Multiphase converter system and control method

1. A method comprising:

providing a power converter comprising a plurality of power phases, wherein:

each power phase comprises a power stage and a corresponding control circuit;

outputs of the plurality of power phases are connected together; and

each power stage is controlled by a constant-on time and minimum off-time control scheme using a pulse-width modulated signal generated by the corresponding control circuit in response to a trigger signal; and

configuring the plurality of power phases to operate in an interleaved manner by passing a token sequentially among the plurality of power phases, wherein the token represents an enable function for allowing a high-side switch of a power phase possessing the token to be turned on and the token is passed to a next power phase after a minimum off-time of the high-side switch.

2. The method of claim 1 , wherein:

the plurality of power phases are controlled by a first controller and a second controller; and

the first controller is configured as a master and the second controller is configured as a slave.

3. The method of claim 2 , wherein:

the power phases controlled by the master are turned on earlier than the power phases controlled by the slave.

4. The method of claim 2 , wherein:

the power phases controlled by the master are turned on sequentially; and

the power phases controlled by the slave are turned on sequentially.

5. The method of claim 2 , wherein:

the token is transferred among different phases controlled by the master in a predetermined manner; and

the token is transferred among different phases controlled by the slave in a predetermined manner.

6. The method of claim 5 , wherein:

the token is released from the master to the slave when a last power phase controlled by the master finishes.

7. The method of claim 1 , wherein:

each power phase comprises a step-down power converter.

8. The method of claim 1 , wherein:

the plurality of power phases are controlled by a single controller; and

the token is transferred between different phases by a counter.

9. The method of claim 8 , wherein:

the counter is configured to hand the token in a round robin fashion from a first power phase to a last power phase and repeat this process again after the last power phase finishes.

10. A method comprising:

configuring a plurality of power phases of a power converter to operate in an interleaved manner by passing a token sequentially among the plurality of power phases;

generating a first pulse-width modulated signal to turn on a first power phase after the first power phase possesses the token and receives a trigger signal from a control circuit of the first power phase;

after a pre-determined minimum off-time of the first power phase, passing the token to a second power phase to enable the second power phase;

after a pre-determined minimum off-time of the second power phase, passing the token sequentially until a last power phase of the plurality of power phases possesses the token; and

forwarding the token to the first power phase after the last power phase finishes.

11. The method of claim 10 , wherein:

each power phase comprises a power stage and a corresponding control circuit; and

outputs of the plurality of power phases are connected together.

12. The method of claim 10 , wherein:

the token represents an enable function for allowing a high-side switch of a power phase possessing the token to be turned on.

13. The method of claim 10 , wherein each power phase comprises a constant on-time power converter comprising:

a first switch and a second switch connected in series between an input power source and ground; and

an inductor connected between a common node of the first switch and the second switch, and an output of the constant on-time power converter.

14. The method of claim 10 , wherein:

the plurality of power phases are controlled by a first controller and a second controller;

the first controller is configured as a master and the second controller is configured as a slave;

the power phases controlled by the master are turned on earlier than the power phases controlled by the slave; and

the token is released from the master to the slave when a last power phase controlled by the master finishes.

15. The method of claim 10 , wherein:

the plurality of power phases are controlled by a single controller;

the token is transferred between different phases by a counter; and

the counter is configured to hand the token in a round robin fashion from the first power phase to the last power phase, and repeats this process again after the last power phase finishes.

16. A system comprising:

a plurality of power phases connected between an input power source and an output terminal, wherein each power phase comprises a constant on-time and minimum off-time power converter; and

a controller configured to generate constant on-time and minimum off-time gate drive signals for the plurality of power phases in response to a trigger signal, wherein the plurality of power phases are configured to operate in an interleaved manner by passing a token sequentially among the plurality of power phases,

wherein:

the token is generated and passed among the plurality of power phases by the controller;

the token represents an enable function for allowing a power phase possessing the token to be turned on; and

the token is passed to a next power phase after a pre-determined minimum off-time of the power phase possessing the token.

17. The system of claim 16 , wherein:

the controller comprises a first control unit and a second control unit;

a plurality of first power phases is controlled by the first control unit and a plurality of second power phases is controlled by the second control unit; and

the first control unit is configured as a master and the second control unit is configured as a slave.

18. The system of claim 17 , wherein:

the first power phases are turned on earlier than the second power phases.

19. The system of claim 16 , wherein:

the controller comprises a counter; and

the counter is configured to hand the token in a round robin fashion from a first power phase to a last power phase, and repeats this process again after the last power phase finishes.

20. The system of claim 16 , wherein the constant on-time and minimum off-time power converter comprises:

a first switch and a second switch connected in series between an input power source and ground; and

an inductor connected between a common node of the first switch and the second switch, and an output capacitor.