bridge.

21. The method of claim 20, further comprising a delay circuit for delaying said response of said latched shutdown trigger circuit.

22. The method of claim 16, wherein said feedback voltage increases the oscillator frequency and decreases the load voltage in response to peaks of said load voltage.

23. The method of claim 22, wherein said load voltage is taken at the secondary of a transformer connected to said switched output voltage of said half-bridge.

24. The method of claim 16, wherein said feedback voltage increases the duty cycle of a periodic waveform applied to said current sense pin and thereby increases the oscillator frequency and decreases the load voltage in response to peaks of said load voltage.

25. The method of claim 24, wherein said load voltage is taken at the secondary of a transformer connected to said switched output voltage of said half-bridge.

26. The method of claim 16, wherein said peak detecting circuit feeds back a voltage taken at a secondary of a transformer connected to said switched output voltage of said half-bridge, said load power being supplied by another secondary of said transformer.