MULTIPHASE POWER CONVERSION USING SKEWED PER-PHASE INDUCTOR CURRENT LIMITS

• US 20150288285A1
• Filed: 03/31/2015
• Published: 10/08/2015
• Est. Priority Date: 04/02/2014
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: Apple Inc.
• Inventors: Paul, Rajarshi, Patel, Parin, Houk, Talbott M.
• Granted Patent: US 9,923,468 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• 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 1/0032 Control circuits allowing low power mode operation, e.g. in standby mode
• CPC Class Codes: H02M 1/40 Means for preventing magnetic saturation
• CPC Class Codes: H02M 3/1566 with means for compensating against rapid load changes, e.g. with auxiliary current source, with dual mode control or with inductance variation
• CPC Class Codes: H02M 3/158 including plural semiconductor devices as final control devices for a single load
• CPC Class Codes: H02M 3/1584 with a plurality of power processing stages connected in parallel
• CPC Class Codes: Y02B 70/10 Technologies improving the efficiency by using switched-mode power supplies [SMPS], i.e. efficient power electronics conversion e.g. power factor correction or reduction of losses in power supplies or efficient standby modes

Abstract

A power conversion circuit has multiple phases wherein each of the phases has an inductor coupled to a power switch circuit and is coupled to an output node. A power conversion controller controls the switching of one or more of the phases to yield a regulated voltage on the output node. The controller uses a variable inductor current limit for one or more designated phases, and temporarily increases the variable inductor current limit during a transient condition. Other embodiments are also described and claimed.

Claims

1. A switching power conversion circuit comprising:

a plurality of phases, wherein each of the phases has an inductor coupled to a power switch circuit, the plurality of phases each being coupled to an output node; and

a power conversion controller coupled to control switching of one or more of the phases to yield a regulated voltage on the output node, and wherein the controller uses a variable inductor current limit for one or more of the phases and temporarily increases the variable inductor current limit during a transient condition.

2. The power conversion circuit of claim 1 wherein the inductor of the phase that is controlled in accordance with the variable inductor current limit has smaller inductance and higher saturation current than the inductor of another one of the phases.

3. The power conversion circuit of claim 1 wherein the inductor of said another one of the phases has greater inductance than that of the inductor of the phase that is controlled in accordance with the variable inductor current limit by at least a factor of four.

4. The power conversion circuit of claim 1 wherein the controller controls switching of said one or more of the phases to yield the regulated voltage in such a way that inductor current of said one or more of the phases does not exceed the variable inductor current limit.

5. The power conversion circuit of claim 1 wherein the controller comprises a detector circuit that detects a change in a load on the output node, the controller responds to the detection by increasing the variable inductor current limit.

6. The power conversion circuit of claim 5 wherein the controller comprises a timer that is started in response to the detection, the controller responds when the timer expires, by decreasing the variable inductor current limit.

7. The power conversion circuit of claim 1 wherein the plurality of phases are all part of a single-controller multi-phase power converter.

8. The power conversion circuit of claim 1 wherein the designated phase remains inactive until a) a load on the output node exceeds a threshold, or b) the controller exits a pulse frequency modulation (PFM) mode of operation.

9. The power conversion circuit of claim 1 wherein the controller increases the variable inductor current limit to a saturation current level of the inductor of said one or more phases, when voltage of the output node drops because of a load change, and then decreases the variable inductor current limit to less than the saturation current level when the voltage has settled.

10. A power management circuit comprising:

a switching voltage regulator controller having a plurality of phase control outputs, the controller to operate in a normal control mode to yield a regulated voltage on an output node associated with the phase control outputs,

the controller increases an inductor current limit of one or more of the phases when changing from the normal control mode to a transient control mode so that said one or more of the phases has a different inductor current limit than that of another.

11. The power management circuit of claim 10 wherein the controller comprises a detector circuit that uses a threshold to detect a change in a load on the output node, the controller responds to the detection by changing from the normal control mode to the transient control mode.

12. The power management circuit of claim 10 wherein the controller decreases the inductor current limit of said one or more of the phases when changing from the transient control mode to the normal control mode.

13. The power management circuit of claim 11 wherein the controller comprises a timer that is started in response to the detection, wherein the controller responds when the timer stops by changing from the transient control mode back to the normal control mode, and wherein the controller decreases the inductor current limit when changing from the transient control mode back to the normal control mode.

14. The power management circuit of claim 12 wherein the controller increases the inductor current limit of said one or more of the phases to be higher than an inductor current limit of another one of the phases.

15. The power management circuit of claim 10 wherein the controller comprises storage that contains a programmable value which is indicative of the increased inductor current limit.

16. A method for providing a regulated voltage, comprising:

performing switching control of a plurality of phase currents that are feeding an output node, while the output node exhibits a regulated voltage and one of the phase currents remains at or below its normal limit; and

performing switching control of the plurality of phase currents, while a) the output node exhibits a transient voltage drop due to a load change and, simultaneously, b) said one of the phase currents goes above its normal limit.

17. The method of claim 16 further comprising:

detecting the load change and in response allowing said one of the phase currents to temporarily reach a higher limit, and when the transient voltage drop has dissipated the phase current drops back to its normal limit.

18. The method of claim 16 wherein the higher limit is at least twenty percent greater than the normal limit.

19. The method of claim 16 wherein while the output node exhibits the transient voltage drop, another one of the phase currents remains at or below its normal limit.

20. A battery powered portable electronic device comprising:

a housing having installed therein

a data processor having a power supply input;

a battery; and

a dc-dc multi-phase switching power converter having

an input coupled to the battery, an output coupled to the power supply input of the data processor, a plurality of phases of which at least one is a designated phase that has lower inductance and higher inductor saturation current than another one of the phases, and a switch mode power conversion controller having a variable inductor current limit for the designated phase, wherein the controller temporarily raises the variable inductor current limit for the designated phase, during a transient voltage drop at the output, and then lowers the variable inductor current limit once the transient voltage drop has passed.

21. The device of claim 20 wherein the controller does not change a current limit for said another one of the phases during the transient voltage drop and once the transient voltage drop has passed.

22. The device of claim 21 wherein the designated phase remains inactive while a load on the output is smaller than a threshold, and is activated only when the load is greater than the threshold.