METHOD FOR INHIBITING THERMAL RUN-AWAY

• US 20070290664A1
• Filed: 06/16/2006
• Published: 12/20/2007
• Est. Priority Date: 06/16/2006
• Status: Active Grant

• Current Assignee: Semiconductor Components Industries LLC (ON Semiconductor Corporation)
• Original Assignee: Semiconductor Components Industries LLC (ON Semiconductor Corporation)
• Inventors: Moyer, Ole P., Gass, Christopher J., Harriman, Paul J., Rice, Benjamin M.
• Granted Patent: US 7,759,918 B2
• Time in Patent Office: Days
• US Class Current: 323/272
• CPC Class Codes: H02M 1/32 Means for protecting converters other than automatic disconnection
• CPC Class Codes: H02M 3/1584 with a plurality of power processing stages connected in parallel

Abstract

A method for method for inhibiting thermal run-away in a multi-phase power converter at varying load transition rates. A multi-phase power converter having an on-time is provided and the frequency of the multi-phase power converter is adjusted so that a load step period and the on time of the multi-phase power converter are in a temporal relationship. Alternatively, a load step rate is inhibited from locking onto a phase current of the multi-phase power converter by suspending an oscillator signal. In accordance with another alternative, a load step rate is inhibited from locking onto a phase current of the multi-phase power converter by suspending an oscillator signal and dithering an input signal to the oscillator.

Claims

1. A method for balancing current in a multi-phase power converter at varying load transition rates, comprising:

providing the multi-phase power converter having an on-time; and

adjusting the frequency of the multi-phase power converter so that a load step period and the on-time of the multi-phase power converter are in a temporal relationship.

2. The method of claim 1, wherein the temporal relationship is one of coincident, similar, or the same.

3. The method of claim 1, wherein providing the multi-phase power converter includes:

providing an error amplifier having an output;

providing an oscillator having an output;

coupling the output of the error amplifier to a first input of a pulse width modulator;

coupling the output of the oscillator to a second input of the pulse width modulator; and

providing a first power stage having an input coupled to an output of the pulse width modulator.

4. The method of claim 3, further including:

coupling a second power stage having an input to another output of the pulse width modulator;

coupling a first inductor between the output of the first power stage and an output node;

coupling a second inductor between the output of the second power stage and the output node; and

coupling the output node to an input of the error amplifier.

5. The method of claim 1, wherein the temporal relationship between the on-time of the multi-phase power converter and the load step is a coincidental relationship.

6. The method of claim 1, wherein the multi-phase power converter is a 4-phase power converter.

7. The method of claim 1, wherein the multi-phase power converter is one of a 2-phase power converter or a 3-phase power converter.

8. The method of claim 1, further including coupling a dither circuit to the multi-phase power converter.

9. The method of claim 1, wherein adjusting the on-time of the multi-phase power converter includes dithering an oscillator signal.

10. The method of claim 1, wherein adjusting the on-time of the multi-phase power converter includes one of suspending an oscillator signal or phase shifting the oscillator signal.

11. A method for inhibiting thermal run-away in a multi-phase power converter at varying load transition rates, comprising operating the multi-phase power converter to inhibit a load step rate from locking onto a phase current of the multi-phase power converter.

12. The method of claim 11, wherein operating the multi-phase power converter includes suspending an oscillator signal.

13. The method of claim 11, wherein operating the multi-phase power converter includes dithering an output signal of the multi-phase power converter.

14. The method of claim 13, wherein operating the multi-phase power converter further includes suspending an oscillator signal.

15. The method of claim 11, further including a multi-phase power converter selected from the group of multi-phase power converters comprising a 2-phase power converter, a 3-phase power converter, and a 4-phase power converter.

16. The method of claim 11, further including:

generating a circuit output voltage from a multi-phase power converter output voltage; and

generating a compensation voltage from the circuit output voltage.

17. The method of claim 16, further including comparing the compensation voltage with at least one oscillator signal to generate a pulse width modulated signal.

18. The method of claim 17, wherein comparing the compensation voltage with at least one oscillator signal includes comparing the compensation voltage with a plurality of oscillator signals to generate a plurality of pulse width modulated signals.

19. A method for inhibiting thermal run-away in a multi-phase power converter at varying load transition rates, comprising operating the multi-phase power converter to inhibit a load step rate from locking onto a phase current of the multi-phase power converter by suspending an oscillator signal and dithering an input signal to the oscillator.

20. The method of claim 19, farther including a multi-phase power converter having n-phases where n is an integer.