Boost power supply sequencing

1. A boost power supply comprising:

a plurality of switching power supplies, each switching power supply of the plurality of switching power supplies configured to source a respective portion current of a combined output current provided by the boost power supply to a load at an output of the boost power supply; and

control circuitry configured to:

control each switching power supply by a different respective switch control signal of a plurality of switch control signals to regulate the respective portion current sourced by the switching power supply to provide a different percentage of the combined output current at any given time than a percentage of the combined output current provided by another one of the plurality of switching power supplies at the given time; and

assert each different respective switch control signal of the plurality of switch control signals out of phase with respect to each other different respective switch control signal, and simultaneously with at least one other different respective switch control signal for at least a specified duration, such that the combined output current is prevented from exceeding a specified threshold current value while maintaining at least a specified average current draw from the boost power supply.

2. The boost power supply of claim 1 , wherein the control circuitry is configured to assert the plurality of switch control signals sequentially.

3. The boost power supply of claim 1 , wherein in asserting the plurality of switch control signals sequentially, the control circuitry is configured to assert each subsequent different respective switch control signal 90 degrees out of phase with respect to an asserted different respective switch control signal immediately preceding the subsequent different respective switch control signal.

4. The boost power supply of claim 1 , wherein each different switch control signal is a pulse width modulated (PWM) signal.

5. The boost power supply of claim 4 , wherein each different switch control signal has a duty-cycle value that is greater than 50%.

6. The boost power supply of claim 1 , wherein each switching power supply comprises:

an input power source;

a capacitor; and

a transformer having a primary winding and a secondary winding, wherein the primary winding comprises:

a first end coupled to the input power source; and

a second end coupled to a switching element controlled by a corresponding different respective switch control signal to switchably power the primary winding;

wherein the secondary winding comprises:

a first end coupled to the capacitor; and

a second end coupled to ground.

7. The boost power supply of claim 6 , wherein each switching power supply has three operating modes:

an on-mode;

an off-mode; and

a stopped-mode.

8. The boost power supply of claim 7 ;

wherein during on-mode current is drawn from the input power source into the primary winding;

wherein during off-mode the switching element is operated to stop current from flowing in the primary winding; and

wherein during stopped-mode, energy in the transformer is transferred from the secondary winding to the capacitor.

9. The boost power supply of claim 8 , wherein the control circuitry is configured to return the switching power supply to the on-mode as soon as the energy in the transformer is transferred to the capacitor.

10. The boost power supply of claim 1 , wherein the control circuitry is configured to keep each different respective switch control signal asserted until a current in the corresponding switching power supply controlled by the respective switch control signal reaches a preset threshold value.

11. The boost power supply of claim 1 , wherein the control circuitry is configured to keep each different respective switch control signal unasserted until one or more of the following conditions are met:

energy stored in a transformer of the switching power supply has been discharged from the transformer; or

a minimum time has been met to achieve a specified phase offset in a switching order of the plurality of switching power supplies.

12. A method for providing power at a power terminal, the method comprising:

operating a plurality of switching power supplies, comprising operating each switching power supply of the plurality of switching power supplies to source a respective portion current of a combined output current provided to a load at the power terminal;

regulating the respective portion current sourced by each switching power supply to provide a different percentage of the combined output current at any given time than a percentage of the combined output current provided by another one of the plurality of switching power supplies at the given time, comprising controlling the switching power supply by a different respective switch control signal of a plurality of switch control signals; and

asserting each different respective switch control signal of the plurality of switch control signals out of phase with respect to each other different respective switch control signal, comprising simultaneously asserting the different respective switch control signal with at least one other different respective switch control signal for at least a specified duration, such that the combined output current is prevented from exceeding a specified threshold current value while maintaining at least a specified average current draw at the power terminal.

13. The method of claim 12 , wherein said operating comprises sequentially asserting the plurality of switch control signals.

14. The method of claim 12 , wherein said sequentially asserting the plurality of switch control signals comprises asserting each different respective switch control signal 90 degrees out of phase subsequent to asserting a most recent previous different respective switch control signal.

15. The method of claim 12 , wherein each different switch control signal is a pulse width modulated (PWM) signal.

16. The method of claim 15 , wherein each different switch control signal has a duty-cycle value that is greater than 50%.

17. The method of claim 12 , wherein each switching power supply comprises:

an input power source;

a capacitor; and

a transformer having a primary winding and a secondary winding, wherein the primary winding comprises:

a first end coupled to the input power source; and

a second end coupled to a switching element controlled by a corresponding different respective switch control signal to switchably power the primary winding;

wherein the secondary winding comprises:

a first end coupled to the capacitor; and

a second end coupled to ground.

18. The method of claim 17 , wherein said operating comprises operating each switching power supply in three operating modes:

an on-mode;

an off-mode; and

a stopped-mode.

19. The method of claim 18 , wherein said operating the switching power supply in the on-mode comprises drawing current from the input power source into the primary winding.

20. The method of claim 18 , wherein said operating the switching power supply in the off-mode comprises operating the switching element to stop current from flowing in the primary winding.

21. The method of claim 18 , wherein said operating the switching power supply in the stopped-mode comprises transferring energy in the transformer from the secondary winding to the capacitor.

22. The method of claim 21 , further comprising returning the switching power supply to the on-mode as soon as said transferring the energy to the capacitor is complete.

23. The method of claim 12 , wherein said controlling the switching power supply by a different respective switch control signal comprises:

asserting the different respective switch control signal until a current in the corresponding switching power supply controlled by the respective switch control signal reaches a preset threshold value.

24. The method of claim 12 , wherein said controlling the switching power supply by a different respective switch control signal comprises:

holding the different respective switch control signal unasserted until one or more of the following conditions are met:

energy stored in a transformer of the switching power supply has been discharged from the transformer; or

a minimum time has been met to achieve a specified phase offset in a switching order of the plurality of switching power supplies.