# Patent

## Title
Programmable power supply

## Abstract

The present invention provides a method of programming a programmable power supply. In the method, a requesting signal is generated in a device, and the requesting signal is received in the programmable power supply. Then, an output voltage of the programmable power supply is determined in accordance with a frequency of the requesting signal. The output voltage of the programmable power supply is coupled to power a load of the device. A de-bounce operation is further provided for filtering noises of the requesting signal. The requesting signal comprises a high-state period and a low-state period. The high-state period is defined during which a level of the requesting signal is higher than a threshold. The low-state period is defined during which the level of the requesting signal is lower than the threshold. The output voltage of the programmable power supply is further determined by a period of the requesting signal.

## Background
CROSS REFERENCE TO RELATED APPLICATIONS
This application claims the benefit of U.S. Provisional Application No. 61/804,430, filed on Mar. 22, 2013, the contents of which are incorporated herein by reference.


BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a programmable power supply; more specifically, the present invention relates to a method of programming a programmable power supply.
2. Description of the Related Art
Manufacturers of today's power supplies for mobile devices, such as notebooks, cellular phones, and tablet computers, provide various designs to supply those mobile devices with different supply voltages. Therefore, users with multiple mobile devices are often required to carry all of those power supplies for providing power to each individual mobile device, which becomes a burden for the users who often carry those mobile devices with them. In order to reduce such burdens, power supplies manufacturers have developed a programmable power supply capable of supplying different voltages on the demand of the mobile devices. Communication between the programmable power supplies and the mobile devices to guarantee safe and stable voltage switching becomes a major concern.
BRIEF SUMMARY OF THE INVENTION
The objective of the present invention is to providing a method of programming a programmable power supply to power the mobile device on its demand.
The present invention provides a method of programming a programmable power supply. The method comprises: generating a requesting signal in a device; receiving the requesting signal in the programmable power supply; and determining an output voltage of the programmable power supply in accordance with a frequency of the requesting signal. The output voltage of the programmable power supply is coupled to power a load of the device. The method further comprises providing a de-bounce operation for filtering noises of the requesting signal. The requesting signal comprises a high-state period and a low-state period. The high-state period is defined during which a level of the requesting signal is higher than a threshold. The low-state period is defined during which the level of the requesting signal is lower than the threshold. The output voltage of the programmable power supply is further determined by the high-state period of the requesting signal. The output voltage of the programmable power supply is further determined by the low-state period of the requesting signal. The output voltage of the programmable power supply is further determined by a period of the requesting signal.
The present invention also provides a method of programming a programmable power supply. The method comprises: generating a requesting signal in a device; receiving the requesting signal in the programmable power supply; detecting a high-state period of the requesting signal; detecting a low-state period of the requesting signal; checking whether the high-state period of the requesting signal meets a first boundary condition; checking whether the low-state period of the requesting signal meets a second boundary condition; and determining an output voltage of the programmable power supply in accordance with a result of the checking step of the high-state period and a result of the checking step of the low-state period. The output voltage of the programmable power supply is coupled to power a load of the device. The method further comprises providing a de-bounce operation for filtering noises of the requesting signal. The high-state period is defined during which a level of the requesting signal is higher than a threshold. The low-state period is defined during which the level of the requesting signal is lower than the threshold. The step of determining the output voltage of the programmable power supply comprises: generating a count in accordance with the result of the checking step of the high-state period and the result of the checking step of the low-state period; and determining the output voltage of the programmable power supply in accordance with a value of the count. When the high-state period of the requesting signal meets the first boundary condition and the low-state period of the requesting signal meets the second boundary condition, the value of the count is increased. When the high-state period of the requesting signal fails to meet the first boundary condition or the low-state period of the requesting signal fails to meet the second boundary condition, the value of the count is decreased.
The present invention further provides a method of programming a programmable power supply. The method comprises: generating a requesting signal in a device; detecting the requesting signal in the programmable power supply; and determining an output voltage of the programmable power supply in accordance with a ratio combination of a high-state period and a low-state period of the requesting signal. The output voltage of the programmable power supply is coupled to power a load of the device. The method further comprises providing a de-bounce operation for filtering noises of the requesting signal. The high-state period is defined during which a level of the requesting signal is higher than a threshold, and the low-state period is defined during which the level of the requesting signal is lower than the threshold. The ratio combination comprises a percentage of a period of the requesting signal being occupied by the high-state period and another percentage of the period of the requesting signal being occupied by the low-state period.
A detailed description is given in the following embodiments with reference to the accompanying drawings.



BRIEF DESCRIPTION OF THE 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 a schematic of a system for programming a programmable power supply according to the present invention;
FIG. 2 shows a waveform of a requesting signal according to the present invention;
FIG. 3 shows an embodiment of a control flow of a detector according to the present invention;
FIG. 4 shows a control flow of a requesting-signal detection block of the detector according to the present invention;
FIG. 5 shows a control flow of a checking block of the requesting-signal detection block according to the present invention;
FIG. 6 shows another aspect of the control flow in FIG. 3 according to the present invention;
FIG. 7A shows an example of a cross-reference table of a high-state period, a low-state period, and an output voltage; and
FIG. 7B shows an example of a cross-reference table of a frequency of the requesting signal and the output voltage.



DETAILED DESCRIPTION OF THE INVENTION
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.
FIG. 1 shows a schematic of a system for programming a programmable power supply according to the present invention. A programmable power supply 10 includes a programmable voltage source 25 and a detector 100. The programmable voltage source 25 will provide an output voltage VCC coupled to power a load 30 of a device 20. The device 20 includes the load 30 and a signal generation circuit 300. In one embodiment of the present invention, the signal generation circuit 300 can be an application processor. Yet in another embodiment of the present invention, the signal generation circuit 300 can be a waveform generation circuit. The signal generation circuit 300 will generate a requesting signal VS to program the output voltage VCC in response to an energy demand of the load 30. The requesting signal VS may go from the device 20 to the detector 100 of the programmable power supply 10 via, for example, a D-wire of an USB (Universal Serial Bus) cable. The detector 100 controls the programmable voltage source 25 for generating the output voltage VCC in response to the requesting signal VS. The output voltage VCC is programmed to a demanded level, such as 5V, 9V, 12V, 18V, etc, on the energy demand of the load 30.
FIG. 2 shows the waveform of the requesting signal VS according to the present invention. The requesting signal VS has a high-state if the level of the requesting signal VS is higher than a threshold VT. The requesting signal VS has a low-state if the level of the requesting signal VS is lower than the threshold VT. TH represents a high-state period of the requesting signal VS. TL represents a low-state period of the requesting signal VS. T represents a period of the requesting signal VS, which is the reciprocal of the frequency of the requesting signal VS. The period T is also correlated to the high-state period TH and the low-state period TL. A period T1 defines a low-period-threshold for the high-state period TH. A period T2 defines a high-period-threshold for the high-state period TH. A period T3 defines a low-period-threshold for the low-state period TL. A period T4 defines a high-period-threshold for the low-state period TL. The periods T1 and T2 define a first boundary condition (criterion) for the high-state period TH. The periods T3 and T4 define a second boundary condition (criterion) for the low-state period TL. Each pair of the high-state period TH and the low-state period TL will define one corresponding level of the output voltage VCC. It is to be understood that the requesting signal VS can be in any waveform which alternately crosses at least one threshold, such as square wave, triangle wave, sinusoidal wave, etc.
FIG. 3 shows an embodiment of a control flow of the detector 100 according to the present invention. The detector 100 is used to detect the high-state period TH and the low-state period TL of the requesting signal VS for determining the level of the output voltage VCC that is demanded by the load 30. If the high-state period TH and the low-state period TL of the requesting signal VS meet the boundary conditions (criteria) as aforementioned, the detector 100 will control the programmable voltage source 25 to set a corresponding level of the output voltage VCC to power the load 30 of the device 20.
At the beginning of the control flow, the output voltage VCC is set as an initial voltage level V0, e.g. 5V. A parameter setting block 110 will next set periods (parameters) T1, T2, T3 and T4. A requesting-signal detection block 150 will detect the high-state period TH and the low-state period TL of the requesting signal VS in reference with the periods T1, T2, T3, and T4 to generate a count N. If the high-state period TH and the low-state period TL of the requesting signal VS meet the criteria set by the parameters T1, T2, T3, and T4, the requesting-signal detection block 150 will increase a value of the count N by one (N=N+1). If the boundary conditions are met for more than M cycles, the value of the count N will be set as M (N=M). Once the value of the count N is equal to M, the output voltage VCC will be set as a voltage V1, e.g. 6V.
If the high-state period TH and the low-state period TL of the requesting signal VS don't meet the boundary conditions set by the parameters T1, T2, T3, and T4, the requesting-signal detection block 150 will decrease the value of the count N by one (N=N−1). If the value of the count N is equal to zero (N=0), the output voltage VCC will be set as the initial voltage level V0.
Therefore, the output voltage VCC can be set as any desired values (V0, V1, . . . , or VN) according to the detected high-state period TH and the low-state period TL of the requesting signal VS. Since the period T of the requesting signal VS is correlated to the high-state period TH and the low-state period TL, it can be understood that in another embodiment, the output voltage VCC can be set as any desired values according to the period T (or the frequency) of the requesting signal VS. In the requesting-signal detection block 150, a noise filtering (de-bounce) operation is further performed by the detector 100 to filter noises of the requesting signal VS, such that the noise interference to the count N can be prevented.
FIG. 4 shows a control flow of the requesting-signal detection block 150 of the detector 100 according to the present invention. A checking block 200 will check the high-state period TH and the low-state period TL of the requesting signal VS in reference with the parameters T1, T2, T3, and T4. If the high-state period TH and the low-state period TL of the requesting signal VS meet the boundary conditions set by the parameters T1, T2, T3, and T4, both of a flag FH and a flag FL will be set as 1. If the flags FH and FL are both equal to 1 (logical high) (FH=1, FL=1), the value of the count N will be increased by one (N=N+1). Once the value of the count N is increased to be greater than M, the value of the count N will be set as M (Set N=M, if N>M). If at least one of the high-state period TH and the period TL of the requesting signal VS fails to meet the corresponding boundary condition set by the parameters T1 and T2 or by the parameters T3 and T4, the value of the count N will be decreased by one (N=N−1). Once the value of the count N is decreased to be lower than zero, the value of the count N will be set as zero (Set N=0, if N<0).
FIG. 5 shows a control flow of the checking block 200 of the requesting-signal detection block 150 according to the present invention. The checking block 200 is used to check the level of the requesting signal VS. While the level of the requesting signal VS is higher than the threshold VT, the high-state period TH will be checked according to the parameters T1 and T2, in other words, it will be checked whether the high-state period TH meets the boundary condition defined by the parameters T1 and T2. Whenever the high-state period TH is greater than the period T1 and, in the meantime, the high-state period TH is less than the period T2, the high-state period TH meets the corresponding boundary condition, and the flag FH will be set as 1 (logical high) (Set FH=1). Whenever the high-state period TH is equal to or less than the period T1 and, in the meantime, the high-state period TH is greater than or equal to the period T2, the high-state period TH does not meet the corresponding boundary condition, and the flag FH will be set as 0 (logical low) (Set FH=0).
While the level of the requesting signal VS is less than or equal to the threshold VT, the low-state period TL will be checked according to the parameters T3 and T4, in other words, it will be checked whether the low-state period TL meets the boundary condition defined by the parameters T3 and T4. Whenever the low-state period TL is greater than the period T3 and, in the meantime, the low-state period TL is less than the period T4, the low-state period TL meets the corresponding boundary condition, and the flag FL will be set as 1 (logical high) (Set FL=1). Whenever the low-state period TL is equal to or less than the period T3 and, in the meantime, TL is greater than or equal to the period T4, the low-state period TL does not meet the corresponding boundary condition, and the flag FL will be set as 0 (logical low) (Set FL=0).
FIG. 6 shows another aspect of the control flow in FIG. 3 according to the present invention. At the beginning of the control flow, the output voltage VCC is set as the initial voltage level V0. The high-state period TH of the requesting signal VS will be determined when the requesting signal VS is higher than the threshold VT. The low-state period TL of the requesting signal VS will be determined when the requesting signal VS is lower than the threshold VT. Criterion pairs are defined internally, such as a first criterion pair TH1 and TL1 to the last criterion pair THN and TLN. Once the high-state period TH equals to TH1 and the low-state period TL equals to TL1, the output voltage VCC will be set as V1. When the high-state period TH is not equal to TH1 and/or the low-state period TL is not equal to TL1, the high-state period TH and the low-state period TL will be checked continuously in reference with at least one of the other criterion pairs, such as the criterion pair TH2 and TL2, the criterion pair TH3 and TL3, etc. Whenever any criterion pair is met, the output voltage VCC will be set as its corresponding level. Once all criterion pairs are not met, the output voltage VCC will be kept as its present level. Different criterion pairs define different ratio combinations for the high-state period TH and the low-state period TL, and those criterion pairs will correspond to different levels of the output voltage VCC. It is also understood that determining different frequency of the requesting signal VS can also correspond to different levels of the output voltage VCC.
FIG. 7A shows an example of a cross-reference table of the high-state period TH, the low-state period TL and the output voltage VCC. The cross-reference table comprises different ratio combinations of the high-state period TH and the low-state period TL to determine the level of the output voltage VCC. Each ratio combination comprises a percentage of the period T being occupied by the high-state period TH and another percentage of the period T being occupied by the low-state period TL. It is preferred that possible ratio combinations can be defined at will and are not limited by the disclosed example in FIG. 7A. In an embodiment of the present invention, the ratio combination can include a varied high-state period TH associating with a fixed low-state period TL. Yet in another embodiment of the present invention, the ratio combination can include a fixed high-state period TH associating with a varied low-state period TL.
FIG. 7B shows an example of a cross-reference table of the output voltage VCC and the frequency (the reciprocal of the period T) of the requesting signal VS. Each set of the frequency (1/T Std.) has its maximum frequency (1/T Max.) and minimum frequency (1/T Min.) to develop a hysteresis frequency range. For instance, the output voltage VCC will be set at 12V when the frequency of the requesting signal VS falls between 160 Hz and 180 Hz. It is preferred that the hysteresis frequency range can be defined at will and are not limited by the disclosed example in FIG. 7B.
Even though the exampled levels of the output voltage VCC are not identical to each other, it can be understood that those exampled levels of the output voltage VCC can be totally or partially identical to each other. Simply using a periodical requesting signal VS transmitted from the device 20 and received by the programmable power supply 10 to achieve communication between the both reduces the complexity of circuit design. Furthermore, with proper hysteresis ranges definition for the high-state period TH, the low-state period TH, and the period T of the requesting signal VS, the programmable power supply 10 can switch its output voltage VCC to power the device 20 more precisely. Whenever the present invention is applied on the USB charger, the requesting signal VS can be transmitted through its intrinsic wire, such as D-wire, to reduce the manufacturing cost.
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. On 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.

## Claims

1. A method of programming a programmable power supply comprising:
generating a requesting signal in a device;
receiving said requesting signal in said programmable power supply; and
determining an output voltage of said programmable power supply in accordance with a frequency of said requesting signal;
wherein said output voltage of said programmable power supply is coupled to power a load of said device.

2. The method as claimed in claim 1 further comprising:
providing a de-bounce operation for filtering noises of said requesting signal.

3. The method as claimed in claim 1,
wherein said requesting signal comprises a high-state period and a low-state period; and
wherein said high-state period is defined during which a level of said requesting signal is higher than a threshold, and said low-state period is defined during which said level of said requesting signal is lower than said threshold.

4. The method as claimed in claim 3, wherein said output voltage of said programmable power supply is further determined by said high-state period of said requesting signal.

5. The method as claimed in claim 3, wherein said output voltage of said programmable power supply is further determined by said low-state period of said requesting signal.

6. The method as claimed in claim 1, wherein said output voltage of said programmable power supply is further determined by a period of said requesting signal.

7. A method of programming a programmable power supply, comprising:
generating a requesting signal in a device;
receiving said requesting signal in said programmable power supply;
detecting a high-state period of said requesting signal;
detecting a low-state period of said requesting signal;
checking whether said high-state period of said requesting signal meets a first boundary condition;
checking whether said low-state period of said requesting signal meets a second boundary condition; and
determining an output voltage of said programmable power supply in accordance with a result of said checking step of said high-state period and a result of said checking step of said low-state period;
wherein said output voltage of said programmable power supply is coupled to power a load of said device.

8. The method as claimed in claim 7 further comprising providing a de-bounce operation for filtering noises of said requesting signal.

9. The method as claimed in claim 7, wherein said high-state period is defined during which a level of said requesting signal is higher than a threshold, and said low-state period is defined during which said level of said requesting signal is lower than said threshold.

10. The method as claimed in claim 7, wherein said step of determining said output voltage of said programmable power supply comprises:
generating a count in accordance with said result of said checking step of said high-state period and said result of said checking step of said low-state period; and
determining said output voltage of said programmable power supply in accordance with a value of said count.

11. The method as claimed in claim 10, wherein when said high-state period of said requesting signal meets said first boundary condition and said low-state period of said requesting signal meets said second boundary condition, said value of said count is increased.

12. The method as claimed in claim 10, wherein when said high-state period of said requesting signal fails to meet said first boundary condition or said low-state period of said requesting signal fails to meet said second boundary condition, said value of said count is decreased.

13. A method of programming a programmable power supply, comprising:
generating a requesting signal in a device;
detecting said requesting signal in said programmable power supply; and
determining an output voltage of said programmable power supply in accordance with a ratio combination of a high-state period and a low-state period of said requesting signal;
wherein said output voltage of said programmable power supply is coupled to power a load of said device.

14. The method as claimed in claim 13 further comprising:
providing a de-bounce operation for filtering noises of said requesting signal.

15. The method as claimed in claim 13, wherein said high-state period is defined during which a level of said requesting signal is higher than a threshold, and said low-state period is defined during which said level of said requesting signal is lower than said threshold.

16. The method as claimed in claim 13, wherein said ratio combination comprises a percentage of a period of said requesting signal being occupied by said high-state period and another percentage of said period of said requesting signal being occupied by said low-state period.