Voltage supply circuits and controlling methods therefor

This Application is a National Stage of International Patent Application Serial No. PCT/CN2015/070684, filed Jan. 14, 2015, entitled “VOLTAGE SUPPLY CIRCUITS AND CONTROLLING METHODS THEREFOR, ” which claims the benefit of U.S. Provisional Application No. 61/927,155, filed on Jan. 14, 2014, the contents of which are incorporated herein by reference.

The invention relates to a voltage supply circuit, and more particularly, to a multi-phase voltage supply circuit with enhanced efficiency in less-loading states.

In a multi-phase voltage supplier, there are several inductors coupled to an output node of the voltage supplier. The number of inductors is determined according to the loading of the voltage supplier. However, one factor of the power loss of the voltage supplier is the resistance values of the inductors. There are two different types of resistance values for one inductor: an AC resistance (ACR) and a DC resistance (DCR). Thus, in a multi-phase voltage supplier, how to set inductance values of inductors appropriately for enhanced efficiency is an important issue.

Thus, it is desirable to provide a voltage supply circuit which enhanced efficiency by enabling different inductors in different loading states.

An exemplary embodiment of a voltage supply circuit is provided. The voltage supply circuit is capable of operating at a first mode and generates a loading current at an output node. The voltage supply circuit comprises a plurality of inductors and a plurality of drier circuits. The plurality of inductors are coupled to the output node. Each inductor has an inductance value. The plurality driver circuits are coupled to the plurality of inductors respectively. The inductance value of a first inductor among the plurality of inductors is greater than the inductance values of the other inductor.

In an embodiment, for each driver circuit, when the driver circuit is enabled, the driver circuit generates a driving voltage to the corresponding inductor. Among the plurality of driver circuits, a first driver circuit is coupled to the first inductor. When the voltage supply circuit operates at the first mode, only the first driver circuit is enabled to generate the driving voltage to the first inductor.

In another embodiment, when the voltage supply circuit operates at a second mode, at least two driver circuits of the plurality of driver circuits are enabled to generate driving voltages to the corresponding inductors.

Another exemplary embodiment of a controlling method for a voltage supply circuit is provided. The voltage supply circuit generates a loading current at an output node of the voltage supply circuit. The voltage supply circuit comprises a plurality of inductors coupled to the output node. The controlling method comprises steps of when a value of the loading current is less than a first threshold, controlling the voltage supply circuit to generate a first driving voltage to a first inductor among the plurality of inductors; and when the value of the loading current is greater than the first threshold and less than a second threshold, controlling the voltage supply circuit to generate the first driving voltage to the first inductor and generate a second driving voltage to a second inductor among the plurality of inductors. An inductance value of the first inductor is greater than an inductance value of the second inductor.

In an embodiment, the controlling method further comprises when the value of the loading current is greater than the second threshold and less than a third threshold, controlling the voltage supply circuit to generate the first driving voltage to the first inductor, generate the second driving voltage to the second inductor, and generate a third driving voltage to a third inductor among the plurality of inductors. The inductance value of the first inductor is greater than an inductance value of the third inductor.

A detailed description is given in the following embodiments with reference to the accompanying drawings.

The invention can be more fully understood by reading the subsequent detailed description and examples with references made to the accompanying drawings, wherein:

FIG. 1 shows an exemplary embodiment of a voltage supply circuit;

FIG. 2 shows relationship between the number of valid inductors and the different modes at which the voltage supply circuit in FIG. 1 operates by depending on a loading current;

FIG. 3 shows an exemplary embodiment of a curve of relationship between efficiency and a loading current of the voltage supply circuit of FIG. 1 ; and

FIG. 4 shows an exemplary embodiment of a controlling method.

The following description is of the best-contemplated mode of carrying out the invention. This description is made for the purpose of illustrating the general principles of the invention and should not be taken in a limiting sense. The scope of the invention is best determined by reference to the appended claims.

In an exemplary embodiment of voltage supply circuit as shown in FIG. 1 , a voltage supply circuit 1 comprises a plurality of driver circuits 10 and a plurality of inductors 11 . In the embodiment, there are four driver circuits 10 A- 10 D and four inductors 11 A- 11 D for an example. Referring to FIG. 1 , the driver circuits 10 A- 10 D are coupled to the inductors 11 A- 11 D respectively, and all the inductors 11 A- 11 D are coupled to an output node NOUT of the voltage supply circuit 1 . According to the structure of the voltage supply circuit 1 , there are four paths for providing an output voltage VOUT/loading current IL to the output node NOUT, and the four paths operate in four different phases respectively. Thus, the voltage supply circuit 1 is referred to as a multi-phase voltage suppler circuit.

Each driver circuit generates a driving voltage to the corresponding inductor when the driver circuit is enabled. The situation where an inductor receives a driving voltage indicates that the inductor is valid. In the embodiment, the number of driver circuits being enabled at the same time is determined according to the loading current IL which is related to the loading state of the voltage supply circuit 1 . The loading current IL is proportional to the loading state of the voltage supply circuit 1 . In other words, the number of valid inductors is determined according to the loading current IL. When an inductor receives a corresponding driving voltage, an inductor current is generated. FIG. 2 shows relationship between the number of valid inductors and the different modes at which the voltage supply circuit 1 operates in different loading current IL. Referring to FIG. 2 , in order to make the voltage supply circuit 1 to operate at different modes, three thresholds VTH 1 -VTH 3 are available for the loading current IL, wherein VTH 1 <VTH 2 <VTH 3 . When the loading current IL is smaller than the threshold VTH 1 (first mode M 20 ), the number of valid inductors is equal to one (such as the inductor 11 A). That is, only one driver circuit among the driver circuit 10 A- 10 D is enabled to generate a driving voltage V 10 A to the corresponding inductor 11 A. When the loading current IL is smaller than the threshold VTH 2 and larger than the threshold VTH 1 (second mode M 21 ), the number of valid inductors is equal to two (such as the inductors 11 A and 11 B). That is, two driver circuits among the driver circuit 10 A- 10 D are enabled to generate driving voltages V 10 A and V 10 B to the corresponding inductors 11 A and 11 B respectively. When the loading current IL is smaller than the threshold VTH 3 and larger than the threshold VTH 2 (third mode M 22 ), the number of valid inductor is equal to three (such as the inductors 11 A- 11 C). That is, three driver circuits among the driver circuit 10 A- 10 D are enabled to generate driving voltages V 10 A-V 10 C to the corresponding inductors 11 A- 11 C respectively. When the loading current IL is larger than the threshold VTH 3 (fourth mode M 23 ), the number of valid inductor is equal to four (such as the inductors 11 A- 11 D). That is, all of the driver circuits 10 A- 10 D are enabled to generate driving voltages V 10 A-V 10 D to the corresponding inductors 11 A- 11 D respectively.

Each of the inductors 11 A- 11 D has two different resistance values: an AC resistance (ACR) value and a DC resistance (DCR) value. Both of the resistance values influence the efficiency of the voltage supply circuit 1 . For each inductor, when the loading of the voltage supply circuit 1 is small (that is the loading current is small), the power loss induced by the ACR value of the inductor dominates the power loss of the voltage supply circuit 1 . In this case, the inductor may have a great inductance value to decrease the ripple on the inductor current flowing through the inductor, thereby getting higher efficiency for the voltage supply circuit. In another case, when the loading is great (that is the loading current is larger), the power loss induced by the DCR value of the inductor dominates the power loss. At this time, the inductor may have a less inductance value to decrease the average value of the inductor current flowing through the inductor, thereby getting higher efficiency for the voltage supply circuit. Thus, in the voltage supply circuit 1 of the embodiment, the inductors 11 A- 11 D are set to specific inductance values for enhanced efficiency.

According to the above description, when the loading current IL is small, only the inductor 11 A is valid. For enhancing the efficiency, the inductance value of the inductor 11 A is greater than the inductance values of the other inductors 11 B- 11 D, and, thus the power loss induced by the ACR value of the inductor 11 A is decreased. When the loading current IL is smaller than the threshold VTH 1 , the inductor 11 A having greater inductance value is valid for enhancing the efficiency. When the loading current IL is larger than the threshold VTH 1 , most of the inductors 11 A- 11 D (excluding the inductor 11 A) have less inductance values, and, thus, the power loss induced by the DCR values of the inductors is decreased, thereby enhancing the efficiency. In this case, since at least two inductors are valid, the loading current IL obtained from the inductor current flowing through the at least two inductors is sufficient for the loading.

FIG. 3 shows an exemplary embodiment of a curve of relationship between the efficiency and the loading current IL. As shown in FIG. 3 , through the unbalanced inductance values of the inductors 11 A- 11 D, the voltage supply circuit 1 has enhanced efficiency at the mode M 20 -M 23 .

FIG. 4 shows an exemplary embodiment of a controlling method. In the following, the controlling method will be described by referring to FIGS. 1, 2, and 4 . First, the loading state of the voltage supply circuit 1 is obtained by determining the loading current IL (step S 40 ). When it is determined that the loading current IL is smaller than the threshold VTH 1 , the voltage supply circuit 1 enters the first mode M 20 , and the voltage supply circuit 1 is controlled to only enable the driver circuit 10 A to generate a driving voltage V 10 A for the inductor 11 A having the inductance value greater than other inductors 11 B- 11 D (step S 41 ). When it is determined that the loading current IL is smaller than the threshold VTH 2 and larger than the threshold VTH 1 , the voltage supply circuit 1 enters the second mode M 21 , and the voltage supply circuit 1 is controlled to enable the driver circuits 10 A and 10 B to generate driving voltages V 10 A and V 10 B to the inductors 11 A and 11 B respectively (step S 42 ).

When it is determined that the loading current IL is smaller than the threshold VTH 3 and larger than the threshold VTH 2 , the voltage supply circuit 1 enters the third mode M 22 , and the voltage supply circuit 1 is controlled to enable the driver circuits 10 A- 10 V to generate driving voltages V 10 A-V 10 C for the inductors 11 A- 11 C respectively (step S 43 ). When it is determined that the loading current IL is larger than the threshold VTH 3 , the voltage supply circuit 1 enters the fourth mode M 23 , and the voltage supply circuit 1 is controlled to enable all of the driver circuits 10 A- 10 D to generate driving voltages V 10 A-V 10 D to the inductors 11 A- 11 D respectively (step S 44 ).

According to the embodiment of the controlling method, when the loading of the voltage supply circuit 1 is less, the inductor which has the greater inductance value is valid, which can decrease power loss and thus enhance efficiency of the voltage supply circuit 1 due to decrement of the power loss induced by the ACR value. When the loading of the voltage supply circuit 1 current IL is greater, most of the valid inductors have less inductance values, which can decrease power loss and thus enhance efficiency of the voltage supply circuit 1 due to decrement of the power loss induced by the DCR values of the valid inductors. Thus, the voltage supply circuit 1 has better efficiency at each of the modes M 20 -M 23 .

While the invention has been described by way of example and in terms of the preferred embodiments, it is to be understood that the invention is not limited to the disclosed embodiments. To the contrary, it is intended to cover various modifications and similar arrangements (as would be apparent to those skilled in the art). Therefore, the scope of the appended claims should be accorded the broadest interpretation so as to encompass all such modifications and similar arrangements.