Current balancing in a multi-phase power supply

1. A power supply system comprising:

a set of multiple phases, each of the multiple phases in the set producing respective current to produce an output voltage to power a load;

a controller operable to:

produce, for each of the multiple phases in the set, a respective current value representative of an estimated amount of current supplied by a respective phase to the load in a first control cycle of activating the multiple phases, the respective current value for the respective phase generated based on an adjustment to a corresponding pulse width control signal controlling the respective phase; and

in a second control cycle of activating the multiple phases, modify an order of activating the multiple phases based on magnitudes of respective current values produced for the multiple phases in the first control cycle, the second control cycle occurring subsequent to the first control cycle;

wherein the controller is further operable to:

activate each of the multiple phases in the set in the first control cycle to produce the output voltage;

activate each of the multiple phases in the set in the second control cycle to produce the output voltage;

monitor the output voltage; and

modify the order of activating the phases in the second control cycle to be different than an order of activating the multiple phases in the first control cycle based on a combination of the monitored output voltage and comparison of the magnitudes of the respective current values produced for the multiple phases.

2. The power supply system as in claim 1 , wherein the controller is further operable to:

control the output voltage to be a target DC value;

monitor an AC component of the output voltage; and

modify the order of activating the multiple phases in the second control cycle based at least in part on the monitored AC component of the output voltage.

3. The power supply system as in claim 2 , wherein the controller is further operable to:

modify the order of activating the multiple phases in the second control cycle based on the magnitudes of respective current values in response to detecting that a frequency of the monitored AC component of the output voltage is above a threshold value.

4. The power supply system as in claim 3 , wherein the controller is further operable to modify the order of activating the phases in the second control cycle to balance magnitudes of respective current supplied by the multiple phases to the load over each of multiple control cycles of activating the multiple phases in the set.

5. The power supply system as in claim 1 , wherein the controller is further operable to:

while operating the controller in a first control mode, monitoring AC attributes of the output voltage while the controller operates in the first control mode; and

in response to detecting degradation of the AC attributes while in the first control mode, switching to operation of the multiple phases in a second control mode in which the controller modifies the order of activating the phases based on the magnitudes of respective current values produced for the multiple phases.

6. The method as in claim 1 , wherein the set of multiple phases includes a first phase and a second phase, the method further comprising:

implementing a first phase activation order in the first control cycle and implementing a second phase activation order in the second control cycle to balance contribution of current provided by the first phase and the second phase to the load.

7. The power supply system as in claim 1 , wherein the controller is further operable to modify the order of activating the phases from the first control cycle to the second control cycle to balance magnitudes of respective current supplied by the multiple phases to the load over time.

8. The power supply system as in claim 1 , wherein the multiple phases include a first phase and a second phase; and

wherein the controller is operative to apply a first pulse width adjustment value to a pulse width activation time of the first phase to produce a respective first current value indicating an amount of current supplied by the first phase to the load; and

wherein the controller is operative to apply a second pulse width adjustment value to a pulse width activation time of the second phase to produce a respective second current value indicating an amount of current supplied by the second phase to the load.

9. The power supply as in claim 8 , wherein the first pulse width adjustment value is derived based on a filtered first phase current; and

wherein the second pulse width adjustment value is derived based on a filtered second phase current.

10. The power supply as in claim 1 , wherein the multiple phases include i phases, the power supply further comprising:

an adjustment circuit operative to, for each i th phase:

i) receive a pulse width value (pw_i) for a respective phase i, the pulse width value pw_i indicating a time in which a corresponding high side switch in the i th phase is activated;

ii) receive an adjustment value pw_adjust_i, which is a filtered phase current value for the i th phase; and

iii) adjust the pulse width value (pw_i) by the adjustment value pw_adjust_i to estimate the amount of current supplied by the i th phase.

11. The power supply as in claim 10 , wherein the adjustment circuit sums the pulse width value pw_i to the adjustment value pw_adjust_i to produce the estimate of the amount of current supplied by the i th phase to the load.

12. A method comprising:

switching operation of a set of multiple phases in a power supply between a first control mode and a second control mode, each of the multiple phases in the set activated during both the first control mode and the second control mode to collectively produce an output voltage to power a load;

a) in the first control mode: repeatedly activating each of the multiple phases in the set as indicated by a first phase activation order; and

b) in the second control mode: activating the multiple phases in the set in a manner as indicated by a second phase activation order, the second phase activation order different than the first phase activation order, the second phase activation order derived based on magnitudes of estimated current produced by the multiple phases to power the load, a respective estimated current value for a respective phase of the multiple phases generated based on application of an adjustment value to a corresponding pulse width control signal controlling the respective phase.

13. The method as in claim 12 further comprising:

monitoring the output voltage; and

switching from operating the multiple phases in the first control mode to operating the multiple phases in the second control mode based on a detected variation in magnitude of the output voltage.

14. The method as in claim 12 further comprising:

in the first control mode:

controlling the output voltage to be a target DC value;

deriving an AC voltage component from the output voltage;

analyzing the AC voltage component; and

switching from operating the multiple phases in the first control mode to operating the multiple phases in the second control mode based at least in part on the AC voltage component.

15. The method as in claim 14 further comprising:

switching from operating the multiple phases in the first control mode to operating the multiple phases in the second control mode based at least in part on a magnitude of the AC voltage component of the output voltage.

16. The method as in claim 14 further comprising:

switching from operating the controller in the first control mode to operating the multiple phases in the second control mode based at least in part on a frequency of the AC voltage component of the output voltage.

17. The method as in claim 12 further comprising:

in the first control mode: modifying a respective duty cycle of activating each of the multiple phases over time to balance magnitudes of respective currents supplied by each of the multiple phases to the load over time; and

in the second control mode: modifying the second phase activation order of activating the phases to balance the magnitudes of respective currents supplied by the multiple phases over time to the load.

18. The method as in claim 12 further comprising:

selecting between the first control mode and the second control mode based on a ripple frequency of the output voltage.

19. The method as in claim 12 further comprising:

monitoring a magnitude of an input voltage used by the multiple phases to produce the output voltage that produces current to power the load;

monitoring a magnitude of the output voltage;

receiving pulse width modulation control setting information associated with the control of the multiple phases; and

applying the pulse width modulation control setting information to the magnitude of the input voltage and the magnitude of the output voltage to produce the respective current value for each of the multiple phases.

20. The method as in claim 12 further comprising:

in the first control mode, adjusting pulse width modulation control settings of the multiple phases based on magnitudes of current supplied by the multiple phases to the load; and

wherein adjusting the pulse width modulation control settings based on the magnitudes includes: balancing current supplied by the multiple phases to be within a range of each other.

21. The method as in claim 12 further comprising:

modifying the second phase activation order of activating the phases in the second control mode in order to balance the magnitudes of respective currents supplied by the multiple phases to the load over time.

22. The method as in claim 12 further comprising:

producing a respective estimated current value for each of the multiple phases, the respective estimated current value for each of the multiple phases representing a corresponding estimated amount of AC current supplied by that phase to the load.

23. The method as in claim 12 further comprising:

operating the controller in the second control mode in response to detecting a transient change in consumption of current by the load above a threshold value.

24. The method as in claim 12 further comprising:

controlling the output voltage to be a target DC value; and

operating the controller in the second control mode in response to detecting that a magnitude of an AC voltage component of the output voltage is above a threshold value.

25. The method as in claim 12 further comprising:

operating the controller in the second control mode in response to current consumption of the load above a threshold value.

26. The method as in claim 12 further comprising:

producing a first current value indicating current delivered by a first phase of the multiple phases to the load;

producing a second current value indicating current delivered by a second phase of the multiple phases to the load; and

producing the second phase activation order of activating the multiple phases based on comparing the first current value and the second current value.

27. The method as in claim 26 further comprising:

activating each of the multiple phases in the set for each control cycle of multiple control cycles to produce the output voltage.

28. The method as in claim 27 further comprising:

as specified by the first phase activation order, activating each of the multiple phases in the set for a first control cycle of the multiple control cycles; and

as specified by the second phase activation order, activating each of the multiple phases in the set for a second control cycle of the multiple control cycles, the second phase activation order different than the first phase activation order.