Asymmetric topology to boost low load efficiency in multi-phase switch-mode power conversion

Abstract

Techniques for performing DC to DC power conversion in switch-mode converter circuits include combinations of dynamic switch shedding, phase shedding, symmetric phase circuit topologies, and asymmetric phase circuit topologies. In at least one embodiment of the invention, a method of operating a power converter circuit includes operating a first phase switch circuit portion using a first number of switch devices when the power converter circuit is configured in a first mode of operation. The first number is greater than zero. The method includes operating the first phase switch circuit portion using the first number of switch devices when the power converter circuit is configured in a second mode of operation. The method includes operating a second phase switch circuit portion using a second number of switch devices when the power converter circuit is configured in the second mode of operation. The second number is greater than the first number.

1 . A method of operating a multi-phase switched power converter circuit comprising:
 operating a first switch circuit using a first number of switch devices when the power converter circuit is in a first mode of operation, the first number being greater than zero; and   operating a second switch circuit using a second number of switch devices when the power converter circuit is in first mode of operation, the second number being greater than the first number.   
     
     
         2 . The method, as recited in  claim 1 , further comprising:
 operating the second switch circuit portion with the first number of switch devices when the power converter circuit is in a second mode of operation.   
     
     
         3 . The method, as recited in  claim 2 , further comprising:
 selecting the second mode of operation as a next mode of operation when the power converter circuit is in the first mode of operation and in response to a reduction in output power.   
     
     
         4 . The method, as recited in  claim 2 , further comprising:
 operating the first switch circuit with a third number of switch devices when the power converter circuit is in a third mode of operation, the third number being greater than the first number; and   operating the second switch circuit with the third number of switch devices in the third mode of operation.   
     
     
         5 . The method, as recited in  claim 4 , further comprising:
 selecting the first mode of operation as a next mode of operation in response to a reduction in output power and when the power converter circuit is in the second mode of operation or the third mode of operation.   
     
     
         6 . The method, as recited in  claim 4 , wherein when the power converter circuit is in the third mode of operation, the second switch circuit is configured to be inoperable. 
     
     
         7 . The method, as recited in  claim 2 , wherein the first mode is a low power mode and the second mode is a higher power mode. 
     
     
         8 . The method, as recited in  claim 1 , wherein an efficiency of the first switch circuit is greater than an efficiency of the second switch circuit for a low output current mode and the efficiency of the second switch circuit is greater than the efficiency of the first switch circuit for a high output current mode. 
     
     
         9 . The method, as recited in  claim 2 , further comprising:
 selecting a mode of operation at least partially based on a feedback signal, the mode of operation being selected from a plurality of modes of operation including at least the first and second modes of operation.   
     
     
         10 . The method, as recited in  claim 1 , further comprising:
 reducing a total number of active switch devices in the power converter circuit prior to reducing a number of active phase circuits of a plurality of phase circuits in response to a reduction in output power.   
     
     
         11 . The method, as recited in  claim 1 , further comprising:
 allocating current to individual switch circuits at least partially based on a selected mode of operation of the power converter circuit.   
     
     
         12 . A method of operating a multi-phase, switched power converter circuit comprising:
 selectively disabling at least one switch device of a plurality of switch devices in a first phase circuit of a plurality of phase circuits   while at least one other switch device of the first phase circuit is selectively enabled.   
     
     
         13 . The method, as recited in  claim 12 , wherein the selectively enabled switch devices form an asymmetric power converter circuit wherein the first circuit portion having, has a different number of enabled switch devices than a second phase circuit of the plurality of phase circuits. 
     
     
         14 . The method, as recited in  claim 12 , further comprising:
 reducing a total number of active switch pairs in the power converter circuit prior to reducing the number of active phase circuits in response to an increasing reduction in output power.   
     
     
         15 . The method, as recited in  claim 12 , further comprising:
 distributing current provided by the power converter circuit to individual phase circuits according to a number of switch devices selectively disabled in individual phase circuits.   
     
     
         16 . An apparatus comprising:
 a multi-phase switched power converter circuit comprising:   a first switch circuit to operate using a first number of switch devices when the power converter circuit is in a first mode of operation, the first number being greater than zero; and   at least a second switch circuit to operate using a second number of switch devices when the power converter circuit is in the first mode of operation, the second number being greater than the first number.   
     
     
         17 . The apparatus, as recited in  claim 16 , wherein the second switch circuit is configured to operate using the first number of switch devices when the power converter circuit is configured in a second mode of operation. 
     
     
         18 . The apparatus, as recited in  claim 17 , wherein the first switch circuit is configured to operate with a third number of switch devices when the power converter circuit is in a third mode of operation, the third number being greater than the first number, and wherein the second switch circuit is configured to operate with the third number of switch devices when the power converter circuit is in the third mode of operation. 
     
     
         19 . The apparatus, as recited in  claim 18 , wherein the second switch circuit is configured to be inoperable when the power converter circuit is in the third mode of operation. 
     
     
         20 . The apparatus, as recited in  claim 17 , wherein the first mode of operation is a low power mode and the second mode of operation is a higher power mode. 
     
     
         21 . The apparatus, as recited in  claim 16 , wherein an efficiency of the first switch circuit is greater than an efficiency of the second switch circuit for a low output current and the efficiency of the second switch circuit is greater than the efficiency of the first switch circuit for a high output current. 
     
     
         22 . The apparatus, as recited in  claim 17 , further comprising:
 a controller circuit portion configured to select a mode of operation at least partially based on a feedback signal, the mode of operation being selected from a plurality of modes of operation including at least the first and second modes of operation; and   a node coupled to a first phase circuit comprising the first switch circuit and coupled to a second phase circuit comprising the second switch circuit, the node being configured to deliver power to a load.   
     
     
         23 . The apparatus, as recited in  claim 22 , wherein the controller circuit is configured to select a mode of operation with a reduced total number of active switch pairs in the power converter circuit prior to selecting a mode of operation with a reduced number of active phase circuits in response to an increasing reduction in output power. 
     
     
         24 . The apparatus, as recited in  claim 16 , wherein the power converter circuit further is to enable the first switch circuit during a first phase and enable the second switch circuit during the first phase. 
     
     
         25 . The apparatus, as recited in  claim 16 , wherein the power converter circuit further is to enable the first switch circuit during a first phase and enable the second switch circuit during a second phase. 
     
     
         26 . The method, as recited in  claim 1 , further comprising:
 enabling the first switch circuit during a first phase; and   enabling the second switch circuit during the first phase.   
     
     
         27 . The method, as recited in  claim 1 , further comprising:
 enabling the first switch circuit during a first phase; and   enabling the second switch circuit during a second phase.   
     
     
         28 . The method, as recited in  claim 12 , further comprising:
 selectively disabling the at least one switch device of a plurality of switch devices in a second phase circuit while at least one other switch device of the second phase circuit is selectively enabled.   
     
     
         29 . The method, as recited in  claim 12 , wherein at least one of the selectively disabling at least one switch device and the selectively enabling the at least one other switch device is at least partially based on a load coupled to the power converter circuit. 
     
     
         30 . An apparatus comprising:
 a multi-phase switched power converter circuit comprising:
 a plurality of phase circuits, each phase circuit comprising a plurality of switch pairs; and 
 a controller to selectively enable individual switch pairs of at least one phase circuit of the plurality of phase circuits based on a mode of operation of the power converter circuit. 
   
     
     
         31 . The apparatus, as recited in  claim 30 , wherein the controller is further configured to:
 select the mode of operation at least partially based on a feedback signal representing an output current of the power converter circuit.   
     
     
         32 . The apparatus, as recited in  claim 30 , wherein the controller is further configured to:
 enable a first number of switch pairs in a first phase circuit of the plurality of phase circuits in a first mode of operation, the first number greater than zero; and   enable a second number of switch pairs in the first phase circuit in a second mode of operation, the second number different than the first mode.   
     
     
         33 . The apparatus, as recited in  claim 32 , wherein the controller is further configured to:
 enable a third number of switch pairs in a second phase circuit of the plurality of phase circuits in the second mode of operation, the third number different than the second number.   
     
     
         34 . The apparatus, as recited in  claim 32 , wherein the controller is further configured to:
 disable a second phase circuit of the plurality of phase circuits in the second mode of operation.   
     
     
         35 . The apparatus, as recited in  claim 30 , further comprising:
 a passive circuit portion selected from the group consisting of a resistor, capacitor and an inductor.