PATENT DOCUMENT

Publication Number: US-9385589-B2
Application Number: US-201113296392-A
Country: US
Kind Code: B2

Title: Management of common mode noise frequencies in portable electronic devices

Abstract:
The disclosed embodiments provide a system that facilitates the use of a portable electronic device. During operation, the system detects a coupling of a power supply to the portable electronic device through a set of wires. Next, the system uses the set of wires to identify a type of the power supply. The system then periodically determines a switching frequency of the power supply based on the type of the power supply and a current drawn from the power supply. Finally, the system uses the switching frequency to facilitate the operation of a touch control in the portable electronic device. For example, if the switching frequency corresponds to a sensing frequency of the touch control, the system may change the sensing frequency to an alternative sensing frequency.

Claims:
What is claimed is: 
     
       1. A computer-implemented method for facilitating the use of a portable electronic device, comprising:
 establishing a communications link between a power supply and the portable electronic device; 
 using the communications link to identify a type of the power supply; 
 periodically determining a switching frequency of the power supply based on the type of the power supply and a current drawn from the power supply; and 
 using the switching frequency to facilitate the operation of a touch control in the portable electronic device, 
 wherein using the switching frequency to facilitate the operation of a touch control in the portable electronic device comprises managing the switching frequency of the power supply based on one or more sensing frequencies to reduce common mode noise associated with sensing touch input on the portable electronic device. 
 
     
     
       2. The computer-implemented method of  claim 1 , wherein using the communications link to identify the type of the power supply involves:
 obtaining an identifier corresponding to the type from an analog-to-digital converter (ADC) coupled to the communications link. 
 
     
     
       3. The computer-implemented method of  claim 2 , wherein the identifier is calculated by the ADC using one or more voltage dividers. 
     
     
       4. The computer-implemented method of  claim 2 , wherein periodically determining the switching frequency of the power supply based on the type of the power supply and the current drawn from the power supply involves:
 using the identifier and the current to obtain the switching frequency from a lookup table. 
 
     
     
       5. The computer-implemented method of  claim 1 , wherein the communications link comprises a set of wires. 
     
     
       6. The computer-implemented method of  claim 5 , wherein the set of wires comprises:
 a power wire; 
 one or more data wires; and 
 a ground wire. 
 
     
     
       7. The computer-implemented method of  claim 1 , wherein the touch control is associated with at least one of a touchscreen and a touchpad. 
     
     
       8. The computer-implemented method of  claim 1 , wherein using the switching frequency to facilitate the operation of the touch control in the portable electronic device involves:
 if the switching frequency corresponds to a sensing frequency of the touch control, changing the sensing frequency to an alternative sensing frequency. 
 
     
     
       9. The computer-implemented method of  claim 1 , further comprising:
 temporarily halting operation of the power supply upon receiving a halt command from the portable electronic device to the power supply, wherein the halted operation further reduces common mode noise associated with sensing touch input on the portable electronic device. 
 
     
     
       10. The computer-implemented method of  claim 9 , further comprising:
 resuming operation of the power supply upon receiving a resume command from the portable electronic device to the power supply. 
 
     
     
       11. A system for facilitating the use of a portable electronic device, comprising:
 an interface configured to establish a communications link between a power supply and the portable electronic device and 
 a management apparatus configured to: 
 use the communications link to identify a type of the power supply; 
 periodically determine a switching frequency of the power supply based on the type of the power supply and a current drawn from the power supply; and 
 use the switching frequency to facilitate the operation of a touch control in the portable electronic device, 
 wherein using the switching frequency to facilitate the operation of a touch control in the portable electronic device comprises managing the switching frequency of the power supply based on one or more sensing frequencies to reduce common mode noise associated with sensing touch input on the portable electronic device. 
 
     
     
       12. The system of  claim 11 , wherein using the switching frequency to facilitate the operation of the touch control in the portable electronic device involves:
 if the switching frequency corresponds to a sensing frequency of the touch control, changing the sensing frequency to an alternative sensing frequency. 
 
     
     
       13. The system of  claim 11 , wherein the management apparatus correspond to at least one of a processor and a power-management unit (PMU). 
     
     
       14. The system of  claim 11 , wherein using the communications link to identify the type of the power supply involves:
 obtaining an identifier corresponding to the type from an analog-to-digital converter (ADC) coupled to the communications link. 
 
     
     
       15. The system of  claim 14 , wherein periodically determining the switching frequency of the power supply based on the type of the power supply and the current drawn from the power supply involves:
 using the identifier and the current to obtain the switching frequency from a lookup table. 
 
     
     
       16. The system of  claim 11 , wherein the communications link comprises a set of wires. 
     
     
       17. The system of  claim 16 , wherein the set of wires comprises:
 a power wire; 
 one or more data wires; and 
 a ground wire. 
 
     
     
       18. The system of  claim 11 , wherein the management apparatus is further configured to:
 temporarily halt operation of the power supply upon receiving a halt command from the portable electronic device to the power supply, wherein the halted operation further reduces common mode noise associated with sensing touch input on the portable electronic device. 
 
     
     
       19. The system of  claim 18 , wherein the management apparatus is further configured to:
 resume operation of the power supply upon receiving a resume command from the portable electronic device to the power supply. 
 
     
     
       20. A computer-readable storage medium storing instructions that when executed by a computer cause the computer to perform a method for facilitating the use of a portable electronic device, the method comprising:
 establishing a communications link between a power supply and the portable electronic device; 
 using the communications link to identify a type of the power supply; 
 periodically determining a switching frequency of the power supply based on the type of the power supply and a current drawn from the power supply; and 
 using the switching frequency to facilitate the operation of a touch control in the portable electronic device, 
 wherein using the switching frequency to facilitate the operation of a touch control in the portable electronic device comprises managing the switching frequency of the power supply based on one or more sensing frequencies to reduce common mode noise associated with sensing touch input on the portable electronic device. 
 
     
     
       21. The computer-readable storage medium of  claim 20 , the method further comprising:
 temporarily halting operation of the power supply upon receiving a halt command from the portable electronic device to the power supply, wherein the halted operation further reduces common mode noise associated with sensing touch input on the portable electronic device. 
 
     
     
       22. The computer-readable storage medium of  claim 21 , the method further comprising:
 resuming operation of the power supply upon receiving a resume command from the portable electronic device to the power supply. 
 
     
     
       23. The computer-readable storage medium of  claim 20 , wherein using the switching frequency to facilitate the operation of the touch control in the portable electronic device involves:
 if the switching frequency corresponds to a sensing frequency of the touch control, changing the sensing frequency to an alternative sensing frequency. 
 
     
     
       24. The computer-readable storage medium of  claim 20 , wherein using the communications link to identify the type of the power supply involves:
 obtaining an identifier corresponding to the type from an analog-to-digital converter (ADC) coupled to the wires. 
 
     
     
       25. The computer-readable storage medium of  claim 24 , wherein periodically determining the switching frequency of the power supply based on the type of the power supply and the current drawn from the power supply involves:
 using the identifier and the current to obtain the switching frequency from a lookup table. 
 
     
     
       26. The computer-readable storage medium of  claim 20 , wherein the communications link comprises a set of wires. 
     
     
       27. The computer-readable storage medium of  claim 26 , wherein the set of wires comprises:
 a power wire; 
 one or more data wires; and 
 a ground wire.

Description:
BACKGROUND 
     1. Field 
     The present embodiments relate to power supplies for portable electronic devices. More specifically, the present embodiments relate to techniques for managing common mode noise frequencies generated by power supplies for portable electronic devices. 
     2. Related Art 
     Flyback converters may be used to convert alternating current (AC) to direct current (DC) in low-power applications such as mobile phone chargers and/or laptop computer power supplies. For example, an external power supply (e.g., power brick) for a laptop computer may use a flyback converter to convert AC mains power from a power outlet into low-voltage DC that can be used by components in the laptop computer. 
     To increase the efficiency of a flyback converter, the switching frequency of the flyback converter may be varied in response to load and/or input voltage. For example, a moving load generated by a charging battery and/or the switching off of a touchscreen in a mobile phone may cause the switching frequency of the mobile phone&#39;s charger to sweep across a range of frequencies, thus lowering switching losses in the flyback converter. 
     On the other hand, dynamic changes to the flyback converter&#39;s switching frequency may generate common mode noise that interferes with the sensing of touch input on a portable electronic device coupled to the flyback converter. For example, the flyback converter&#39;s switching frequency may sweep through a frequency band associated with the sensing frequency of a touch control on the portable electronic device. While the switching frequency remains in the frequency band, common mode interference from the flyback converter may prevent the touch control from accurately detecting touch input on the portable electronic device. As a result, efficient operation of the flyback converter may reduce the performance of the touch control and negatively impact the user experience with the portable electronic device. 
     Hence, what is needed is a mechanism for managing the frequencies of common mode noise generated by power supplies of portable electronic devices. 
     SUMMARY 
     The disclosed embodiments provide a system that facilitates the use of a portable electronic device. During operation, the system detects a coupling of a power supply to the portable electronic device through a set of wires. Next, the system uses the set of wires to identify a type of the power supply. The system then periodically determines a switching frequency of the power supply based on the type of the power supply and a current drawn from the power supply. Finally, the system uses the switching frequency to facilitate the operation of a touch control in the portable electronic device. For example, if the switching frequency corresponds to a sensing frequency of the touch control, the system may change the sensing frequency to an alternative sensing frequency. 
     In some embodiments, using the set of wires to identify the type of the power supply involves obtaining an identifier corresponding to the type from an analog-to-digital converter (ADC) coupled to the wires. The identifier may be calculated by the ADC using one or more voltage dividers. 
     In some embodiments, periodically determining the switching frequency of the power supply based on the type of the power supply and the current drawn from the power supply involves using the identifier and the current to obtain the switching frequency from a lookup table. 
     In some embodiments, the set of wires includes a power wire, one or more data wires, and a ground wire. 
     In some embodiments, the touch control is associated with at least one of a touchscreen and a touchpad. 
     The disclosed embodiments also provide a system that operates a power supply for a portable electronic device. During operation, the system establishes a communications link between the power supply and the portable electronic device. Next, the system uses the communications link to identify a type of the portable electronic device and uses the type of the portable electronic device to determine a set of sensing frequencies for a touch control of the portable electronic device. Finally, the system manages a switching frequency of the power supply based on the sensing frequencies to reduce common mode noise associated with sensing touch input on the portable electronic device. 
     In some embodiments, the system also temporarily halts operation of the power supply upon receiving a halt command from the portable electronic device to the power supply, wherein the halted operation further reduces common mode noise associated with sensing touch input on the portable electronic device. The system may then resume operation of the power supply upon receiving a resume command from the portable electronic device to the power supply. 
     In some embodiments, using the type of the portable electronic device to determine the set of sensing frequencies for the touch control involves using the type of the portable electronic device to obtain the set of sensing frequencies from a lookup table. 
     In some embodiments, managing the switching frequency of the power supply based on the sensing frequencies to reduce common mode noise associated with sensing touch input on the portable electronic device involves modulating the switching frequency so that the power supply avoids frequency bands associated with the sensing frequencies. 
    
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
         FIG. 1  shows a schematic of a system in accordance with the disclosed embodiments. 
         FIG. 2  shows a system for operating a power supply for a portable electronic device in accordance with the disclosed embodiments. 
         FIG. 3  shows an exemplary circuit for identifying a type of a power supply in accordance with the disclosed embodiments. 
         FIG. 4  shows a flowchart illustrating the process of facilitating the use of a portable electronic device in accordance with the disclosed embodiments. 
         FIG. 5  shows a flowchart illustrating the process of operating a power supply for a portable electronic device in accordance with the disclosed embodiments. 
         FIG. 6  shows a portable electronic device in accordance with the disclosed embodiments. 
     
    
    
     In the figures, like reference numerals refer to the same figure elements. 
     DETAILED DESCRIPTION 
     The following description is presented to enable any person skilled in the art to make and use the embodiments, and is provided in the context of a particular application and its requirements. Various modifications to the disclosed embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be applied to other embodiments and applications without departing from the spirit and scope of the present disclosure. Thus, the present invention is not limited to the embodiments shown, but is to be accorded the widest scope consistent with the principles and features disclosed herein. 
     The data structures and code described in this detailed description are typically stored on a computer-readable storage medium, which may be any device or medium that can store code and/or data for use by a computer system. The computer-readable storage medium includes, but is not limited to, volatile memory, non-volatile memory, magnetic and optical storage devices such as disk drives, magnetic tape, CDs (compact discs), DVDs (digital versatile discs or digital video discs), or other media capable of storing code and/or data now known or later developed. 
     The methods and processes described in the detailed description section can be embodied as code and/or data, which can be stored in a computer-readable storage medium as described above. When a computer system reads and executes the code and/or data stored on the computer-readable storage medium, the computer system performs the methods and processes embodied as data structures and code and stored within the computer-readable storage medium. 
     Furthermore, methods and processes described herein can be included in hardware modules or apparatus. These modules or apparatus may include, but are not limited to, an application-specific integrated circuit (ASIC) chip, a field-programmable gate array (FPGA), a dedicated or shared processor that executes a particular software module or a piece of code at a particular time, and/or other programmable-logic devices now known or later developed. When the hardware modules or apparatus are activated, they perform the methods and processes included within them. 
     The disclosed embodiments provide a method and system for facilitating use of a portable electronic device and/or a power supply for the portable electronic device. As shown in  FIG. 1 , the power supply  100  includes a power source  110  and a power converter  120 . Power converter  120  may obtain an input voltage from power source  110  and convert the input voltage into an output voltage that is used to drive a load in the portable electronic device  130 . For example, power converter  120  may convert alternating current (AC) mains power into low-voltage direct current (DC) that is used to charge a battery and/or power components of a mobile phone, laptop computer, portable media player, and/or tablet computer. 
     Furthermore, power supply  100  may be designed to accommodate size constraints associated with portable electronic device  130 . For example, the small form factor of portable electronic device  130  may require the design of a similarly small power supply  100  for use with portable electronic device  130 . Moreover, gradual reductions in the size and/or weight of portable electronic device  130  over time may be accompanied by corresponding reductions in the size and/or weight of power supply  100  to further improve the portability of portable electronic device  130 . 
     Conversely, such size constraints may result in power losses that reduce the efficiency of power supply  100 . In particular, power conversion in power supply  100  may involve a tradeoff between size and efficiency, in which larger electronic components (e.g., transformers, inductors, etc.) may generate a given output voltage at a lower switching frequency, and thus dissipate less power, than smaller electronic components. Because a small form factor for power supply  100  may require the use of small electronic components within power converter  120 , power supply  100  may be associated with higher switching losses than a power supply with larger electronic components. 
     To mitigate switching losses in power supply  100 , the switching frequency of power converter  120  may be varied in response to changes in load (e.g., from portable electronic device  130 ) and/or input voltage (e.g., from power source  110 ). For example, the charging of a battery in portable electronic device  130  and/or the powering on or off of a component (e.g., processor, touchscreen, speakers, etc.) in portable electronic device  130  may cause the switching frequency of power converter  120  to sweep across frequencies ranging between 100 KHz and 400 KHz. 
     However, dynamic changes to the switching frequency of power converter  120  may also generate common mode noise that interferes with the operation of a touch control  140  in portable electronic device  130 . More specifically, the switching frequency may sweep through a frequency band associated with the sensing frequency of touch control  140 , thus interfering with the ability of touch control  140  to accurately detect touch input on portable electronic device  130 . 
     In one or more embodiments, power supply  100  and/or portable electronic device  130  include functionality to facilitate the operation of touch control  140  by reducing common mode noise associated with sensing touch input on portable electronic device  130 . An interface  150  between power supply  100  and portable electronic device  130  may be used by portable electronic device  130  to identify a type of power supply  100  and/or by power supply  100  to identify a type of portable electronic device  130 . The identified type(s) may then be used by portable electronic device  130  and/or power supply  100  to determine the switching frequency of power supply  100  and/or a set of sensing frequencies for touch control  140 , respectively. Finally, the switching and/or sensing frequencies may be adjusted by power supply  100  and/or portable electronic device  130 , respectively, to facilitate operation of touch control  140 . For example, portable electronic device  130  may change the sensing frequency of touch control  140  to an alternative sensing frequency if the switching frequency corresponds to the current sensing frequency of touch control  140 . Alternatively, power supply  100  may modulate the switching frequency so that power supply  100  avoids frequency bands associated with the sensing frequencies of touch control  140 . 
       FIG. 2  shows a system for operating a power supply  204  for a portable electronic device  202  in accordance with the disclosed embodiments. Power supply  204  may be coupled to portable electronic device  202  through an interface  210  such as Universal Serial Bus (USB), MagSafe (MagSafe™ is a registered trademark of Apple Inc.), and/or 1-Wire (1-Wire™ is a registered trademark of Maxim Integrated Products, Inc.). In addition, interface  210  may include a set of wires, such as a power wire (e.g., “V DC ”), a ground wire (e.g., “GND”), and/or one or more data wires (e.g., “D+” and “D−”). 
     As shown in  FIG. 2 , an input voltage is supplied from a power source  220 . For example, the input voltage may be obtained as AC mains power from a power outlet. The input voltage may be converted into an output voltage by the flyback converter, which contains a primary winding  206 , a secondary winding  208 , and a switch  212 . Primary winding  206  and secondary winding  208  may form a transformer, and switch  212  may correspond to a metal-oxide-semiconductor field-effect transistor (MOSFET). 
     To charge the flyback converter, a microcontroller  224  in power supply  204  may close switch  212 . The varying current in primary winding  206  may create a varying magnetic flux in the transformer, resulting in a varying voltage (e.g., “V SEC ”) in secondary winding  208 . Microcontroller  224  may then discharge the flyback converter by opening switch  212 . Once switch  212  is opened, current from secondary winding  208  may be collected by a capacitor  214 , which supplies the current to portable electronic device  202  and acts as a low-pass filter by reducing voltage ripple caused by fluctuating current through secondary winding  208 . A power-management unit (PMU)  218  on the portable electronic device may then use the current to charge a battery  226  on the portable electronic device and/or power processor  216  and/or other components on the portable electronic device. 
     As mentioned above, the system of  FIG. 2  may include functionality to reduce common mode noise associated with sensing touch input on portable electronic device  202 . First, a communications link may be established between power supply  204  and portable electronic device  202  through interface  210 . For example, processor  216  and/or PMU  218  may establish the communications link over a USB interface  210  with microprocessor  224 . Next, microcontroller  224  may use the communications link to identify a type of portable electronic device  202 . For example, microcontroller  224  may request the model of portable electronic device  202  from a processor  216  in portable electronic device  202 . Processor  216  may then transmit an identifier corresponding to the model to microcontroller  224  via an interface circuit  222  (e.g., USB PHY chip) and interface  210 . 
     Microcontroller  224  may then use the type of portable electronic device  202  to determine a set of sensing frequencies for a touch control of portable electronic device  202 . For example, microcontroller  224  may use the type of portable electronic device  202  to obtain the set of sensing frequencies from a lookup table. Finally, microcontroller  224  may manage the switching frequency of power supply  204  (e.g., switch  212 ) based on the sensing frequencies to reduce common mode noise associated with sensing touch input on portable electronic device  202 . For example, microcontroller  224  may modulate the switching frequency so that power supply  204  avoids (e.g., skips) frequency bands associated with the sensing frequencies of the touch control during operation of power supply  204 . 
     To further reduce common mode noise associated with sensing touch input on portable electronic device  202 , microcontroller  224  may temporarily halt operation of power supply  204  upon receiving a halt command from portable electronic device  202  to power supply  204  (e.g., through interface  210 ). During the halted operation, portable electronic device  202  may identify a change in the noise spectrum associated with the sensing frequency of the touch control, thus allowing the touch control to more accurately detect touch input on portable electronic device  202 . Microcontroller  224  may then resume operation of power supply  204  upon receiving a resume command from portable electronic device  202  to power supply  204  (e.g., through interface  210 ). Alternatively, microcontroller  224  may automatically resume operation of power supply  204  after the operation of power supply  204  has been halted for a pre-specified period (e.g., 100 milliseconds). 
     Those skilled in the art will appreciate that microcontroller  224  may not be present on power supplies for some portable electronic devices, such as mobile phones and/or tablet computers. To facilitate operation of touch controls on such portable electronic devices, the types and switching frequencies of the power supplies may be identified by the portable electronic devices, and the sensing frequencies of touch controls on the portable electronic devices may be changed based on the switching frequencies, as discussed in further detail below with respect to  FIG. 3 . 
       FIG. 3  shows an exemplary circuit for identifying a type of a power supply (e.g., power supply  100  of  FIG. 1 ) in accordance with the disclosed embodiments. The power supply may be coupled to a portable electronic device using a set of wires, including a power wire (e.g., “V DC ”), a ground wire (e.g., “GND”), and one or more data wires (e.g., “D+” and “D−”). In addition, the power supply may lack a microcontroller (e.g., microcontroller  224  of  FIG. 2 ) with functionality to communicate with the portable electronic device. Instead, the circuit of  FIG. 3  may be substituted for the microcontroller in the power supply to facilitate the sensing of touch input on the portable electronic device. 
     In particular, the circuit may include a set of resistors  302 - 308  forming two voltage dividers. The first voltage divider may include resistors  302 - 304 , and the second voltage divider may include resistors  306 - 308 . The first voltage divider may be used to obtain a first output voltage from the “D+” data wire, and the second voltage divider may be used to obtain a second output voltage from the “D−” data wire. 
     The output voltages may be used by a management apparatus on the portable electronic device to identify the type of the power supply. For example, a processor (e.g., processor  216  of  FIG. 2 ) and/or PMU (e.g., PMU  218  of  FIG. 2 ) corresponding to the management apparatus may obtain an identifier corresponding to the type from an analog-to-digital converter (ADC) coupled to the wires. The management apparatus may then periodically determine the switching frequency of the power supply based on the type of the power supply and a current drawn from the power supply. Continuing with the above example, the processor and/or PMU may periodically measure the current drawn from the power supply using a sense resistor, using a field-effect transistor (FET), and/or by measuring the voltage drop across a resistor. The processor and/or PMU may then use the identifier obtained from the ADC and the current to obtain the switching frequency from a lookup table. 
     Finally, the management apparatus may use the switching frequency to facilitate the operation of a touch control in the portable electronic device. For example, the processor and/or PMU may change the sensing frequency of the touch control to an alternative sensing frequency if the switching frequency corresponds to a current sensing frequency of the touch control to allow the touch control to more accurately detect touch input on a touchscreen and/or touchpad of the portable electronic device. 
       FIG. 4  shows a flowchart illustrating the process of facilitating the use of a portable electronic device in accordance with the disclosed embodiments. In one or more embodiments, one or more of the steps may be omitted, repeated, and/or performed in a different order. Accordingly, the specific arrangement of steps shown in  FIG. 4  should not be construed as limiting the scope of the embodiments. 
     First, coupling of a power supply to the portable electronic device is detected through a set of wires (operation  402 ). The set of wires may form an interface between the power supply and the portable electronic device, such as a USB, MagSafe, and/or 1-Wire interface. Next, the wires are used to identify a type of the power supply (operation  404 ). For example, an ADC coupled to the wires may use one or more voltage dividers to generate an identifier (e.g., code) corresponding to the type. The ADC may then transmit the identifier to a processor and/or PMU on the portable electronic device. 
     The switching frequency of the power supply is then determined based on the type of the power supply and the current drawn from the power supply (operation  406 ). For example, the portable electronic device may use the identifier corresponding to the type and the current to obtain the switching frequency from a lookup table. Finally, the switching frequency is used to facilitate the operation of a touch control in the portable electronic device (operation  408 ). For example, if the switching frequency corresponds to a sensing frequency of the touch control, the sensing frequency may be changed to an alternative sensing frequency. In turn, the change in sensing frequency may reduce common mode noise associated with sensing touch input on the portable electronic device, thus allowing the touch control to more accurately detect touch input from a touchscreen, touchpad, and/or other touch-sensitive input device on the portable electronic device. 
     The power supply may continue to be coupled to the portable electronic device (operation  410 ). For example, the power supply may be coupled to the portable electronic device to charge a battery in the portable electronic device and/or power components of the portable electronic device. During coupling of the power supply to the portable electronic device, the switching frequency of the power supply is periodically determined based on the type of the power supply and the current drawn from the power supply (operation  406 ). The switching frequency is then used to facilitate the operation of the touch control (operation  408 ) by, for example, adjusting the sensing frequency of the touch control based on the switching frequency. Such management of common mode noise frequencies in the portable electronic device may continue until the power supply is no longer coupled to the portable electronic device. 
       FIG. 5  shows a flowchart illustrating the process of operating a power supply for a portable electronic device in accordance with the disclosed embodiments. In one or more embodiments, one or more of the steps may be omitted, repeated, and/or performed in a different order. Accordingly, the specific arrangement of steps shown in  FIG. 5  should not be construed as limiting the scope of the embodiments. 
     Initially, a communications link is established between the power supply and the portable electronic device (operation  502 ). The communications link may be established through an interface between the power supply and the portable electronic device. Next, the communications link is used to identify a type of the portable electronic device (operation  504 ), and the type is used to determine a set of sensing frequencies for a touch control of the portable electronic device (operation  506 ). For example, the power supply may request the type from a processor and/or PMU in the portable electronic device, and the processor and/or PMU may transmit an identifier corresponding to the type to the power supply through the interface. The power supply may then match the identifier to a set of sensing frequencies in a lookup table. 
     The switching frequency of the power supply is also managed based on the sensing frequencies to reduce common mode noise associated with sensing touch input on the portable electronic device (operation  508 ). For example, the switching frequency may be modulated so that the power supply avoids frequency bands associated with the sensing frequencies. In other words, the switching frequency may skip the frequency bands associated with the sensing frequencies during sweeping of the switching frequency across a range of frequencies (e.g., 100-400 KHz) in response to changes in the load and/or input voltage of the power supply. 
     Moreover, a halt command may be received (operation  510 ) from the portable electronic device. If the halt command is received, operation of the power supply is temporarily halted (operation  512 ) to further reduce common mode noise associated with sensing touch input on the portable electronic device. While operation of the power supply is halted, a change in the noise spectrum associated with the sensing frequency may be identified, thus allowing the touch control to more accurately detect touch input on the portable electronic device. Operation of the power supply may continue to be halted (operation  512 ) until a resume command is received (operation  514 ) from the portable electronic device. If the resume command is received, operation of the power supply is resumed (operation  516 ). Alternatively, operation of the power supply may resume automatically after operation has been halted for a pre-specified period. 
     Reduction of common mode noise may continue while the power supply is coupled to the portable electronic device (operation  518 ). During coupling of the power supply to the portable electronic device, the switching frequency of the power supply is managed based on the sensing frequencies of the touch control (operation  508 ), and operation of the power supply may be temporarily halted and resumed based on commands received from the portable electronic device (operations  510 - 516 ). Such operation of the power supply may continue until the power supply is no longer coupled to the portable electronic device. 
     The above-described power supply can generally be used in any type of electronic device. For example,  FIG. 6  illustrates a portable electronic device  600  which includes a processor  602 , a memory  604  and a display  608 , which are all powered by a power supply  606 . Portable electronic device  600  may correspond to a laptop computer, tablet computer, mobile phone, PDA, portable media player, digital camera, and/or other type of battery-powered electronic device with a touchscreen, touchpad, and/or other touch-sensitive input device. Power supply  606  may include a flyback converter with a varying switching frequency. 
     To reduce common mode noise associated with sensing touch input on portable electronic device  600 , an interface between portable electronic device  600  and power supply  606  may be used to detect coupling of power supply  606  to portable electronic device  600  through a set of wires. The set of wires may also be used to identify a type of power supply  606 . Next, a switching frequency of power supply  606  may be determined based on the type of power supply  606  and a current drawn from power supply  606 . Finally, the switching frequency may be used to facilitate the operation of a touch control in the portable electronic device. For example, if the switching frequency corresponds to the sensing frequency of the touch control, the sensing frequency of the touch control may be changed to an alternative sensing frequency. 
     The foregoing descriptions of various embodiments have been presented only for purposes of illustration and description. They are not intended to be exhaustive or to limit the present invention to the forms disclosed. Accordingly, many modifications and variations will be apparent to practitioners skilled in the art. Additionally, the above disclosure is not intended to limit the present invention.

Metadata:
Filing Date: 20111115
Publication Date: 20160705
Grant Date: 20160705
Priority Date: 20111115
Inventors: SIMS NICHOLAS A.
Assignee: APPLE INC
CPC Classifications: [{"code": "G06F1/263", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F3/0418", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F1/26", "inventive": true, "first": false, "tree": "[]"}, {"code": "H02M1/44", "inventive": true, "first": true, "tree": "[]"}, {"code": "H02M3/33507", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F3/0418", "inventive": true, "first": true, "tree": "[]"}, {"code": "G06F1/26", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F1/263", "inventive": true, "first": false, "tree": "[]"}, {"code": "H02M1/44", "inventive": true, "first": false, "tree": "[]"}, {"code": "H02M3/33507", "inventive": true, "first": false, "tree": "[]"}, {"code": "H02M3/33507", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F3/0418", "inventive": true, "first": true, "tree": "[]"}, {"code": "G06F1/263", "inventive": true, "first": false, "tree": "[]"}, {"code": "H02M1/44", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F1/26", "inventive": true, "first": false, "tree": "[]"}]
Family ID: 48280496