GB2514642A

GB2514642A - Regulator, converter and controlling method

Info

Publication number: GB2514642A
Application number: GB1403157.9A
Authority: GB
Inventors: Quentin Lin; Egbert Mao; David Wang
Original assignee: Tridonic GmbH and Co KG
Current assignee: Tridonic GmbH and Co KG
Priority date: 2013-04-28
Filing date: 2014-02-21
Publication date: 2014-12-03
Also published as: GB201403157D0; WO2014176721A1

Abstract

A regulator comprises a converter 101 and a controlling unit 102. The converter is preferably a buck converter. The controlling unit is configured to adjust the input voltage Vbus according to the output voltage Vled, so as to keep the difference of the input voltage and the output voltage constant or approximately constant. The regulator may comprise a switch 201, an inductor 202, a rectifier diode 203 and a capacitor 204. The switch may be a FET. The load may be an LED. The object of the invention is to keep the on-time of switch constant or approximately constant even though the load is variable.

Description

REGULATOR, CONVERTER AND

CONTROLLING METHOD

FIELD OF THE INVENTION

This application relates to electrical converter, and in particular to a regulator, a converter and a controlling method.

BACKGROUND

Nowadays, modem LED (Light Emitting Diode) driver always use regulator or buck converter to get constant current. Figure 1 is a block diagram of a buck converter according to the prior art.

As shown in Figure 1, the buck converter is used to generate an output voltage (Vied) from an input voltage (VbUS). There are a switch (for example, an n-channel field-effect transistor), an inductor, a diode and a capacitor.

The on-time of the switch can be controlled by controlling the difference 0** between the Vb, and Vied.

However, the applicant found that: In such type of device, the difference : * : : : between VbUS and Vi may be too high when load (external device, such as LED) is changed in some scenario. The on-time of the switch will be : reduced, and the reduced on-time will lose efficiency. ** * * * * * **

SUMMARY

Embodiments of the present invention pertain to a regulator, a buck converter and a controlling method. The objection of the invention is to keep the on-time of switch constant or approximately constant even though the load is variable.

According to a first aspect of the embodiments of the present invention, there is provided a regulator for generating an output voltage (Vied) from an input voltage (VbU), includes: a converter, a converter, preferably a buck converter, configured to generate the output voltage (V1) by using the input voltage (Vbj; a controlling unit, configured to adjust the input voltage (Vb) according to the output voltage (V1), so as to keep the difference of the input voltage (Vb3) and the output voltage (Vied) constant or approximately constant.

According to another aspect of the embodiments of the present invention, wherein the converter includes: a switch, which comprises a first terminal and a second terminal; wherein the switch is turned ON or OFF depending on the voltage level of the input voltage (VbS) and the output voltage (V1); an inductor, which comprises a third terminal and a fourth terminal; wherein the third terminal is electrically connected with the second terminal; a rectifier, which comprises a fifth terminal and a sixth terminal; wherein the fifth terminal is electrically connected with the second terminal; a capacitor, which comprises a seventh terminal and a eighth terminal; wherein the seventh terminal is electrically connected with the fourth terminal, is and the eighth terminal is electrically connected with the sixth terminal.

According to another aspect of the embodiments of the present invention, wherein the first terminal is electrically coupled with the negative of the input * voltage (VbUJ; and, the eighth terminal and the sixth terminal is electrically coupled with the positive of the input voltage (VbUj.

:.::, 20 According to another aspect of the embodiments of the present invention, wherein the rectifier is a diode; and the fifth terminal comprises an anode of * the diode, arid the sixth terminal comprises a cathode of the diode.

:.: According to another aspect of the embodiments of the present invention, wherein the first terminal is electrically coupled with the positive of the input voltage (Vb11j; and, the eighth terminal and the sixth terminal is electrically coupled with the negative of the input voltage (Vbj.

According to another aspect of the embodiments of the present invention, wherein the rectifier is a diode; and the fifth terminal comprises a cathode of the diode, and the sixth terminal comprises an anode of the diode.

According to another aspect of the embodiments of the present invention, wherein the switch is an n-channel field-effect transistor, or a p-channel

field-effect transistor.

According to a second aspect of the embodiments of the present invention, there is provides a converter for generating an output voltage (VIed) from an input voltage (VbUJ, includes: a switch, which comprises a first terminal and a second terminal; wherein the switch is turned ON or OFF depending on the voltage level of the input voltage (VbUS) and the output voltage (Vied); an inductor, which comprises a third terminal and a fourth terminal; wherein the third terminal is electrically connected with the second terminal; a rectifier, which comprises a fifth terminal and a sixth terminal; wherein the fifth terminal is electrically connected with the second terminal; a capacitor, which comprises a seventh terminal and a eighth terminal; wherein the seventh terminal is electrically connected with the fourth terminal, and the eighth terminal is electrically connected with the sixth terminal; a controller, which is used to adjust the input voltage (Vb) according to the output voltage (Vied), so as to keep the difference of the input voltage (Vb) and the output voltage (Vied) constant or approximately constant.

Is According to another aspect of the embodiments of the present invention, wherein the first terminal is electrically coupled with the negative of the input voltage (Vbj; and the eighth terminal and the sixth terminal is electrically * coupled with the positive of the input voltage (Vb).

According to another aspect of the embodiments of the present invention, :,:: 20 wherein the rectifier is a diode; and the fifth terminal comprises an anode of the diode, and the sixth terminal comprises a cathode of the diode.

* According to another aspect of the embodiments of the present invention, :..: wherein the switch is an n-channel field-effect transistor, or a p-channel

* * field-effect transistor.

According to a third aspect of the embodiments of the present invention, there is provides a controlling method, applied in a regulator or a converter for generating an output voltage (Vied) from an input voltage (Vb), the method includes: detecting the output voltage (Vied), wherein the output voltage (Vied) is variable for different external devices; adjusting the input voltage (Vb) according to the output voltage (Vied), so as to keep the difference of the input voltage (Vb5) and the output voltage (Vied) constant or approximately constant.

According to a fourth aspect of the embodiments of the present invention, there is provides a computer-readable program, wherein when the program is executed in a regulator or a converter, the program enables the computer to carry out the controlling method.

According to a fifth aspect of the embodiments of the present invention, s there is provides a storage medium in which a computer-readable program is stored, wherein the computer-readable program enables the computer to carry out the controlling method.

The advantages of the present invention exist in that: the difference of the input voltage (Vb) and the output voltage (Viea) is constant or approximately constant by using the controlling unit. The on-time of the switch will be constant or approximately constant even though the load is variable, and the efficiency can be improved.

These and further aspects and features of the present invention will be apparent with reference to the following description and attached drawings. In the description and drawings, particular embodiments of the invention have been disclosed in detail as being indicative of some of the ways in which the principles of the invention may be employed, but it is understood that the invention is not limited correspondingly in scope. Rather, the invention *.....

* includes all changes, modifications and equivalents coming within the spirit :.:.. 20 and terms of the appended claims.

Features that are described and/or illustrated with respect to one : embodiment may be used in the same way orin a similar way in one or more other embodiments and/or m combination with or instead of the features of * the other embodiments.

It should be emphasized that the term "comprises/comprising" when used in this specification is taken to specify the presence of stated features, integers, steps or components but does not preclude the presence or addition of one or more other features, integers, steps, components or groups thereof.

Many aspects of the invention can be better understood with reference to the following drawings. The components in the drawings are not necessarily to scale, emphasis instead being placed upon clearly illustrating the principles of the present invention. To facilitate illustrating and describing some parts of the invention, corresponding portions of the drawings may be exaggerated in size, e.g., made larger in relation to other parts than in an exemplary device actually made according to the invention. Elements and features depicted in one thawing or embodiment of the invention may be combined with elements and features depicted in one or more additional drawings or embodiments.

Moreover, in the drawiiigs, like reference numerals designate corresponding s parts throughout the several views and may be used to designate like or similar parts in more than one embodiment.

BRThF DESCRIPTION OF THE DRAWING

The drawings are included to provide ftirther understanding of the present invention, which constitute a part of the specification and illustrate the preferred embodiments of the present invention, and are used for setting forth the principles of the present invention together with the description. The same element is represented with the same reference number throughout the drawings.

is In the drawings: Figure 1 is a block diagram of a buck converter according to the prior * r Figure 2 is a schematic diagram of the regulator in accordance with an * *. embodiment of the present invention; ** . Figure 3 is another schematic diagram of the regulator in accordance with an embodiment of the present invention; Figure 4 is another schematic diagram of the regulator in accordance with an embodiment of the present invention; Figure 5 is a schematic diagram of the converter in accordance with an embodiment of the present invention; Figure 6 is a flowchart of the controlling method in accordance with an embodiment of the present invention.

DETAILED DESCRIPTION

The many features and advantages of the embodiments are apparent from the detailed specification and, thus, it is intended by the appended claims to cover all such features and advantages of the embodiments that fall within the true spirit and scope thereof Further, since numerous modifications and changes will readily occur to those skilled in the art, it is not desired to limit the inventive embodiments to the exact construction and operation illustrated and described, and accordingly all suitable modifications and equivalents may be resorted to, falling within the scope thereof As shown in Figure 1, the on-time (t0) of the switch can be calculated by the following formula: t -2'L*Ild on Vbus Vied As shown in this formula, the on-time of the switch is related to the difference of the Vb and Vied. Vied may be changed if the load is changed, that is to say, for variable led load, Vied is variable.

On the other hand, reduced on-time of the switch has the following consequences: increased conduction losses; increased RMS current trough the switch. There are terminals to connect LED (may be called V+ and V-). Take 20W as example, output current of buck stage changes from 350mA to 900mA, output voltage will change from 57V to 22V, so if the same input voltage is kept, the more output current is, the bigger voltage gap will be *fl...

* between input and output.

: *. So in this invention, V1 is detected to control bus voltage and the on-time of the switch. The preferred embodiments of the present invention are : 20 described as follows in reference to the drawings. 0S S

Embodiment 1 This embodiment of the present invention provides a regulator for generating an output voltage (Vied) from an input voltage (VbUS). Figure 2 is a schematic diagram of the regulator in accordance with an embodiment of the present invention.

As shown in Figure 2, the regulator 100 includes: a buck converter 101 and a controlling unit 102. Other parts of the regulator 100 can refer to the existing technology and not be described in the present application.

Where, the buck converter 101 is configured to generate the output voltage (Vtea) by using the input voltage (Vb); the controlling unit 102 is configured to adjust the input voltage (Vb5) according to the output voltage (Vied), so as to keep the difference of the input voltage (VbUS) and the output voltage (Vied) constant or approximately constant.

In this embodiment, in LED driver application, the load may be LED.

One LED can be seen as a constant voltage cell, and Vied may be different for different load.

In this embodiment, the difference of the input voltage (VbUS) and the output voltage (Viea) is constant or approximately constant by using the controlling unit 102. The on-time of the switch will be constant or approximately constant even though the load is variable.

In an implement way, compared with the buck converter shown in Figure 1, the structure of the buck converter 101 will be changed. Figure 3 is another schematic diagram of the regulator in accordance with an embodiment of the present invention.

As shown in Figure 3, the buck converter 101 may include: a switch 201, Is an inductor 202, a rectifier 203 and a capacitor 204.

Wherein, the switch 201 has a first terminal 2011 and a second terminal 2012; the switch 201 is turned ON or OFF depending on the voltage level of the input voltage (Vb) and the output voltage (Vied); the inductor 202 has a third terminal 2021 and a fourth terminal 2022; a...

* 20 wherein the third terminal 2021 is electrically connected with the second terminal 2012; the rectifier 203 has a fifth terminal 2031 and a sixth terminal 2032; wherein the fifth terminal 2031 is electrically connected with the second terminal 2012; :.: * 25 the capacitor 204 has a seventh terminal 2041 and a eighth terminal 2042; *. *. wherein the seventh terminal 2041 is electrically connected with the fourth terminal 2022, and the eighth terminal 2042 is electrically connected with the sixth terminal 2032.

As shown in Figure 3, the first terminal 2011 is electrically coupled with the negative of the input voltage (Vbj; and, the eighth terminal 2042 and the sixth terminal 2032 is electrically coupled with the positive of the input voltage (Vbu).

In implement, the rectifier (203) may be a diode; and the fifth terminal 2031 includes an anode of the diode, and the sixth terminal 2032 includes a cathode of the diode.

Furthermore, the switch 201 may be an n-channel field-effect transistor, a p-channel field-effect transistor, a NPN bipolar transistor or may be PNP bipolar transistor. However it is not limited thereto, and particular implement entity may be determined as actually required.

In this implement way, the on-time of the switch is defined by the voltage of (Vbur Vied). As shown in Figure 3, the voltage of (VhU5-Vied) is equal to the voltage of V1. So the voltage of Vled can be used to control V. When V1 (equal to VbUS-Vied) is constant, the on-time of the switch is constant even if the load is variable according to the formula: t -2*L*Iied on 1/ bus Vied In this embodiment, buck efficiency may be improved by detecting Vied.

and setting Vbus, so as to keep the on-time of the switch constant in LED driver application. The setting of Vb may also depend on the led, as led may be selected by the user, e.g. by a DIP-switch, and such as from 3SOmA to lO5OmA.

The input voltage Vb may be provided by a pre-regulator which may * form a part of the regulator 100. The pre-regulator may be preferably an *". 20 isolated switched converter, e.g. a flyback converter or an isolated resonant halfbridge convertet The pre-regulator may adjust its pre-regulator output voltage which represents the input voltage Vb for the regulator, e.g. the buck ::: :: converter. If the pre-regulator is formed by an isolated switched converter it may cross a potential isolation barrier which enables the converter to be a SELY equivalent converter and which comprises a potential isolation barrier which increases the protection of the converter as it lowers the risk of accidental contact with a higher voltage fir the user. A SELV equivalent converter is an electrical converter in which the voltage cannot exceed extra-low voltage under normal conditions, and under single-fault conditions, including earth faults in other circuits. The potential isolation barrier provides protective isolation.

B

Preferably the adjustment of the input voltage Ybus is performed by a isolated feedback path from the the controlling unit 102 over the potential isolation barrier which is crossed by the pre-regulator. Such isolated feedback path over the potential isolation barrier may be formed by a feedback circuit including an optocoupler crossing the potential isolation barrier. The pre-regulator may adjust the voltage provided at its output according to the feedback of adjustment of input voltage bus by the controlling unit 102. The pre-regulator may comprise at least one clocked switch. This clocked switch may be controlled by a control unit. The control unit may alter the frequency and / or duty cycle at which the clocked switch of the pre-regulator is clocked in order to adjust the input voltage VbU5 for the buck converter 101.

In another implement way, compared with the buck converter shown in Figure 1, the structure of the buck converter 101 will not be changed. Figure 4 is another schematic diagram of the regulator in accordance with an embodiment of the present invention.

As shown in Figure 4, the buck converter 101 may include: a switch 201, an inductor 202, a rectifier 203 and a capacitor 204.

Wherein, the switch 201 has a first terminal 2011 and a second terminal 2012; the switch 201 is turned ON or OFF depending on the voltage level of the input voltage (VbU5) and the output voltage (Vi); : .:: :* the inductor 202 has a third terminal 2021 and a fourth terminal 2022; wherein the third terminal 2021 is electrically connected with the second terminal 2012; the rectifier 203 has a fifth terminal 2031 and a sixth terminal 2032; wherein the fifth terminal 2031 is electrically connected with the second terminal 2012; the capacitor 204 has a seventh terminal 2041 and a eighth terminal 2042; wherein the seventh terminal 2041 is electrically connected with the fourth terminal 2022, and the eighth terminal 2042 is electrically connected with the sixth terminal 2032.

As shown in Figure 4, the first terminal 2011 is electrically coupled with the positive of the input voltage (Vbj; and, the eighth terminal 2042 and the sixth terminal 2032 is electrically coupled with the negative of the input voltage (VbUS).

In implement, the rectifier 203 is a diode; and the fifth terminal 2031 includes a cathode of the diode, and the sixth terminal 2032 includes an anode of the diode.

s Furthermore, the switch 201 may be an n-channel field-effect transistor, or may be a p-channel field-effect transistor. However it is not limited thereto, and particular implement entity may be determined as actually required.

Furthermore, the switch 201 may be alternatively arranged on high potential at the input of the converter as well, meaning that the switch 201 can be coupled to the first terminal 2011 which is electrically coupled with the positive of the input voltage (VbUj.

It can be seen from the above embodiment that: the difference of the input voltage (VbS) and the output voltage (Vjd) is constant or approximately constant by using the controlling unit. The on-time of the switch will be Is constant or approximately constant even though the load is variable, and the efficiency may be improved.

Embodiment 2 r * This embodiment of the present invention provides a buck converter for generating an output voltage (Vied) from an input voltage (Vbuj. This embodiment is based on the embodiment 1 and the same content will not be described.

Figure 5 is a schematic diagram of the buck converter in accordance * ** with an embodiment of the present invention.

: 25 As shown in Figure 5, the buck converter 300 includes: a switch 301, an . .: inductor 302, a rectifier 303, a capacitor 304 and a controller 305.

Wherein, the switch 301 has a first terminal 3011 and a second terminal 3012; the switch 301 is turned ON or OFF depending on the voltage level of the input voltage (Vb5) and the output voltage (Vied); the inductor 302 has a third terminal 3021 and a fourth terminal 3022; wherein the third terminal 3021 is electrically connected with the second terminal 3012; the rectifier 303 has a fifth terminal 3031 and a sixth terminal 3032; wherein the fifth terminal 3031 is electrically connected with the second terminal 3012; the capacitor 304 has a seventh terminal 3041 and a eighth terminal 3042; wherein the seventh terminal 3041 is electrically connected with the fourth terminal 3022, and the eighth terminal 3042 is electrically connected with the sixth terminal 3032; the controller 305 is used to adjust the input voltage (VbUS) according to the output voltage (Vied), so as to keep the difference of the input voltage (Vb) and the output voltage (Vied) constant or approximately constant.

As shown in Figure 5, the first terminal 3011 is electrically coupled with the negative of the input voltage (Vb); and, the eighth terminal 3042 and the sixth terminal 3032 is electrically coupled with the positive of the input voltage (VbUJ.

In implement, the rectifier 303 is a diode; and the fifth terminal 3031 includes an anode of the diode, and the sixth terminal 3032 includes a cathode of the diode.

In implement, the switch 301 is an n-channel field-effect transistor, or a p-channel field-effect transistor. However it is not limited thereto, and particular implement entity may be determined as actually required.

It can be seen from the above embodiment that: the difference of the input voltage (VbUS) and the output voltage (V1) is constant or approximately constant by using the controller. The on-time of the switch : will be constant or approximately constant even though the load is variable, and the efficiency may be improved. * *. * * *

Embodiment 3 ** * * This embodiment of the present invention provides a controlling method, applied in a regulator 100 or a buck converter 300 for generating an output voltage (Vied) from an input voltage (Vb). This embodiment is based on the embodiment 1 or 2, and the same content will not be described.

Figure 6 is a flowchart of the controlling method in accordance with an embodiment of the present invention. As shown in. Figure 6, the method includes: Step 601, detecting the output voltage (Vied), wherein the output voltage (V1d) is variable for different external devices; Step 602, adjusting the input voltage (VbUS) according to the output voltage (Vied), so as to keep the difference of the input voltage (VbUS) and the output voltage (Vied) constant or approximately constant.

It can be seen from the above embodiment that: the difference of the input voltage (VbU) and the output voltage (V1) is constant or approximately constant, by detecting the output voltage and adjusting the input voltage. The on-time of the switch will be constant or approximately constant even though the load is variable, and the efficiency may be improved.

The invention is not limited to a buck converter. As an alternative embodiment the regulator may be formed by another type of switch mode converter, e.g. by a boost converter or a buck-boost converter. The buck converter is only one example which has been explained as one variant of a regulator in detail.

This embodiment of the present invention also provides a computer-readable program, wherein when the program is executed in a regulator or a buck converter, the program enables the computer to carry out the controlling method.

* This embodiment of the present invention also provides a storage medium in which a computer-readable program is stored, wherein the computer-readable program enables the computer to carry out the controlling * * method in a regulator or a buck converter.

The description or blocks in the flowcharts or of any process or method in other manners may be understood as being indicative of comprising one or more modules, segments or parts for realizing the codes of executable instructions of the steps in specific logic functions or processes, and that the scope of the preferred embodiments of the present invention comprise other implementations, wherein the functions may be executed in manners different from those shown or discussed, including executing the functions according to the related functions in a substantially simultaneous manner or in a reverse order, which should be understood by those skilled in the art to which the present invention pertains.

The logic andlor steps shown in the flowcharts or described in other manners here may be, for example, understood as a sequencing list of executable instructions for realizing logic functions, which may be implemented in any computer readable medium, for use by an instruction executing system, device or apparatus (such as a system including a computer, a system including a processor, or other systems capable of extracting instructions from an instruction executing system, device or apparatus and executing the instructions), or for use in combination with the instruction executing system, device or apparatus.

The above literal description and drawings show various features of the present invention. It should be understood that those skilled in the art may prepare appropriate computer codes to carry out each of the steps and processes as described above and shown in the drawings. It should be also understood that all the terminals, computers, servers, and networks may be Is any type, and the computer codes may be prepared according to the diclosure to carry out the present invention by using the apparatus.

Particular embodiments of the present invention have been disclosed herein. Those skilled in the art will readily recognize that the present *r invention is applicable in other environments. In practice, there exist many embodiments and implementations. The appended claims are by no means 0***** * intended to limit the scope of the present invention to the above particular embodiments. Furthermore, any reference to "a device to..." is an explanation of device plus function for describing elements and claims, and it is not * ** desired that any element using no reference to "a device to..." is understood as an element of device plus function, even though the wording of "device" is * included in that claim.

Although a particular preferred embodiment or embodiments have been shown and the present invention has been described, it is obvious that equivalent modifications and variants are conceivable to those skilled in the art in reading and understanding the description and drawings. Especially for various functions executed by the above elements (portions, assemblies, apparatus, and compositions, etc.), except otherwise specified, it is desirable that the terms (including the reference to "device") describing these elements correspond to any element executing particular fUnctions of these elements (i.e. functional equivalents), even though the element is different from that executing the function of an exemplary embodiment or embodiments illustrated in the present invention with respect to structure. Furthermore, although the a particular feature of the present invention is described with s respect to only one or more of the illustrated embodiments, such a feature may be combined with one or more other features of other embodiments as desired and in consideration of advantageous aspects of any given or particular application. * . * ** * * * * ** * * * *** * S. * S S * S 55

Claims

CLAIMS1. A regulator (100) for generating an output voltage (V1) from an input voltage (Vbj, comprising: a converter (101), preferably a buck converter, configured to generate the output voltage (Vld) by using the input voltage (VbUS); a controlling unit (102), configured to adjust the input voltage (VbUS) according to the output voltage (V11), so as to keep the difference of the input voltage (Vb) and the output voltage (Vied) constant or approximately constant.
2. The regulator (100) according to claim 1, wherein the converter (101) comprising: a switch (201), which comprises a first terminal (2011) and a second terminal (2012); wherein the switch (201) is turned ON or OFF depending on the voltage level of the input voltage (VbUS) and the output voltage (V1); an inductor (202), which comprises a third terminal (2021) and a fourth terminal (2022); wherein the third terminal (2021) is electrically connected with the second terminal (2012); a rectifier (203), which comprises a fifth terminal (2031) and a sixth : *.* terminal (2032); wherein the fifth terminal (2031) is electrically connected fl with the second terminal (2012); a capacitor (204), which comprises a seventh terminal (2041) and a eighth terminal (2042); wherein the seventh terminal (2041) is electrically * 25 connected with the fourth terminal (2022), and the eighth terminal (2042) is electrically connected with the sixth terminal (2032).
3. The regulator (100) according to claim 2, wherein the first terminal (2011) is electrically coupled with the negative of the input voltage (Vb); and the eighth terminal (2042) arid the sixth terminal (2032) is electrically coupled with the positive of the input voltage (Vbj.
4. The regulator (100) according to claim 3, wherein the rectifier (203) is a diode; and the fifth tenninal (2031) comprises an anode of the diode, and the sixth terminal (2032) comprises a cathode of the diode.
5. The regulator (100) according to claim 2, wherein the first terminal (2011) is electrically coupled with the positive of the input voltage (VbUJ; and the eighth terminal (2042) and the sixth terminal (2032) is electrically coupled with the negative of the input voltage (Vb8).
6. The regulator (100) according to claim 5, wherein the rectifier (203) is a diode; and the fifth terminal (2031) comprises a cathode of the diode, and the sixth terminal (2032) comprises an anode of the diode.
7. The regulator (100) according to any of claim 2-6, wherein the switch (201) is an n-channel field-effect transistor, or a p-channel field-effect transistor. I... * 20

*
8. A converter (300), preferably a buck converter, for generating an output voltage (Vld) from an input voltage (VbUJ, comprising: a switch (301), which comprises a first terminal (3011) and a second * ** terminal (3012); wherein the switch (301) is turned ON or OFF depending on :.: 25 the voltage level of the input voltage (VbU3) and the output voltage (V1); * an inductor (302), which comprises a third terminal (3021) and a fourth terminal (3022); wherein the third terminal (3021) is electrically connected with the second terminal (3012); a rectifier (303), which comprises a fifth terminal (3031) and a sixth terminal (3032); wherein the fifth terminal (3031) is electrically connected with the second terminal (3012); a capacitor (304), which comprises a seventh terminal (3041) and a eighth terminal (3042); wherein the seventh terminal (3041) is electrically connected with the fourth terminal (3022), and the eighth terminal (3042) is electrically connected with the sixth terminal (3032); a controller (305), which is used to adjust the input voltage (VbUS) according to the output voltage (Vied), so as to keep the difference of the input voltage (VbUS) and the output voltage (Vied) constant or approximately constant.
9. The converter (300) according to claim 8, wherein the first terminal (3011) is electrically coupled with the negative of the input voltage (Vbj; and the eighth terminal (3042) and the sixth terminal (3032) is electrically coupled with the positive of the input voltage (VbUS).
10. The converter (300) according to claim 9, wherein the rectifier (303) is a diode; and the fifth terminal (3031) comprises an anode of the diode, and the sixth is terminal (3032) comprises a cathode of the diode.
11. The converter (300) according to any of claim 8-10, wherein the switch (301) is an n-channel field-effect transistor, or a p-channel field-effect transistor. * 20

*
12. A controlling method, applied in a regulator (100) or a converter :.:::. (300) for generating an output voltage (Vied) from an input voltage (VbUS), the method comprising: : ***. detecting the output voltage (Vied), wherein the output voltage (VIed) is :: 25 vanable for different external devices; adjusting the input voltage (VbUS) according to the output voltage (Vied), so as to keep the difference of the input voltage (V55) and the output voltage (V1) constant or approximately constant.
13. A computer-readable program, wherein when the program is executed in a regulator or a converter, the program enables the computer to carry out the controlling method as claimed in claim 12 in the regulator or the buck converter.
14. A storage medium in which a computer-readable program is stored, wherein the computer-readable program enables the computer to carry out the s controlling method as claimed in claim 12 in a regulator or a converter. o*e * * * *. * . * * ** * . * *.* * * * * * * * SI