PATENT DOCUMENT

Publication Number: US-8493755-B2
Application Number: US-201113097877-A
Country: US
Kind Code: B2

Title: Power supply with zero power consumption capability

Abstract:
Power supply devices are provided that can include power regulating circuitry for regulating (e.g., transforming or converting) electric power to be passed to an electronic device. A power supply device can also include control circuitry coupled with the regulating circuitry. The control circuitry can determine when the power supply device is coupled with an electronic device. The control circuitry can control the operation of the regulating circuitry based on whether or not the power supply device is coupled with the electronic device.

Claims:
What is claimed is: 
     
       1. A power supply device comprising:
 a low-power regulating circuitry operable to receive an electric power signal and output a regulated electric power signal up to a first power limit; 
 a high-power regulating circuitry operable to receive an electric power signal and output the regulated electric power signal up to a second power limit, wherein the second power limit is higher than the first power limit; 
 a first switch disposed between the low-power regulating circuitry and the output of the power supply device, operable to switch between at least an open position and a closed position; 
 a second switch disposed between the high-power regulating circuitry and the output of the power supply device, operable to switch between at least an open position and a closed position; 
 control circuitry powered by the low-power regulating circuitry and operable to selectively enable the low-power and the high-power regulating circuitry when the power supply device is coupled with an electronic device, wherein the selectively enabling is independent from the position of the first and the second switches, wherein the selectively enabling is independent from a power level of the electric power signal. 
 
     
     
       2. The device of  claim 1 , wherein the low-power and the high-power regulating circuitry each comprises an AC-to-DC converter. 
     
     
       3. The device of  claim 1 , wherein the first and second power limits are current limits. 
     
     
       4. The device of  claim 1 , wherein the control circuitry is operable to independently enable the low-power regulating circuitry and the high-power regulating circuitry. 
     
     
       5. The device of  claim 1 , wherein the control circuitry is operable to determine when the power supply device is coupled with the electronic device. 
     
     
       6. The device of  claim 1 , wherein the control circuitry comprises a processor. 
     
     
       7. The device of  claim 1 , wherein the control circuitry comprises a sensor operable to determine when the power supply device is coupled with the electronic device. 
     
     
       8. The device of  claim 1 , wherein the control circuitry comprises communications circuitry operable to receive data from the electronic device coupled with the power supply device. 
     
     
       9. The device of  claim 1 , wherein at least a portion of the control circuitry is located in interface hardware between the power supply device and the electronic device. 
     
     
       10. The device of  claim 9 , further comprising a connector for coupling with the electronic device, wherein the control circuitry comprises a sensor located in the connector for determining when the power supply device is coupled with the electronic device. 
     
     
       11. The device of  claim 1 , further comprising a power storage device coupled with the control circuitry and operable to power the control circuitry when both the low-power and the high-power regulating circuitry are not enabled. 
     
     
       12. The device of  claim 11 , wherein the power storage device is rechargeable, and wherein either the low-power or the high-power regulating circuitry, when enabled, is operable to recharge the power storage device. 
     
     
       13. The device of  claim 1 , wherein the control circuitry is operable to selectively disable the low-power and the high-power regulating circuitry when the power supply device is not coupled with any electronic device. 
     
     
       14. A method for providing electric power to an electronic device, the method comprising:
 coupling a power supply device to a source of raw electrical power, wherein the power supply device comprises a low-power and a high-power regulating circuit and a first and a second switch coupled between the low-power and the high-power regulating circuits and the electronic device and operable to switch between at least an open position and a closed position; 
 providing power to at least a portion of a control circuitry with the low-power regulating circuit; 
 determining when the power supply device is coupled with the electronic device; and 
 selectively enabling the low-power and high-power regulating circuit based on the determining, wherein the selectively enabling is independent from the position of the switches, wherein the selectively enabling is independent from a power level of the raw electric power. 
 
     
     
       15. The method of  claim 14 , wherein the determining comprises monitoring a characteristic of a power line in the power supply device, the characteristic being selected from the group consisting of:
 a voltage level; 
 a current level; and 
 a resistance. 
 
     
     
       16. The method of  claim 15 , further comprising:
 coupling the power line with the control circuitry for monitoring the characteristic; and 
 decoupling the power line from the control circuitry when the determining indicates that the power supply device is not coupled with the electronic device. 
 
     
     
       17. The method of  claim 14 , wherein the determining comprises: monitoring a resistance between a ground potential and a shield of a cable for coupling the power supply device with the electronic device. 
     
     
       18. The method of  claim 14 , wherein the determining comprises receiving data from the electronic device. 
     
     
       19. The method of  claim 14 , further comprising using electric power from a power storage device within the power supply device before the selectively enabling. 
     
     
       20. The method of  claim 14 , wherein the selectively enabling comprises selectively enabling the high-power regulating circuitry when the determining indicates that the power supply device is coupled with the electronic device. 
     
     
       21. The method of  claim 14 , wherein the low-power and high-power regulating circuit each comprises an AC-to-DC converter. 
     
     
       22. The method of  claim 14 , further comprising selectively disabling the low-power and high-power regulating circuit based on the determining. 
     
     
       23. The method of  claim 22 , wherein:
 the selectively enabling comprises selectively enabling the low-power and high-power regulating circuit when the determining indicates that the power supply device is coupled with the electronic device; and 
 the selectively disabling comprises selectively disabling the low-power and high-power regulating circuit when the determining indicates that the power supply device is not coupled with any electronic device. 
 
     
     
       24. The method of  claim 14 , wherein the selectively enabling comprises:
 selectively enabling the low-power regulating circuit and disabling the high-power regulating circuit when the determining indicates that the power supply device is not coupled with any electronic device; and 
 selectively enabling the high-power regulating circuit and disabling the low-power regulating circuit when the determining indicates that the power supply device is coupled with the electronic device. 
 
     
     
       25. The method of  claim 24 , further comprising:
 opening the switch at the output of the high-power regulating circuit when the determining indicates that the power supply device is not coupled with any electronic device; and 
 closing the switch at the output of the high-power regulating circuit when the determining indicates that power supply device is coupled with the electronic device. 
 
     
     
       26. A power supply device comprising:
 a first and a second AC-to-DC converter each operable to receive an electric power signal with an alternating current and output an electric power signal with a direct current; 
 a first switch coupled with the first AC-to-DC converter and operable to switch between at least an open position and a closed position; 
 a second switch coupled with the second AC-to-DC converter and operable to switch between at least an open position and a closed position; and 
 control circuitry coupled with the first and second converters, powered by the first converter, and operable to selectively enable the converters when the power supply device is coupled with an electronic device, wherein the selectively enabling is independent from the position of the switches, wherein the selectively enabling is independent from a power level of the electric power signal, 
 wherein the first converter comprises a low-power regulating circuitry portion operable to output the electric power signal up to a first power limit, wherein the second converter comprises a high-power regulating circuitry portion operable to output the electric power signal up to a second power limit, wherein the second power limit is higher than the first power limit. 
 
     
     
       27. A method for providing electric power to an electronic device, the method comprising:
 coupling a power supply device to a source of raw electrical power, wherein the power supply device comprises a first and a second AC-to-DC converter and a first and a second switch coupled with the first and the second AC-to-DC converters and operable to switch between at least an open position and a closed position; 
 determining when the power supply device is coupled with the electronic device; and 
 selectively enabling the first and the second AC-to-DC converters based on the determining, wherein the selectively enabling is independent from the position of the switches, wherein the selectively enabling is independent from a power level of the raw electric power, 
 wherein the first converter comprises a low-power regulating circuitry portion operable to output the electric power up to a first power limit, wherein the second converter comprises a high-power regulating circuitry portion operable to output the electric power up to a second power limit, wherein the second power limit is higher than the first power limit. 
 
     
     
       28. The method of  claim 27 , wherein the selectively enabling comprises selectively enabling the second AC-to-DC converter when the determining indicates that the power supply device is coupled with the electronic device.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of commonly-assigned U.S. patent application Ser. No. 12/239,345, filed on Sep. 26, 2008, and now issued as U.S. Pat. No. 7,956,591 on Jun. 7, 2011, the contents of which are hereby incorporated by reference in their entirety. 
    
    
     FIELD OF THE INVENTION 
     This relates to apparatus and methods for providing electric power to an electronic device and, more particularly, to apparatus and methods for limiting the consumption of power when providing electric power to an electronic device. 
     BACKGROUND OF THE DISCLOSURE 
     Various factors limit the efficiency and functionality of traditional power supply devices used for powering and/or charging electronic devices (e.g., cellular telephones and portable media devices). For example, most traditional power supply devices convert an alternating current (“AC”) input to a regulated direct current (“DC”) output whenever the power supply device is plugged into a power outlet (e.g., an outlet coupled with a power grid). This wastes power because the power supply continuously provides a regulated power signal even if it is not powering an electronic device. Moreover, it is difficult to design efficient power supply devices for portable electronic devices due to size limitations associated with portability. Additionally, many portable electronic devices have limited interfaces for coupling with a power supply device so it can be difficult for a traditional power supply device to determine when it is coupled with an electronic device. For example, a portable electronic device may include a connector with only a power signal wire and a ground wire, and therefore, no extra wires can be used by a traditional power supply device to determine when it is coupled with the electronic device. 
     SUMMARY OF THE DISCLOSURE 
     Power supply devices are provided that can consume less power when not coupled with an electronic device. Such power supply devices can include power regulating circuitry for regulating (e.g., transforming or converting) electric power. For example, a power supply device can include circuitry for converting an electrical signal with an alternating current to an electrical signal having a direct current (e.g., an AC-to-DC converter). A power supply device can also include control circuitry for determining when the power supply device is coupled with an electronic device. For example, the control circuitry may monitor one or more electrical signals to determine when the devices are coupled. In some embodiments, the control circuitry may monitor one or more sensors to determine when the devices are coupled. The control circuitry can control the operation of the regulating circuitry based on whether or not the power supply device is coupled with the electronic device. For example, the control circuitry can enable and disable the regulating circuitry based on whether or not the power supply device and the electronic device are coupled together. In some embodiments, the regulating circuitry can include a low-power regulating circuitry portion and a high-power regulating circuitry portion, and each portion can be independently activated. 
     The control circuitry can include a processor. In some embodiments, the control circuitry can include a sensor operable to determine when the power supply device is coupled with the electronic device. In some embodiments, the control circuitry can include communications circuitry that can receive data from the electronic device coupled with the power supply device. In some embodiments, a portion of the control circuitry can be located in interface hardware between the power supply device and the electronic device. In some embodiments, the power supply device can also include a connector for coupling with the electronic device, and the control circuitry can include a sensor in the connector for determining when the power supply device is coupled with the electronic device. 
     In some embodiments, the power supply device can include a power storage device coupled with the control circuitry and able to power the control circuitry when the regulating circuitry is not enabled. The power storage device can be rechargeable, and the regulating circuitry can, when enabled, recharge the power storage device. 
     In accordance with some embodiments, a method for providing electric power to an electronic device is provided. The method can include determining when a power supply device is coupled with the electronic device. In some embodiments, the determining can include monitoring a characteristic of a power line in the power supply device. The characteristic can be a voltage level, a current level, or a resistance. In some embodiments, the determining can include monitoring a resistance between a ground potential and a shield of a cable for coupling the power supply device with the electronic device. In some embodiments, the determining can include receiving data from the electronic device. For example, the electronic device can send data to the power supply device to instruct the power supply device to provide power. 
     The method can also include selectively enabling power regulating circuitry based on the determining. The selectively enabling can include selectively enabling the power regulating circuitry when the determining indicates that the power supply device is coupled with the electronic device. The power regulating circuitry can include an AC-to-DC converter. In some embodiments, the method can also include selectively disabling the power regulating circuitry based on the determining. 
     In some embodiments, a power regulating circuitry may include multiple portions, and the selectively enabling can include selectively enabling one or more of the portions based on the determining. The selectively enabling can also include selectively disabling one or more of the portions based on the determining. For example, a low-power portion of a power regulating circuit can be disabled and a high-power portion of a power regulating circuit can be enabled when the determining indicates that the power supply device is coupled with an electronic device. 
     In some embodiments, the method can also include using electric power from a power storage device within the power supply device before the selectively enabling. 
     In accordance with some embodiments, a power supply device is provided. The power supply device can include an AC-to-DC converter that can receive an electric power signal with an alternating current and output an electric power signal with a direct current. The device can also include control circuitry coupled with the converter that can selectively enable the converter when the power supply device is coupled with an electronic device. 
     In accordance with one embodiment, a method for providing electric power to an electronic device is provided. The method can include determining when a power supply device having an AC-to-DC converter is coupled with the electronic device. The method can also include selectively enabling the AC-to-DC converter based on the determining. The selectively enabling can include selectively enabling the AC-to-DC converter when the power supply device is coupled with the electronic device. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The above and other features of the invention, its nature and various advantages will be more apparent upon consideration of the following detailed description, taken in conjunction with the accompanying drawings, in which like reference characters refer to like parts throughout, and in which: 
         FIGS. 1A and 1B  are simplified schematics of electric power supply systems in accordance with various embodiments of the invention; 
         FIG. 2  is a simplified schematic of an electric power supply system in accordance with an embodiment of the invention; 
         FIG. 3  is a simplified schematic of an electric power supply system in accordance with another embodiment of the invention; 
         FIG. 4  is a simplified schematic of an electric power supply system in accordance with another embodiment of the invention; 
         FIGS. 5A and 5B  are simplified schematics of electric power supply systems in accordance with various embodiments of the invention; 
         FIG. 6  is a simplified schematic of an electric power supply system in accordance with yet another embodiment of the invention; 
         FIG. 7  is an illustrative flowchart of a method for providing electric power to an electronic device in accordance with an embodiment of the invention; 
         FIG. 8  is an illustrative flowchart of a method for providing electric power to an electronic device in accordance with another embodiment of the invention; and 
         FIG. 9  is an illustrative flowchart of a method for providing electric power to an electronic device in accordance with another embodiment of the invention. 
     
    
    
     DETAILED DESCRIPTION OF THE DISCLOSURE 
       FIG. 1A  includes power supply system  100  in accordance with various embodiments of the invention. System  100  can include external power source  110 , power supply device  120 , and electronic device  190 . External power source  110  and power supply device  120  can be used to provide electric power to electronic device  190 . For example, power source  110  and power supply device  120  can provide electric power to electronic device  190  for powering circuitry of electronic device  190  or charging a battery of electronic device  190 . 
     As used herein, the term power supply device and the term power supply unit (“PSU”) are interchangeable such that any of the above can be used to refer to a device for coupling an external power source with an electronic device for regulating electric power from the external power source for use by the electronic device. 
     External power source  110  can provide any type of electric power signal. For example, external power source  110  can provide an electric power signal with an alternating current (i.e., “AC” power). In some embodiments, external power source  110  may be an electric power outlet provided in a structure (e.g., a wall outlet), coupled with a power grid, for example. External power source  110  can provide an electric power signal having any reasonable voltage, current limit, AC frequency, or other characteristics. 
     PSU  120  can include connector  121  for coupling with external power source  110 . While  FIG. 1A  shows only raw power line  111  between connector  121  and external power source  110 , it is understood that any suitable interface hardware (e.g., a cable or connector) can be used to couple connector  121  with external power source  110 . Connector  121  can include one or more conductive members (e.g., wires or prongs) for coupling with one or more electric power signals of power source  110 . For example, connector  121  can include two conductive members and each member can couple with a respective component of an AC power signal provided by power source  110 . In another example, connector  121  can include three conductive members and two members can each couple with a respective component of an AC power signal while one member can couple with a ground wire provided by power source  110 . 
     In some embodiments, connector  121  may be keyed such that it can only couple with certain types of external power supplies (e.g., 120 VAC, 60 Hz power supplies or power supplies having a ground wire). 
     PSU  120  can include power regulating circuitry  122  for regulating or converting power from external power source  110  such that it can be used to power electronic device  190 . As used herein, the term regulating can refer to any type of regulating, converting, conditioning, or other type of manipulation performed on raw electric power from an external source to make the power suitable for use by an electronic device. For example, regulating can include converting raw AC power from an external power source to a power signal having direct current (i.e., “DC” power). In another example, regulating can include converting the voltage of raw power from an external power source to a power signal having a suitable voltage for use by an electronic device (e.g., 5 V). In yet another example, regulating can include limiting the current of an electric power signal so that only a certain amount of power can flow to an electronic device. 
     In some embodiments, power regulating circuitry  122  can include multiple portions of circuitry and each portion can output a different power signal. In such embodiments, each power signal can have different characteristics. For example, power regulating circuitry  122  can include low power circuitry for outputting power with a reduced voltage or current limit and high power circuitry for outputting power with a higher voltage or current limit. Each portion of power regulating circuitry  122  can operate independently of the other. For example, power regulating circuitry  122  may be configured so that only one portion can operate at a time. In another example, power regulating circuitry  122  may be configured so that any portion can operate at any time. 
     System  100  can include interface hardware  180  for coupling PSU  120  with electronic device  190 . Interface hardware  180  can, for example, be a cable or a docking station. Interface hardware  180  can include one or more conductive lines for providing electrical signals between PSU  120  and electronic device  190 . In some embodiments, interface hardware may include a physical structure for supporting electronic device  190  (e.g., a docking station). In some embodiments, interface hardware  180  can be completely removable from PSU  120  and electronic device  190 . For example, interface hardware  180  can be a cable that can be used to couple other types of electronic devices together (e.g., an ordinary universal serial bus cable for coupling a peripheral to a personal computer). In other embodiments, interface hardware  180  can be permanently coupled with either PSU  120  or electronic device  190 . Permanently coupling interface hardware  180  with PSU  120  or electronic device  190  can prevent interface hardware  180  from accidentally decoupling or becoming lost. In some embodiments, interface hardware  180  can be permanently coupled with both PSU  120  and electronic device  190 . In some embodiments, interface hardware  180  may include only connector  129  so that connector  191  of electronic device  190  can couple directly with connector  129  of PSU  120 . 
     PSU  120  can include control circuitry  124  for controlling the operation of PSU  120 . Control circuitry  124  can include one or more switches for controlling one or more portions of circuitry within PSU  120 . For example, control circuitry  124  can include a switch for enabling and disabling power regulating circuitry  122 . In some embodiments, control circuitry  124  can include multiple switches such that each switch can enable and disable a different portion of power regulating circuitry  122 . Control circuitry  124  can control power regulating circuitry  122  or a portion thereof by controlling the routing of raw power line  111 . For example, control circuitry  124  can decouple raw power line  111  from regulating circuitry  122  to disable regulating circuitry  122 . In some embodiments, control circuitry  124  can control regulating circuitry  122  by providing one or more control signals to regulating circuitry  122 . In these embodiments, control circuitry  124  may not need to decouple raw power line  111  from regulating circuitry  122  to disable regulating circuitry  122 . 
       FIG. 1B  includes an alternative embodiment of power supply system  100  in accordance with various embodiments of the invention. As shown in  FIG. 1B , control circuitry  124  can be included in interface hardware  180  (e.g., a cable or docking station) between PSU  120  and electronic device  190 . It is understood that control circuitry  124  can be included in PSU  120 , in interface hardware  180 , or distributed between PSU  120  and interface hardware  180  without deviating from the spirit and scope of the invention. 
     Control circuitry  124  can include one or more sensors. Sensors in control circuitry  124  can be used to monitor PSU  120 . In some embodiments, control circuitry  124  can include sensors for determining when PSU  120  is coupled with electronic device  190  via interface hardware  180 . Control circuitry  124  can include a physical switch that is triggered when PSU  120  couples with electronic device  190 . For example, control circuitry  124  can include a microswitch at the end of interface hardware  180  that couples with electronic device  190 . The microswitch can be positioned such that it is physically triggered when interface hardware  180  couples with electronic device  190 . Control circuitry  124  can include a sensor for monitoring an electrical signal between PSU  120  and electronic device  190 . For example, control circuitry  124  can include a capacitive sensor or a hall effect sensor that can be used to determine the amount of current flowing between PSU  120  and electronic device  190 . In this manner, a spike in the current can be indicative of PSU  120  coupling with electronic device  190 . It is understood that control circuitry  124  can include any suitable circuitry or sensor(s) for determining when PSU  120  couples with electronic device  190  without deviating from the spirit and scope of the invention. 
     Control circuitry  124  can use information about PSU  120 , such as whether or not PSU  120  is coupled with electronic device  190 , to control the operation of PSU  120 . Control circuitry  124  can control the operation of power regulating circuitry  122  based on whether or not PSU  120  is coupled with electronic device  190 . For example, control circuitry  124  may disable power regulating circuitry  122  when PSU  120  is not coupled with electronic device  190 . In some embodiments, control circuitry  124  may disable only a portion of power regulating circuitry  122  when PSU  120  is not coupled with electronic device  190 . For example, control circuitry  124  may disable high power circuitry in power regulating circuitry  122  when PSU  120  is not coupled with electronic device  190 . In this manner, PSU  120  can use less electric power by selectively enabling one or more portions of power regulating circuitry  122  when needed. 
     In some embodiments, control circuitry  124  can include a processor. The processor can be any suitable processor for controlling PSU  120  (e.g., a microprocessor). The processor can monitor one or more electrical signals to determine when PSU  120  is coupled with electronic device  190 . In some embodiments, the processor can monitor one or more signals generated by sensors of control circuitry  124 . In some embodiments, the processor can monitor one or more signals passed between PSU  120  and electronic device  190 . For example, the processor can use an analog input to monitor an electric power signal provided by regulating circuitry  122 . Based on monitored information, the processor can provide one or more outputs to control the operation of other circuitry of control circuitry  124 , power regulating circuitry  122 , or any other circuitry in PSU  120 . 
     PSU  120  can include connector  129  for coupling PSU  120  with electronic device  190 . Connector  129  can include one or more conductive members (e.g., wires or prongs) for providing one or more electric power signals of PSU  120  to electronic device  190 . Connector  129  can be keyed such that it can only couple with certain electronic devices. For example, connector  129  can be keyed such that it can only couple with electronic devices that can receive the type of electric power signals output through connector  129 . 
     System  100  can include interface hardware  180  for facilitating the coupling between PSU  120  and electronic device  190 . Interface hardware  180  can include any suitable hardware for coupling PSU  120  with electronic device  190 . For example, interface hardware  180  can include one or more cables. In some embodiments, interface hardware  180  can include a docking station for physically supporting electronic device  190  when it is coupled with PSU  120 . 
     Electronic device  190  can be any electronic device that receives power from PSU  120 . For example, electronic device  190  can be a personal media device, a cellular telephone, or a hybrid device that can both play media and facilitate cellular communications. In some embodiments, electronic device  190  can be a portable media player similar to that sold under the trademark iPod® by Apple Inc. of Cupertino, Calif. In some embodiments, electronic device  190  can be a hybrid portable media player and cellular telephone similar to that sold under the trademark iPhone® by Apple Inc. of Cupertino, Calif. 
     Electronic device  190  can include circuitry  192  for performing one or more functions. For example, electronic device  190  can include circuitry  192  for conducting wireless communications, playing digital media (e.g., songs or videos), playing video games, or performing any other functions. All or a portion of circuitry  192  may be powered by electric power received from PSU  120 . Electronic device  190  can include at least one battery  194  for storing electric power. Each battery  194  may be rechargeable such that it can be charged using electric power from PSU  120 , and the stored power can then be used to power circuitry  192  within electronic device  190  when it is not coupled with PSU  120 . 
     Electronic device  190  can include connector  191  for coupling with interface hardware  180  to receive an electric power signal from PSU  120 . While  FIG. 1A  shows only a line between connector  191  and connector  129 , it is understood that any suitable interface hardware  180  (e.g., cable or connector) can be used to couple connector  191  with connector  129 . In some embodiments, connector  191  can also perform other functions. For example, connector  191  can also be used to communicate with other electronic devices (e.g., other instances of electronic device  190  or personal computers). In this manner, electronic device  190  can use the same connector and some of the same circuitry to receive electric power and communicate with other electronic devices. A Universal Serial Bus (USB) connector is an example of a connector suitable for this purpose. A USB protocol can include four signals: a power signal, a ground signal, and a pair of differential data signals. The power signal is typically referred to as VCC and may maintain a constant 5 VDC. The ground signal is typically referred to as GND and may maintain a constant 0 VDC. Electronic device  190  can receive power through connector  191  over the VCC and GND lines of interface hardware  180  and connector  191 . In some embodiments, electronic device  190  can communicate data through connector  191 . Communicating data can include transmitting information to another electronic device. As used herein, communicating data is different from providing power because communicating data involves relatively low power signals for transmitting information while providing power involves high power signals for powering a device. In embodiments where connector  191  can also be used for both providing power and communicating data, PSU  120  may include corresponding communications circuitry so that PSU  120  can communicate data with electronic device  190 . 
       FIG. 2  includes power supply system  200  in accordance with an embodiment of the invention. System  200  can include external power source  210  (see, e.g., external power source  110 ), PSU  220  (see, e.g., PSU  120 ) and electronic device  290  (see, e.g., electronic device  190 ). Power source  210  and PSU  220  can be used to provide electric power to electronic device  290 . Circuitry provided by PSU  220  can be selectively enabled such that it only operates when electronic device  290  is coupled with PSU  220 . 
     PSU  220  can include power regulating circuitry  222  (see, e.g., regulating circuitry  122 ) for regulating electric power for use by electronic device  290 . Regulating circuitry  222  can an output electric power signal on line  223  that can have characteristics suitable for use by electronic device  290 . For example, an electric power signal on line  223  can be a 5 VDC signal with a current limit determined by regulating circuitry  222 . 
     PSU  220  can include control circuitry  224  (see, e.g., control circuitry  124 ). Control circuitry  224  can be coupled with power regulating circuitry  222 . Control circuitry  224  can provide a control signal on line  227  to regulating circuitry  222  to enable and disable regulating circuitry  222 , for example. Control circuitry  224  can control regulating circuitry  222  based on a connection signal provided to control circuitry  224  via line  225  from connector  229 . A connection signal on connection line  225  can indicate if PSU  220  is coupled with electronic device  290 . By monitoring a connection signal on connection line  225 , control circuitry  224  can selectively enable regulating circuitry  222  when electronic device  290  is coupled with PSU  220 . 
     Indicators provided by the connection signal on connection line  225  can be generated by electronic device  290 . In some embodiments, electronic device  290  can determine that it is coupled with PSU  220  and output an indicator with a connection signal on connection line  225 . In an exemplary USB power supply system, a connection signal on connection line  225  can be a positive leg of the USB differential data signal. In this example, electronic device  290  can drive the positive leg to output a constant high signal as an indicator when electronic device  290  determines that it is coupled with PSU  220 . While the constant high signal is just one example, it is understood that any other indicator or pattern of indicators can be generated by electronic device  290  and transmitted to PSU  220  without deviating from the spirit and scope of the invention. 
     In some embodiments, control circuitry  224  can include communications circuitry for communicating with electronic device  290 . For example, electronic device  290  can request a particular type of electric power (e.g., trickle power for charging a battery in electronic device  290 ) and control circuitry  224  can instruct regulating circuitry  222  to provide the requested type of power. Circuitry for communicating using the USB protocol is an example of suitable communications circuitry in accordance with the invention. 
     In some embodiments, a connection signal on connection line  225  can be generated by a sensor in interface hardware  280  between PSU  220  and electronic device  290 . For example, a connection signal on connection line  225  can be generated by a hall effect or other sensor provided in interface hardware  280  between PSU  220  and electronic device  290 . 
     In some embodiments, control circuitry  224  can include one or more electrical components between raw power line  211  and power regulating circuitry  222  for controlling regulating circuitry  222 . For example, control circuitry  224  can include a power transistor with its gate coupled with connection line  225  and with its source and drain coupled between raw power line  211  and an input of power regulating circuitry  222 . In this manner, the power transistor can provide power to regulating circuitry  222  when a connection signal on connection line  225  is high, for example. In some embodiments, control circuitry  224  may include circuitry to avoid accidentally enabling regulating circuitry  222  when electronic device  290  is not coupled with PSU  220 . For example, control circuitry  224  may include a capacitive element to limit high frequency response such that a temporary voltage spike in a connection signal on connection line  225  does not trigger any response from PSU  220 . 
       FIG. 3  includes power supply system  300  in accordance with an embodiment of the invention. System  300  can include external power source  310  (see, e.g., external power source  110 ), PSU  320  (see, e.g., PSU  120 ) and electronic device  390  (see, e.g., electronic device  190 ). Power source  310  and PSU  320  can be used to provide electric power to electronic device  390 . Circuitry provided by PSU  320  can be selectively enabled such that it only operates when electronic device  390  is coupled with PSU  320 . 
     System  300  can include cable  381  as part of interface hardware  380  for coupling PSU  320  with electronic device  390  (see, e.g., interface hardware  180 ). Cable  381  can be a shielded cable with any number of wires. For example, cable  381  can be a shielded cable with  30  wires and can include a 4-pin USB connector for coupling with PSU  320  and a 30-pin connector for coupling with electronic device  390 . In this example, cable  381  can be used to couple electronic device  390  with PSU  320  or with a computer through a USB port. Connector  329  (see, e.g., connector  129 ) of PSU  320  can couple with cable  381  and couple the shield of cable  381  to chassis ground line  326 . Connector  329  can also route one or more signals within cable  381  to one or more locations in PSU  320 . For example, connector  329  can route circuit ground (e.g., GND) from a line of cable  381  to circuit ground line  325  in PSU  320 . Connector  329  can also route circuit power (e.g., VCC) from a line (not shown in  FIG. 3 ) of cable  381  to circuit power line  323  in PSU  320 . Circuit power may be provided on circuit power line  323 . Circuit power line  323  can be coupled with regulating circuitry  322  (see, e.g., regulating circuitry  122 ) such that electric power output from regulating circuitry  322  can be transmitted through cable  381  to electronic device  390 . 
     Control circuitry  324  (see, e.g., control circuitry  124 ) can be coupled with circuit ground line  325  and chassis ground line  326 . Control circuitry  324  can monitor circuit ground line  325  and chassis ground line  326  to determine when PSU  320  is coupled with electronic device  390 . For example, control circuitry  324  may measure the voltage potential, current flow, or resistance between circuit ground line  325  and chassis ground line  326 . Control circuitry  324  can then provide a control signal on line  327  to selectively enable regulating circuitry  322  to provide power to electronic device  390 . 
     Electronic device  390  can include connector  391  (see, e.g., connector  191 ) for coupling with cable  381 . Connector  391  can route the shield of cable  381  to chassis ground line  396 . Connector  391  can route circuit ground (e.g., GND) from a line of cable  381  to circuit ground line  395 . Electronic device  390  can couple circuit ground line  395  with chassis ground line  396 . Electronic device  390  can include jumper  397  or any other conductive element for coupling the two ground lines together. 
     Coupling circuit ground line  395  with chassis ground line  396  of electronic device  390  can allow control circuitry  324  of PSU  320  to easily determine when electronic device  390  is coupled with PSU  320 . For example, there may be negligible resistance between circuit ground line  325  and chassis ground line  326  of PSU  320  when PSU  320  is coupled with electronic device  390 . Control circuitry  324  can use any suitable method for calculating the resistance between circuit ground line  325  and chassis ground line  326  of PSU  320 . For example, control circuitry  324  can provide a very small voltage potential between the two ground lines and measure the resulting current to calculate the resistance. 
       FIG. 4  includes power supply system  400  in accordance with an embodiment of the invention. System  400  can include external power source  410  (see, e.g., external power source  110 ), PSU  420  (see, e.g., PSU  120 ), and electronic device  490  (see, e.g., electronic device  190 ). Power source  410  and PSU  420  can be used to provide electric power to electronic device  490 . PSU  420  can receive raw electric power from external power source  410  on raw power line  411 . Certain power regulating circuitry of PSU  420  can be selectively enabled such that the certain power regulating circuitry only operates when electronic device  490  is coupled with PSU  420 . PSU  420  can include connector  429  for coupling with electronic device  490 . For example, connector  429  can couple with interface hardware  480  (see, e.g., interface hardware  180 ), and interface hardware  480  can couple with connector  491  of electronic device  490 . 
     PSU  420  can include control circuitry such as processor  424  for controlling PSU  420  (see, e.g., control circuitry  124 ). Processor  424  can be any suitable processor for controlling PSU  420 . For example, processor  424  can be a microprocessor. Processor  424  can control power regulating circuitry in PSU  420 . For example, processor  424  can be coupled with low-power control line  422   a  and high-power control line  423   a . Processor  424  can be coupled with low-power regulating circuitry output  422   b , high-power regulating circuitry output  423   b  and electric power line  440 . Processor  424  can operate using electric power provided on low-power regulating circuitry output  422   b  or electric power provided on high-power regulating circuitry output  423   b . In some embodiments, processor  424  can monitor electric power line  440  to determine when PSU  420  is coupled with electronic device  490 . For example, processor  424  may monitor changes in the voltage of electric power on electric power line  440  or the current flowing through electric power line  440  to determine when PSU  420  is coupled with electronic device  490 . 
     PSU  420  can include low-power regulating circuitry  422  (e.g., a low-power AC-to-DC converter) and high-power regulating circuitry  423  (e.g., a high-power AC-to-DC converter). Processor  424  can be coupled with low-power regulating circuitry  422  and high-power regulating circuitry  423 . For example, processor  424  can provide a control signal to low-power regulating circuitry  422  on low-power control line  422   a  and another control signal to high-power regulating circuitry  423  on high-power control line  423   a . Processor  424  can selectively control (e.g., enable and disable) the operation of low-power regulating circuitry  422  and high-power regulating circuitry  423  using signals on control lines  422   a  and  423   a  respectively. When regulating power, low-power regulating circuitry  422  may consume less power than high-power regulating circuitry  423 . 
     Low-power regulating circuitry  422  can regulate raw power to have a low voltage or low current limit. For example, the voltage and current output by low-power regulating circuitry  422  can be just high enough to power processor  424 . Low-power regulating circuitry  422  may not regulate enough power for powering electronic device  490 . Accordingly, low-power regulating circuitry  422  can power processor  424  so that processor  424  can determine when PSU  420  is coupled with electronic device  490 . Processor  424  can use any suitable method for determining when PSU  420  is coupled with electronic device  490 . In some embodiments, processor  424  can monitor an electric power signal on electric power line  440  to determine when PSU  420  is coupled with electronic device  490 . In some embodiments, processor  424  can monitor one or more sensors to determine when PSU  420  is coupled with electronic device  490 . For example, as discussed above in connection with  FIGS. 1A ,  1 B and  2 , one or more sensors can be provided in PSU  420  or interface hardware  480  for determining when PSU  420  is coupled with electronic device  490 . In some embodiments, processor  424  can monitor one or more electrical signals from connector  429  (see, e.g., connector  129 ) to determine when PSU  420  is coupled with electronic device  490 . 
     Processor  424 , upon determining that PSU  420  is coupled with electronic device  490 , can disable low-power regulating circuitry  422  and enable high-power regulating circuitry  423 . High-power regulating circuitry  423  can regulate raw electric power to have, with respect to low-power regulating circuitry  422 , a higher voltage or a higher current limit. High-power regulating circuitry  423  can provide a sufficient amount of power for powering electronic device  490 . Accordingly, high-power regulating circuitry  423  can regulate power for use by electronic device  490 . Processor  424  can also operate using electric power from high-power regulating circuitry  423  (e.g., if low-power regulating circuitry  422  is disabled). 
     PSU  420  can include programmable switch  432  and programmable switch  433 . Processor  424  can independently control the operation of switches  432  and  433 . Switch  432  and switch  433  can each be a transistor for coupling the output of, respectively, regulating circuitry  422  and regulating circuitry  423  with power line  440 . Processor  424  can use switch  432  to decouple low-power regulating circuitry  422  from power line  440  when circuitry  422  is disabled. Processor  424  can use switch  433  to decouple high-power regulating circuitry  423  from power line  440  when circuitry  423  is disabled. By decoupling disabled power regulating circuitry  422  or  423  from power line  440 , a signal on power line  440  may be more sensitive to PSU  420  coupling with or decoupling from electronic device  490 . In some embodiments, processor  424  can open both switch  432  and switch  433  when PSU  420  is not coupled with electronic device  490 . In these embodiments, processor  424  can operate with power from low-power regulating circuitry output line  422   b  and monitor electric power line  440  to determine when PSU  420  couples with electronic device  490 . In this embodiment, processor  424  may easily determine when PSU  420  is coupled with electronic device  490  because, with switch  432  and switch  433  open, any voltage or current on electric power line  440  must be from electronic device  490 . Once processor  424  determines that PSU  420  is coupled with electronic device  490 , processor  424  can close switch  433  and use high-power control line  423   a  to enable high-power regulating circuitry  423 . Processor  424  can also open switch  432  and disable low-power regulating circuitry  422  once processor  424  determines that PSU  420  is coupled with electronic device  490 . In some embodiments, the advantages of opening switch  432  or switch  433  can include preventing electric power from flowing backwards into the output of regulating circuitry  422  or regulating circuitry  423 . 
     It is understood that switches  432  and  433  can each be replaced by a transistor or any other electronic component suitable for coupling and de-coupling electric power lines without deviating from the spirit and scope of the invention. 
       FIG. 5A  includes power supply system  500  in accordance with an embodiment of the invention. System  500  can include external power source  510  (see, e.g., external power source  110 ), PSU  520  (see, e.g., PSU  120 ) and electronic device  590  (see, e.g., electronic device  190 ). Power source  510  and PSU  520  can be used to provide electric power to electronic device  590 . 
     PSU  520  includes power regulating circuitry  522  (see, e.g., power regulating circuitry  122 ) for regulating a raw electric power signal provided on line  511  from power source  510 . Power regulating circuitry  522  may be configured so that circuitry  522  is always operating when PSU  520  is coupled with power source  510 . 
     PSU  520  can include connector  529  (see, e.g., connector  129 ) for coupling with electronic device  590 . PSU  520  can include electric power line  540  for providing regulated electric power from regulating circuitry  522  to connector  529  and, therefore, electronic device  590 . PSU  520  may include output resistance, modeled by resistor  528  in  FIG. 5 , between electric power line  540  and ground potential. Output resistance can be a provided such that charge does not accumulate on electric power line  540  when PSU  520  is not coupled with electronic device  590 . 
     PSU  520  can include control circuitry such as processor  524  for controlling PSU  520  (see, e.g., control circuitry  124 ). Processor  524  can be any suitable processor for controlling PSU  520 . For example, processor  524  can be a microprocessor. Processor  524  can be coupled with control line  522   a  for controlling power regulating circuitry  522 . Processor  524  can be coupled with output line  522   b  of power regulating circuitry  522 . Processor  524  can operate using electric power from output line  522   b . In some embodiments, processor  524  can monitor output line  522   b  to determine when PSU  520  is coupled with electronic device  590 . For example, processor  524  may monitor changes in the voltage of a signal on output line  522   b  or the current flowing through output line  522   b  to determine when PSU  520  is coupled with electronic device  590 . 
     PSU  520  can include programmable switch  525 . Switch  525  can selectively couple output line  522   b  with electric power line  540 . Processor  524  can be coupled with switch  525  so that processor  524  can control the operation of switch  525 . In some embodiments, switch  525  can be a transistor having its gate coupled with processor  524  and its source and drain between output line  522   b  and electric power line  540 . Switch  525  can be used to decouple output line  522   b  from electric power line  540  when PSU  520  is not coupled with electronic device  590 . Accordingly, power from power regulating circuitry  522  may not be dissipated over output resistance (e.g., resistor  528 ) when PSU  520  is not coupled with electronic device  590 . Using switch  525  to minimize the dissipation of power over output resistance (e.g., resistor  528 ) is advantageous because it can prevent PSU  520  from wasting power. While switch  525  may be open by default, processor  524  can periodically close switch  525  so that processor  524  can measure a signal on output line  522   b  to see if PSU  520  is coupled with electronic device  590 . Processor  524  can close switch  525  at any frequency suitable for monitoring whether PSU  520  has coupled with electronic device  590 . For example, processor  524  can close switch  525  at a frequency of once a second or once every three seconds. If processor  524  determines that PSU  520  has coupled with electronic device  590 , the processor can then keep switch  525  closed so that power from regulating circuitry  522  is provided to electronic device  590  through power line  540 . Processor  524  can keep switch  525  closed until processor  524  determines that PSU  520  is no longer coupled with electronic device  590 . 
       FIG. 5B  includes an alternative embodiment of power supply system  500  in accordance with various embodiments of the invention. In the embodiment shown in  FIG. 5B , processor  524  is coupled with electric power line  540  using monitoring line  526 . Accordingly, processor  524  can monitor electric power line  540 , and therefore determine when PSU  520  is coupled with electronic device  590  without activating switch  525 . The alternative embodiment shown in  FIG. 5B  can, with respect to the embodiment of  FIG. 5A , further conserve power because switch  525  may never be activated unless PSU  520  is coupled with electronic device  590 . 
       FIG. 6  includes power supply system  600  in accordance with an embodiment of the invention. System  600  can include external power source  610  (see, e.g., external power source  110 ), PSU  620  (see, e.g., PSU  120 ), and electronic device  690  (see, e.g., electronic device  190 ). Power source  610  and PSU  620  can be used to provide electric power to electronic device  690 . PSU  620  can couple with electronic device  690  through interface hardware  680  (see, e.g., interface hardware  180 ). Circuitry in PSU  620  can be selectively enabled such that it only operates when electronic device  690  is coupled with PSU  620 . 
     PSU  630  can include power regulating circuitry  622  (see, e.g., power regulating circuitry  122 ) for regulating raw electric power line  611  from power source  610 . The output of power regulating circuitry  622  can be coupled with electric power line  640 . Electric power line  640  can be coupled with connector  629  (see, e.g., connector  129 ) for use by electronic device  690 . 
     PSU  620  can include control circuitry such as processor  624  for controlling PSU  620  (see, e.g., control circuitry  124 ). Processor  624  can be any suitable processor for controlling PSU  620 . For example, processor  624  can be a microprocessor. Processor  624  can be coupled with power regulating circuitry  622  so that processor  624  can control power regulating circuitry. For example, processor  624  can provide a control signal to power regulating circuitry  622  on control line  622   a  so that processor  624  can enable and disable power regulating circuitry  622 . Processor  624  can be coupled with electric power line  640 . Processor  624  can monitor electric power line  640  to determine when PSU  620  is coupled with electronic device  690 . For example, processor  624  may monitor changes in the voltage of a signal on electric power line  640  or the current flowing through electric power line  640  to determine when PSU  620  is coupled with electronic device  690 . 
     PSU  620  can include power storage device  623 . Power storage device  623  can be any device suitable for storing electric power. For example, power storage device  623  can be an electrochemical battery. Power storage device  623  can be coupled with processor  624 . Power storage device  623  can provide a low-power electrical signal to processor  624  for powering processor  624 . Accordingly, processor  624  can operate without enabling power regulating circuitry  622 . When processor  624  determines that PSU  620  is coupled with electronic device  690 , processor  624  can then enable power regulating circuitry  622  to provide electric power to electronic device  690  on power line  640 . While processor  624  uses electric power from power storage device  623  when power regulating circuitry  622  is disabled, processor  624  can use power from electric power line  640  when processor  624  has enabled regulating circuitry  622 . It is understood that circuitry may be provided in PSU  620  for switching the power input of processor  624  between power storage device  623  and electric power line  640 . 
     In some embodiments, PSU  620  can include circuitry (not shown) for disabling processor  624  when PSU  620  is not coupled with power source  610 . One or more sensors can be used to determine when PSU  620  is coupled with power source  610 . In some embodiments, a physical switch can be provided by PSU  620  so that the switch is triggered when PSU  620  coupled with power source  610 . For example, such a switch can be located on the mating surface between PSU  620  and power source  610 . In some embodiments, an electrical sensor can be used to measure the voltage of a signal on raw power line  611  or the current flowing through raw power line  611 . It is understood that any suitable technique can be used to determine when PSU  620  is coupled with power source  610 . When PSU  620  is not coupled with power source  610 , PSU  620  can disable processor  624  to conserve electric power in power storage device  623 . Circuitry in PSU  620  can, for example, disable processor  624  by providing a control signal to processor  624 . In another example, circuitry in PSU  620  can disable processor  624  by decoupling power storage device  623  from processor  624 . 
     In some embodiments, power storage device  623  can be rechargeable. For example, power storage device  623  can be a rechargeable battery. In these embodiments, power storage device  623  can be recharged when power regulating circuitry  622  is operating (i.e., when PSU  620  is coupled with electronic device  690 ). Processor  624  can control the charging of power storage device  623  by coupling electric power line  640  with power storage device  623 . PSU  620  can include circuitry for limiting the current flow from electric power line  640  to power storage device  623  when charging storage device  623 . 
     In some embodiments, power storage device  623  can be charged using power regulating circuitry  622  even when PSU  620  is not coupled with electronic device  690 . PSU  620  may be able to charge power storage device  623  using raw power line  611  from power source  610 . Processor  624  of PSU  620  may be able to control the charging of power storage device  623 . For example, processor  624  may monitor the amount of electric power in storage device  623  and, when the amount drops below a threshold, enable power regulating circuitry  622  for recharging power storage device  623 . To monitor the amount of power in storage device  623 , processor can monitor the voltage of storage device  623 . Charging power storage device  623  when PSU  620  is not coupled with electronic device  690  may be necessary if PSU  620  goes a long time without coupling with electronic device  690 . 
     It is understood that an power storage device similar to power storage device  623  can be used in accordance with any embodiment of the invention. For example, PSU  120  can include a battery for powering control circuitry  124  when power regulating circuitry  122  is not enabled. While the above example relates to PSU  120 , any other PSU described herein can use a power storage device without deviating from the spirit and scope of the invention. 
     While the foregoing system descriptions primarily refer to determining when a PSU couples with an electronic device, it is understood that the same systems can also be used to determine when a PSU decouples from an electronic device. For example, the same indicator or indicators used to determine when a PSU couples with an electronic device can also be used to determine when the PSU decouples from the electronic device. Control circuitry in a PSU may continuously or periodically monitor one or more indicators to determine if the PSU has decoupled from an electronic device. For example, control circuitry can monitor one or more indicators to determine when the PSU is not coupled with any electronic device. Upon determining that a PSU is not coupled with an electronic device, control circuitry may disable power regulating circuitry to conserve power. 
       FIG. 7  is a flowchart of method  700  for providing electric power to an electronic device in accordance with an embodiment of the invention. Method  700  can be performed by a power supply device (see, e.g., PSU  120 ). At step  710 , it can be determined if a power supply device is coupled with an electronic device. This determining can include monitoring one or more signals generated by an electronic device. In some embodiments, this determining can include monitoring one or more sensors. In some embodiments, this determining can include monitoring a characteristic of a power line in the power supply device. The characteristic can be a voltage level, a current level or a resistance. The determining can include, for example, coupling the power line with control circuitry for monitoring the characteristic (see, e.g., PSU  520  with processor  524  and switch  525 ). After the characteristic is monitored, the power line can be decoupled from the control circuitry if it is determined that the power supply device is not coupled with the electronic device. The determining performed at step  710  can include monitoring a resistance between a ground potential and a shield of a cable for coupling the power supply device with the electronic device (see, e.g., control circuitry  324  and cable  381 ). In some embodiments, this determining can include receiving data from the electronic device. For example, control circuitry in a power supply device (see, e.g., control circuitry  124 ) can receive data from an electronic device indicating that the electronic device is coupled with the power supply device. Step  710  can be performed by control circuitry (see, e.g., control circuitry  224 ) in the power supply device. 
     At step  720 , power regulating circuitry within the power supply device can be selectively enabled based on the determining. For example, the power supply device can selectively enable power regulating circuitry if the power supply device is coupled with an electronic device. Power regulating circuitry can include an AC-to-DC converter. In some embodiments, different portion of power regulating circuitry can be independently enabled based on the determining. For example, a high-power regulating circuitry portion can be enabled if the power supply device is coupled with an electronic device, and a low-power regulating circuitry portion can be enabled if the power supply device is not coupled with an electronic device. In some embodiments, a programmable switch may be provided at the output of the high-power regulating circuitry. Method  700  can include opening the switch when the power supply device is not coupled with any electronic device and closing the switch when the power supply device is coupled with the electronic device. 
     In some embodiments, method  700  can include using electric power from a power storage device within the power supply device (see, e.g., power storage device  623 ) before performing step  720 . Method  700  can further include disabling the power regulating circuitry based on the determining performed at step  710 . For example, if the power supply device determines that it is not coupled with any electronic device, the power supply device can disable the power regulating circuitry. 
       FIG. 8  is a flowchart of method  800  for providing electric power to an electronic device in accordance with an embodiment of the invention. Method  800  can be performed by a power supply device (see, e.g., PSU  120 ). At step  810 , the current provided to a connector of the power supply device can be monitored. The connector can be a connector in a power supply device for coupling with an electronic device (see, e.g., connector  129 ). The current can be monitored by control circuitry in the power supply device. At step  820 , a decision can be made as to whether the monitored current stayed below a predetermined threshold current level for at least a predetermined period of time. The predetermined period of time can be any amount of time suitable for averaging the monitored current. Averaging the monitored current over time can prevent a power supply device from reacting to short spikes in current that would otherwise be a false alarm. The predetermined threshold can be selected to be the minimum amount of current an electronic device will draw when coupled with the power supply device. Accordingly, a power supply device can recognize a coupling with an electronic device even if the electronic device is operating using only a minimal amount of current (e.g., operating in standby or trickle charge mode). 
     If the answer to step  820  is yes, method  800  can proceed to step  830 . At step  830 , the power supply device can operate in low power mode. For example, the device can enable low-power regulating circuitry. If the answer to step  820  is no, method  800  can proceed to step  840 . At step  840 , the power supply device can operate in a high power mode. For example, the device can enable high-power regulating circuitry. The output of the power regulating circuitry can be coupled with an output of the power supply device and used by the electronic device. After step  830  or step  840 , method  800  can proceed with step  810  at the beginning of the method. In some embodiments, a delay may be provided after step  830  or step  840  so that a power supply device is not constantly monitoring current. For example, a three second delay may be provided so that the power supply device performs method  800  once every three seconds. 
       FIG. 9  is a flowchart of method  900  for providing electric power to an electronic device in accordance with an embodiment of the invention. Method  900  can be performed by a power supply device with an electric power storage device (see, e.g., PSU  620 ). One or more steps of method  900  can be performed by a processor (see, e.g., processor  624 ) in a power supply device. At step  910 , the power level of an electric power storage device can be determined. For example, the voltage of the electric power storage can be measured to determine the power level. At step  920 , a decision can be made as to whether the determined power level is above a predetermined threshold power level. For example, the voltage level of the power storage device can be compared to a threshold voltage level. If the answer to the decision at step  920  is no, method  900  can proceed with step  930 . At step  930 , power regulating circuitry is activated and charging of the electric power storage device is initiated. The threshold power level used in step  920  can be selected so that it is higher than the minimum power level at which control circuitry (see, e.g., processor  624 ) in the power supply device can function. Accordingly, the threshold power level can be set so that the control circuitry is always functioning when the power supply device is coupled with a power source (see, e.g., power source  610 ). A power supply device can use electric power from the regulating circuitry to charge the electric power device. After step  930 , method  900  may return to step  910  to reevaluate the power level of the power storage device. In some embodiments, a delay may be inserted between step  930  and step  910  so that the power storage device has time to charge before the power level of the storage device is reevaluated. For example, a delay of 10 minutes may be provided so that the power storage device has time to accumulate a substantial charge. 
     If the answer to the decision at step  920  is yes, method  900  can proceed with step  940 . At step  940 , the current provided to a connector of the power supply device can be monitored. The connector can be a connector in a power supply device for coupling with an electronic device (see, e.g., connector  629 ). The current can be monitored by control circuitry in the power supply device. At step  950 , a decision can be made as to whether the monitored current stayed below a predetermined threshold current level for at least a predetermined period of time. The predetermined period of time can be any amount of time suitable for averaging the monitored current. Averaging the monitored current over time can prevent a power supply device from reacting to short spikes in current that would otherwise be a false alarm. The predetermined threshold can be selected to be the minimum amount of current an electronic device will draw when coupled with the power supply device. Accordingly, a power supply device can recognize a coupling with an electronic device even if the electronic device is operating using only a minimal amount of current (e.g., operating in standby or trickle charge mode). 
     If the answer to step  950  is yes, method  900  can proceed to step  960 . At step  960 , the power supply device can deactivate power regulating circuitry. Power regulating circuitry can be deactivated to save electric power when the current measured at step  940  indicates that the power supply device is not coupled with an electronic device. In cases where power regulating circuitry is already deactivated, step  960  may not involve any action on behalf of the power supply device. If the answer to step  950  is no, method  900  can proceed to step  970 . At step  970 , the power supply device can activate power regulating circuitry. The output of the power regulating circuitry can be coupled with an output of the power supply device and used by the electronic device. After step  960  or step  970 , method  900  can proceed with step  910  at the beginning of the method. In some embodiments, a delay may be provided after performing method  900  and before beginning again with step  910  so that a power supply device is not constantly monitoring power levels and current. For example, a three second delay may be provided so that the power supply device performs method  900  once every three seconds. 
     It is to be understood that the foregoing is only illustrative of the principles of the invention, that various modifications can be made by those skilled in the art without departing from the spirit and scope of the invention, and that the invention is limited only by the claims that follow.

Metadata:
Filing Date: 20110429
Publication Date: 20130723
Grant Date: 20130723
Priority Date: 20080926
Inventors: TERLIZZI JEFFREY J.
RABU STANLEY
SANDER WENDELL
MINOO JAHAN
SIMS NICHOLAS AINSLEY
Assignee: APPLE INC
CPC Classifications: [{"code": "H02M7/04", "inventive": true, "first": true, "tree": "[]"}, {"code": "H02M7/04", "inventive": true, "first": true, "tree": "[]"}, {"code": "H02M1/0032", "inventive": false, "first": false, "tree": "[]"}, {"code": "H02M1/0032", "inventive": false, "first": false, "tree": "[]"}, {"code": "H02M1/36", "inventive": true, "first": false, "tree": "[]"}, {"code": "Y02B70/10", "inventive": false, "first": false, "tree": "[]"}, {"code": "H02M1/36", "inventive": true, "first": false, "tree": "[]"}, {"code": "Y02B70/10", "inventive": false, "first": false, "tree": "[]"}]
Family ID: 42057300