PATENT DOCUMENT

Publication Number: US-11183864-B2
Application Number: US-201816125611-A
Country: US
Kind Code: B2

Title: Multimode battery charging

Abstract:
An electronic device may receive or provide power using bidirectional wired and wireless power converters. A bypass path may be included to bypass the battery charger and to allow direct power transfers from a connector of the electronic device to the wireless power converter or from the wireless power converter to the connector of the electronic device. Current limiting and regulation circuitry may also be included.

Claims:
What is claimed is: 
     
       1. An electronic device comprising:
 a connector; 
 a battery charger coupled to the connector, a battery, and a system, wherein the system comprises circuitry of the electronic device; 
 a wireless power converter coupled to the battery charger; and 
 a bypass path coupled between the connector and the wireless power converter to bypass the battery charger, 
 wherein when a voltage received at the connector is determined to be above a first threshold, the bypass path selectively provides power from the connector to the wireless power converter, otherwise the battery charger selectively provides power from the connector to the wireless power converter. 
 
     
     
       2. The electronic device of  claim 1  wherein the battery charger selectively receives power from the connector and selectively provides power to one or more of the system, the battery, and the wireless power converter. 
     
     
       3. The electronic device of  claim 2  wherein the battery charger selectively receives power from one or more of the battery and the wireless power converter and selectively provides power to the connector. 
     
     
       4. The electronic device of  claim 3  wherein the wireless power converter selectively receives power from an accessory and selectively provides power to one or more of the system, the battery, and the battery charger. 
     
     
       5. The electronic device of  claim 4  wherein the wireless power converter selectively receives power from one or more of the battery and the battery charger and selectively provides power to the accessory. 
     
     
       6. The electronic device of  claim 1  wherein the connector is a Universal Serial Bus (USB) Type-C connector. 
     
     
       7. The electronic device of  claim 1  wherein the connector is a Lightning® connector. 
     
     
       8. The electronic device of  claim 1  wherein the bypass path selectively provides power from the wireless power converter to the connector. 
     
     
       9. An electronic device comprising:
 a battery; 
 a connector; 
 a wireless power transmission coil; 
 a battery charger coupled between the battery and the connector, and further coupled to receive a first battery charging signal and a first battery discharging signal, wherein in response to receiving the first battery charging signal, the battery charger receives power from the connector and provides power to the battery, and wherein in response to receiving the first battery discharging signal, the battery charger receives power from the battery and provides power to the connector; 
 a wireless power converter coupled between the battery and the wireless power transmission coil, and further coupled to receive a second battery charging signal and a second battery discharging signal, wherein in response to receiving the second battery charging signal, the wireless power converter receives power from the wireless power transmission coil and provides power to the battery, and wherein in response to receiving the second battery discharging signal, the wireless power converter receives power from the battery and provides power to the wireless power transmission coil; and 
 a bypass path coupled between the connector and the wireless power converter, and further coupled to receive a bypass signal, wherein in response to receiving the bypass signal the bypass path transfers power between the connector and the wireless power converter, 
 wherein in response to the battery charger receiving the first battery charging signal simultaneously with the wireless power converter receiving the second battery charging signal, power received from the connector and power received from the wireless power transmission coil are simultaneously provided to the battery. 
 
     
     
       10. The electronic device of  claim 9  wherein the battery charger comprises a first power output stage having an input coupled to the connector and an output coupled to a first terminal of a first inductor, the first inductor having a second terminal coupled to the battery. 
     
     
       11. The electronic device of  claim 10  wherein the wireless power converter comprises:
 a second power output stage having an input coupled to the battery and an output coupled to a first terminal of a first capacitor, the first capacitor having a second terminal coupled to a first terminal of the wireless power transmission coil; and 
 a third power output stage having an input coupled to the battery and an output coupled to a first terminal of a second capacitor, the second capacitor having a second terminal coupled to a second terminal of the wireless power transmission coil. 
 
     
     
       12. The electronic device of  claim 11  wherein the bypass path comprises two transistors coupled to have back-to-back body diodes. 
     
     
       13. The electronic device of  claim 9  wherein the connector is a Universal Serial Bus (USB) Type-C connector. 
     
     
       14. The electronic device of  claim 9  wherein the connector is a Lightning® connector. 
     
     
       15. An electronic device comprising:
 a battery; 
 a connector; 
 a wireless power transmission coil; 
 a battery charger coupled between the battery and the connector, and further coupled to selectively transfer power from the connector to the battery, and to selectively transfer power from the battery to the connector; 
 a wireless power converter coupled between the battery and the wireless power transmission coil, and further coupled to selectively transfer power from the wireless power transmission coil to the battery, and to selectively transfer power from the battery to the wireless power transmission coil; and 
 a bypass path configured to selectively transfer power from the connector to the wireless power converter while the battery charger selectively transfers power from the connector to the battery. 
 
     
     
       16. The electronic device of  claim 15  wherein the bypass path is further coupled to selectively transfer power from the wireless power converter to the connector. 
     
     
       17. The electronic device of  claim 16  wherein each of the battery charger and the wireless power converter are further coupled to selectively transfer power to system circuitry in the electronic device. 
     
     
       18. The electronic device of  claim 15  wherein the connector is a Universal Serial Bus (USB) Type-C connector. 
     
     
       19. The electronic device of  claim 15  wherein the connector is a Lightning® connector.

Description:
CROSS-REFERENCES TO RELATED APPLICATIONS 
     This application is a nonprovisional of United States provisional patent application No. 62/667,896, filed May 7, 2018, which is incorporated by reference. 
     BACKGROUND 
     Battery powered electronic devices may include rechargeable batteries. These battery powered electronic devices may also include power converters that receive power from external sources and in turn provide power to internal circuitry. These external sources may be chargers or other types of electronic devices. Many of these battery powered electronic devices need to be charged on a regular basis. Accordingly, what is needed are battery powered electronic devices that have an increased flexibility as to how they may be charged. 
     SUMMARY 
     Accordingly, embodiments of the present invention may provide charging circuitry for electronic devices, where the charging circuitry provides increased flexibility in charging the electronic devices. An illustrative embodiment of the present invention may include both a battery charger and a wireless power converter. The battery charger may include one or more buck or boost converters, though other types of power converters may be included as well. The battery charger may receive a voltage from an external source via a connector of the electronic device and use the received power to charge a battery and to supply power to circuitry in the electronic device. The external source may be a charger, host device, or other electronic device. The wireless power converter may receive wireless power from a wireless charger or other accessory device. The wireless power converter may include a rectifier to convert received inductive power to DC power, and then use the DC power to charge the battery and to supply power to system circuitry in the electronic device. 
     In these and other embodiments of the present invention, one or both of these wired and wireless power converters may be bidirectional circuits. That is, the battery charger may receive or provide wired power, while the wireless power converter may receive or provide wireless power. For example, the battery charger may receive a voltage from an external source via a connector and use the received power to charge a battery and to supply power to system circuitry in the electronic device. The battery charger may alternatively receive power from the battery and provide power to the connector of the electronic device. The wireless power converter may receive wireless power from a charger or other accessory device, convert the received wireless power to DC power, and then use the DC power to charge the battery and to supply power to circuitry in the electronic device. The wireless power converter may instead receive DC power from the battery, convert the DC power from the battery to wireless power, and transmit wireless power to an accessory device. The wireless power converter may include one or more driver stages to transmit the wireless power. In these and other embodiments of the present invention, the driver stages used to transmit power may operate as a rectifier when receiving wireless power. 
     In these and other embodiments of the present invention, power may be provided directly from the connector of the electronic device to the wireless power converter. Accordingly, embodiments of the present invention may include a bypass path. The bypass path may receive power from the connector of the electronic device and provide it to the pair of drivers in the wireless power converter, where the wireless power converter converts the power received from the connector and wirelessly provides it to an accessory device. This is particularly useful when a relatively high voltage, for example 9 or 15 volts, is received at the connector of the electronic device. 
     In these and other embodiments of the present invention, power may be provided directly from the wireless power converter to the connector of the electronic device. Accordingly, the bypass path may be a bidirectional path. Power received at the rectifier in the wireless power converter may be directly provided to the connector of the electronic device. This power may then be provided to an external device, such as a host or other electronic device. 
     In these and other embodiments of the present invention, power may be transferred among two or more devices, including an electronic device, in a highly flexible manner. In a first example, power may be received from a connector in an electronic device and used to charge a battery and provide power to circuitry in the electronic device (referred to as the system herein) and to further provide wireless power to an accessory. Specifically, power may be received at a connector of the electronic device from a host or other electronic device. This power may be received by a buck or other power converter in the battery charger. Some of this power may be provided to the battery and system, while the remainder may be provided to a boost converter in the battery charger, which may then provide power to the wireless power converter. One or more drivers in the wireless power converter may generate an alternating current through a first wireless power transmission coil. This wireless power may be received by a second wireless power transmission coil in an accessory. A rectifier across the second wireless power transmission coil in the accessory may receive the wireless power, convert the wireless power, and provide power to the accessory. 
     In a second example, wireless power may be received by an electronic device from an accessory and used to charge a battery and provide power to the system in the electronic device. Specifically, power may be provided by one or more drivers in an accessory, which may generate an alternating current through a first wireless power transmission coil. This wireless power may be received by a second wireless power transmission coil in the electronic device. A rectifier in the wireless power converter may receive the wireless power and provide power to a buck converter in a battery charger. The buck converter may provide power to the battery and the system. 
     In a third example, power may be received from a host or other electronic device or charger, and used to charge a battery and power the system in an electronic device. Specifically, power may be received at a connector of the electronic device from a host or other electronic device or charger. This power may be received by a buck or other power converter in the battery charger. More specifically, in these and other embodiments of the present invention, the battery charger may include a two-phase buck or other type of converter, and this buck or other converter may convert the received power and provide it to the battery and system for a fast charging. 
     In a fourth example, power may be provided by a battery of an electronic device and used to provide wireless power to an accessory. Specifically, power may be received from the battery by a boost or other converter in the battery charger. The boost converter may provide power to a wireless power converter. One or more drivers in the wireless power converter may generate an alternating current through a first wireless power transmission coil. This wireless power may be received by a second wireless power transmission coil in an accessory. A rectifier across the wireless power transmission coil in the accessory may receive the wireless power and provide power to the accessory. 
     In a fifth example, power received at a connector of an electronic device may be used to provide power to a battery and system of the electronic device. Power may also be provided wirelessly from the electronic device to an accessory. Specifically, power may be received at a connector of the electronic device from a host or other electronic device or charger. This power may be provided to a two-phase buck or other power converter in the battery charger. The output power from the buck converter may be provided to the battery and system. Power from the connector may also be provided to a wireless power converter. This power may be provided to the wireless power converter directly through a bypass path that connects the connector of the electronic device to the wireless power converter. One or more drivers in the wireless power converter may generate an alternating current through a first wireless power transmission coil. This wireless power may be received by a second wireless power transmission coil in an accessory. A rectifier across the coil may receive the wireless power and provide power to the accessory. 
     In a sixth example, both wired and wireless power may be received by an electronic device and used to charge a battery and provide power to the system of the electronic device. Specifically, power may be received at a connector of the electronic device from another electronic device or charger device. This power may be received by a buck or other power converter in the battery charger. The output power of the buck converter may be provided to the battery and system. At the same time, power may be provided by one or more drivers in an accessory, which may generate an alternating current through a first wireless power transmission coil. This wireless power may be received by a second wireless power transmission coil in the electronic device. A rectifier in the wireless power converter may receive the wireless power and provide power a second buck converter, which may also provide power to the battery and the system. This combined current from wired and wireless sources may speed the rate of charging of the battery. 
     In a seventh example, wireless power may be received from an accessory and wired power may be provided via a connector of an electronic device. Specifically, power may be provided by one or more drivers in a first accessory, which may generate an alternating current through a first wireless power transmission coil. This wireless power may be received by a second wireless power transmission coil in the electronic device. A rectifier in the wireless power converter may receive the wireless power and provide this power to a buck converter in a battery charger. The output of the buck converter may be used to charge a battery and to provide power to the system of the electronic device. Power may also be received from the battery and provided to a boost converter in the battery charger. The output of the boost converter may provide power to a connector of the electronic device. Power may then be received from the connector of the electronic device by a second accessory. 
     These and other embodiments of the present invention may provide current limiting circuitry. For example, current in the battery charger may be monitored. When this current is excessive, the power path through the battery charger may be disabled. In these and other embodiments of the present invention, power transfer in the bypass path may be disabled when current in the battery charger is excessive. In these and other embodiments of the present invention, power in the wireless power converter may be disconnected when current in the wireless power converter is over an allowed portion of the current in the battery charger. 
     These and other embodiments of the present invention may provide current regulation circuitry. For example, in the first and fifth examples above, where power from the connector of the electronic device is provided to both the battery and the wireless power converter, power to either or both of the battery or wireless power converter may be regulated to ensure that the wireless power converter has sufficient current. In the seventh example above, where power from the wireless power converter is provided to both the battery and the connector of the electronic device, current to either or both the battery and the connector of the electronic device may be regulated to ensure that each has sufficient power. This regulation may be done in various ways. For example, the duty cycle of control signals at the gates of transistors in the various boost or buck circuits may be varied to effectively vary their impedance. 
     In these and other embodiments of the present invention, the current regulation may follow various procedures and policies. For example, a priority may be that the wireless power converter receive sufficient current to provide a certain number of watts of wireless power, that the system receive a certain amount of current, while a remainder may go to the battery. 
     These and other embodiments of the present invention may not support each and every one of the configurations disclosed herein. That is, these and other embodiments of the present invention may support a subset of the functions disclosed herein. Also, in these and other embodiments of the present invention, other power transfer configurations may be possible. For example, power may be provided from the battery to the connector of the electronic device through either or both battery charger and the bypass path. In another example, power may also be provided from the battery to both the connector and the wireless power converter of the electronic device. 
     The battery charger, wireless power converter, and bypass path may be configured for these various operations in different ways. For example, one or more connection or orientation detection contacts in the connector may be used to determine when an external host or other electronic device or charger is connected to the battery charger via the connector. These connection or orientation detection contacts may be coupled to circuitry (not shown) that may be used to determine whether a connected device should provide power to one or more of the system, battery, or wireless power converter, or whether the connected device should receive power from one or more of these sources. Circuitry connected to the wireless power converter may determine when an external accessory or charger is inductively connected to the wireless power converter. This circuitry may further determine whether an inductively connected device should provide power to one or more of the system, battery, or battery charger, or whether the inductively connected device should receive power from one or more of these sources. Circuitry connected to the bypass path may determine whether a power supply received at the connector is sufficient to directly power the wireless power converter and may connect these circuits accordingly. This circuitry may also determine whether the wireless power converter may directly provide power to the connector, and may connect these circuits accordingly. 
     These and other embodiments of the present invention may provide a battery charger having a number of converters For example, the battery charger may include a first buck converter to receive power from the connector and provide power to the battery and system. A second buck converter may be included to also receive power from the connector and provide power to the battery and system. A third buck converter may be included to receive power from the wireless power converter and provide power to the battery and system. A first boost converter may be included to receive power from the battery and provide power to the connector, while a second boost converter may be included to receive power from the battery and provide power to the wireless power converter. These and other embodiments of the present invention may simplify the circuitry of battery charger by reconfiguring some or all of these power converters in the various examples of power transfer configurations shown herein. These reconfigurations may be done by configuring switches and altering transistor drive voltages. For example, a first power converter may be coupled between the connector and battery. The first power converter may operate as a buck converter when providing power from the connector to the battery and system, and as a boost converter when providing power from the battery to the connector. The second power converter may operate as a buck converter when providing power from the connector to the battery and system, as a buck converter when providing power from the wireless power converter to the battery and system, and as a boost converter when providing power from the battery to the wireless power converter. 
     These and other embodiments of the present invention may provide a wireless power converter having one or more driving circuits for providing wireless power and a rectifier for receiving wireless power. These and other embodiments of the present invention may simplify the circuitry of the battery charger by using the driver circuits of the power transmitting circuit as the rectifier in the power receiving circuit. 
     These and other embodiments of the present invention may provide charging circuitry that may be located in various types of devices, such as portable computing devices, tablet computers, desktop computers, laptops, all-in-one computers, cellular phones, smart phones, media phones, storage devices, portable media players, wearable computing devices, navigation systems, monitors, power supplies, adapters, remote control devices, chargers, and other devices. 
     Various embodiments of the present invention may incorporate one or more of these and the other features described herein. A better understanding of the nature and advantages of the present invention may be gained by reference to the following detailed description and the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  illustrates an example of an electronic system according to an embodiment of the present invention; 
         FIG. 2  illustrates an example of a battery charger and bypass path according to an embodiment of the present invention; 
         FIG. 3  illustrates another example of a battery charger and bypass path according to an embodiment of the present invention; 
         FIG. 4  illustrates another example of a battery charger and bypass path according to an embodiment of the present invention; 
         FIG. 5  illustrates an example of a wireless power converter cording to an embodiment of the present invention; 
         FIG. 6  illustrates an example of a wireless power converter for an accessory according to an embodiment of the present invention; 
         FIG. 7  is a simplified example of a power transfer system of an electronic device and an accessory according to an embodiment of the present invention; 
         FIG. 8  is a flow chart showing a first example of power transfer according to an embodiment of the present invention; 
         FIG. 9  is a simplified schematic of a power transfer system configured for the first example according to an embodiment of the present invention; 
         FIG. 10  is a flow chart showing a second example of power transfer according to an embodiment of the present invention; 
         FIG. 11  is a simplified schematic of a power transfer system configured for the second example according to an embodiment of the present invention; 
         FIG. 12  is a flow chart showing a third example of power transfer according to an embodiment of the present invention; 
         FIG. 13  is a simplified schematic of a power transfer system configured for the third example according to an embodiment of the present invention; 
         FIG. 14  is a flow chart showing a fourth example of power transfer according to an embodiment of the present invention; 
         FIG. 15  is a simplified schematic of a power transfer system configured for the fourth example according to an embodiment of the present invention; 
         FIG. 16  is a flow chart showing a fifth example of power transfer according to an embodiment of the present invention; 
         FIG. 17  is a simplified schematic of a power transfer system configured for the fifth example according to an embodiment of the present invention; 
         FIG. 18  is a flow chart showing a sixth example of power transfer according to an embodiment of the present invention; 
         FIG. 19  is a simplified schematic of a power transfer system configured for the sixth example according to an embodiment of the present invention; 
         FIG. 20  is a flow chart showing a seventh example of power transfer according to an embodiment of the present invention; and 
         FIG. 21  is a simplified schematic of a power transfer system configured for the seventh example according to an embodiment of the present invention. 
     
    
    
     DESCRIPTION OF EXEMPLARY EMBODIMENTS 
       FIG. 1  illustrates an example of an electronic system according to an embodiment of the present invention. This figure, as with the other included figures, is shown for illustrative purposes and does not limit other the possible embodiments of the present invention or the claims. 
     This figure includes electronic device  100 . Electronic device  100  may include a connector  112  that may connect to and bidirectionally exchange wired power with an external charger, host device, or other type of electronic device. Battery charger  110  may provide or receive power from battery  150 . Battery charger  110  may also supply power to system  130 . System  130  may comprise some or all of the electronic circuitry of electronic device  100 . Battery charger  110  may also bidirectionally exchange power with wireless power converter  120 . Wireless power converter  120  may wirelessly and bidirectionally exchange power with accessory  160  via wireless path  170 . Bypass path  140  may provide a bidirectional pathway around battery charger  110  from connector  112  to wireless power converter  120 . 
     Connector  112  may include contacts for POWER SOURCE  1  and ground. Other contacts for other power supplies, signals, connection detection, orientation detection, bias lines, or other signals or voltages, may be included in connector  112 . Connector  112  may be a universal serial bus (USB) Type C, other USB, lightning, thunderbolt, or other type of connector. 
     Battery charger  110 , wireless power converter  120 , and bypass path  140  may each be bidirectional circuits. This may allow power from either or both a device connected to connector  112  and accessory  160  to provide power to, or receive power from, electronic device  100 . Examples of several possible power-sharing configurations are shown below. 
     Various circuits may be used for battery charger  110 , wireless power converter  120 , bypass path  140 , and the wireless circuitry in accessory  160 . Examples are shown in the following figures. 
       FIG. 2  illustrates a battery charger and bypass path according to an embodiment of the present invention. In this example, a power supply voltage at POWER SOURCE  1  may be received from a host or other electronic device or charger, or provided to a host or other electronic device, via connector  112  or other wired connection as shown in  FIG. 1 . Connector  112  may be a USB Type-C, USB Type-A, lightning, or other type of connector. In these and other embodiments of the present invention, the voltage at POWER SOURCE  1  may instead be received from, or provided to, a wireless power converter or other wireless power source or receiver. Switch S 1 , which may include transistors M 16  and M 17  in a back-to-back configuration, may selectively connect POWER SOURCE  1  to node VA and to power converter transistors M 1  and M 2 . Power converter transistors M 1  and M 2  and inductor L 2  may be used as a buck converter when providing power from POWER SOURCE  1  to battery  150  and system  130 , and as a boost converter when providing power from battery  150  to node POWER SOURCE  1 . In both of these configurations, switches S 1  and S 4  may be closed. Transistors M 1 -M 2  may be driven at their gates by signals V 1 -V 2 . Signals V 1 -V 2  may be non-overlapping pulse-width modulated signals which may generate currents in L 2 . Switch S 2 , which may include transistors M 14  and M 15  in a back-to-back configuration, may selectively couple the voltage on node VA to node VB and the power converter transistors M 3  and M 4 . The power converter transistors M 3  and M 4  and inductor L 1  may operate as a buck converter when providing power from connector  112  to battery  150  and system  130  (S 1 , S 2 , and S 4  closed), as a buck converter when providing power from wireless power converter  120  to battery  150  and system  130  (S 3  and S 4  closed), and as a boost converter when providing power from battery  150  to wireless power converter  120  (S 3  and S 4  closed.) Transistors M 3 -M 4  may be driven at their gates by signals V 3 -V 4 . Signals V 3 -V 4  may be non-overlapping pulse-width modulated signals which may generate currents in inductor L 1 . The currents in L 1  and L 2  may generate the output voltage VOUT. The output voltage VOUT may be used to provide power to system  130 , as shown in  FIG. 1 . Switch S 4 , which may include transistor M 19 , may selectively connect the output voltage VOUT to the battery at terminal VBATT. Switch S 3 , which may include transistor M 18 , may selectively connect the voltage at VB to POWER SOURCE  2 , which may be received or provided by wireless power converter  120 . In these and other embodiments of the present invention, POWER SOURCE  2  may instead receive power from, or provide power to, a connector such as a USB Type-C, USB Type-A, lightning, or other wired connection. 
     In this example, bypass path  140  may comprise switches S 1 , S 2 , and S 3 . These switches may be closed in order to provide power from POWER SOURCE  1  at connector  112  directly to POWER SOURCE  2 , or from POWER SOURCE  2  directly to POWER SOURCE  1  at connector  112 . 
     In these and other embodiments of the present invention, it may be undesirable to provide a current pathway directly from a first power source to a second power source. Accordingly, either or both of the switches S 1  or S 2  may include two transistors arranged to have back-to-back body diodes. These back-to-back body diodes may allow a switch to be configured with one transistor on and conducting, while a second transistor may be off and its body diode may be conducting. This may allow a switch to pass current in a forward direction and to prevent an undesirable reverse current flow. For example, it may be undesirable to provide a high voltage received on POWER SOURCE  2  from being provided to POWER SOURCE  1 . Accordingly, in switch S 2 , transistor M 14  may be off while transistor M 15  is on. This may allow current to flow from POWER SOURCE  1  to POWER SOURCE  2 , while not allowing current to flow from POWER SOURCE  2  to POWER SOURCE  1 . 
     In these and other embodiments of the present invention, a battery charger may include current limiting circuitry. For example, current being provided to the output voltage VOUT may be monitored in one or more of the driver transistors M 1 -M 4 . When the monitored current is excessive, one or more of the switches S 1 , S 2 , S 3 , or S 4 , may be opened. In these and other embodiments of the present invention, transistors M 1  and M 2  may limit a current drawn from the host device through connector  112 . Transistors M 1  and M 2  may be alternatively referred to as a charger and may be used to ensure that the current drawn does not exceed a specification, such as one of the Universal Serial Bus specifications. 
     In these and other embodiments of the present invention, a battery charger may include current regulating circuitry. For example, power may be received at POWER SOURCE  1  and provided both to the battery and to wireless power converter  120  via POWER SOURCE  2 . In such a case, current in the various power converters may be monitored. Based on the monitored current, the impedance of one or more power converters may be varied by adjusting the duty cycles of their gate signals to ensure that wireless power converter  120  has sufficient current for proper operation. 
     In these examples, battery charger  110  may receive or provide power at nodes POWER SOURCE  1  and POWER SOURCE  2 . Power at either or both of these nodes may be received from, or provided to, a wired connection, such as connector  112  of electronic device  100 , or other wired connection. Power at either or both of these nodes may instead be received from, or provided to, a wireless source or receiver, such as wireless power converter  120  or other wireless source or receiver. 
       FIG. 3  illustrates another example of a battery charger and bypass path according to an embodiment of the present invention. In this example, a power supply voltage may be received at POWER SOURCE  1  from a host or other electronic device or charger, or provided to a host or other electronic device, via connector  112  or other wired connection as shown in  FIG. 1 . Connector  112  may be a USB Type-C, USB Type-A, lightning, or other type of connector. In these and other embodiments of the present invention, the voltage at POWER SOURCE  1  may instead be received from, or provided to, a wireless power converter or other wireless power source or receiver. Switch S 1 , which may include transistor M 16 , may selectively connect POWER SOURCE  1  to node VA and to power converter transistors M 1  and M 2 . In this example, power converter transistors M 1  and M 2  and inductor L 2  may be used as a buck converter when providing power from POWER SOURCE  1  to battery  150  and system  130 , and as a boost converter when providing power from battery  150  to node POWER SOURCE  1 . In both of these configurations, switches S 1  and S 4  may be closed. Transistors M 1 -M 2  may be driven at their gates by signals V 1 -V 2 . Signals V 1 -V 2  may be non-overlapping pulse-width modulated signals which may generate currents in L 2 . Switch S 2 , which may include transistors M 14  and M 15  connected in a back-to-back configuration, may selectively couple node POWER SOURCE  1  to node VB and the power converter transistors M 3  and M 4 . The power converter transistors M 3  and M 4  and inductor L 1  may operate as a buck converter when providing power from the connector to battery  150  and system  130  (S 2  and S 4  closed), as a buck converter when providing power from wireless power converter  120  to battery  150  and system  130  (S 3  and S 4  closed), and as a boost converter when providing power from battery  150  to wireless power converter  120  (S 3  and S 4  closed.) Transistors M 3 -M 4  may be driven at their gates by signals V 3 -V 4 . Signals V 3 -V 4  may be non-overlapping pulse-width modulated signals which may generate currents in inductor L 1 . The currents in inductors L 1  and L 2  may generate the output voltage VOUT. The output voltage VOUT may be used to provide power to system  130 , as shown in  FIG. 1 . Switch S 4 , which may include transistor M 19 , may selectively connect the output voltage VOUT to the battery at terminal VBATT. Switch S 3 , which may include transistor M 18 , may selectively connect the voltage at VB to POWER SOURCE  2 , which may be received from, or provided to, wireless power converter  120  or other wireless power source or receiver. In these and other embodiments of the present invention, POWER SOURCE  2  may instead receive power from, or provide power to, a connector, such as a USB Type-C, USB Type-A, lightning, or other wired connection. 
     In this example, bypass path  140  may comprise switches S 2  and S 3 . These switches may be closed in order to provide power from POWER SOURCE  1  at connector  112  directly to POWER SOURCE  2 , or from POWER SOURCE  2  directly to POWER SOURCE  1  at connector  112 . 
     Again, it may be undesirable to provide a current pathway from a first power source to a second power source. Accordingly, one or more of the switches S 2  and S 4  may include two transistors arranged to have back-to-back body diodes. These back-to-back body diodes may allow a switch to be configured with one transistor to be on and conducting, while a second transistor may be off and its body diode may be conducting. This may allow a switch to pass current in a forward direction and to prevent an undesirable reverse current flow. For example, it may be undesirable to provide a high voltage received on POWER SOURCE  2  from being provided to POWER SOURCE  1 . Accordingly, in switch S 2 , transistor M 14  may be off while transistor M 15  is on. This may allow current to flow from node POWER SOURCE  1  to POWER SOURCE  2 , while not allowing current to flow from POWER SOURCE  2  to POWER SOURCE  1 . 
     In these and other embodiments of the present invention of the present invention, a battery charger  110  may include current limiting circuitry. For example, current being provided to the output voltage VOUT may be monitored in one or more of the power converter transistors M 1 -M 4 . When the monitored current is excessive, one or more of the switches S 1 , S 2 , or S 4 , may be opened. 
     In these and other embodiments of the present invention, battery charger  110  may include current regulating circuitry. For example, power may be received at POWER SOURCE  1  and provided both to battery  150  and to wireless power converter  120  via POWER SOURCE  2 . In such a case, current in any or all of the power converters may be monitored. Based on the monitored currents, the impedance of one or more power converters may be varied by adjusting the duty cycles of their gate signals to ensure that wireless power converter  120  has sufficient current for proper operation. 
       FIG. 4  illustrates another example of a battery charger and bypass path according to an embodiment of the present invention. In this example, a power supply voltage at POWER SOURCE  1  may be received from a host or other electronic device or charger, or provided to a host or other electronic device, via connector  112  or other wired connection as shown in  FIG. 1 . Connector  112  may be a USB Type-C, USB Type-A, lightning, or other type of connector. In these and other embodiments of the present invention, POWER SOURCE  1  may instead be received from, or provided to, a wireless power converter or other wireless power source or receiver. A boost converter (not shown) may be situated between connector  112  and battery charger  110 . Switch S 1 , which may include transistor M 16 , may selectively connect POWER SOURCE  1  to node VA and to power converter transistors M 1  and M 2 . In this example, power converter transistors M 1  and M 2  and inductor L 2  may be used as a buck converter when providing power from POWER SOURCE  1  to battery  150  and system  130 , and as a boost converter when providing power from battery  150  to POWER SOURCE  1 . In both of these configurations, switches S 1  and S 4  may be closed. Transistors M 1 -M 2  may be driven at their gates by signals V 1 -V 2 . Signals V 1 -V 2  may be non-overlapping pulse-width modulated signals which may generate currents in L 2 . Switch S 2 , which may include transistor M 14 , may selectively couple node POWER SOURCE  1  to node VB and the power converter transistors M 3  and M 4 . The power converter transistors M 3  and M 4  and inductor L 1  may operate as a buck converter when providing power from the connector to battery  150  and system  130  (S 2  and S 4  closed). The power converter transistors M 3  and M 4  and inductor L 1  may operate as a buck converter when providing power from wireless power converter  120  to battery  150  and system  130  (S 5  and S 4  closed), and as a boost converter when providing power from battery  150  to wireless power converter  120  (S 5  and S 4  closed.) Transistors M 3 -M 4  may be driven at their gates by signals V 3 -V 4 . Signals V 3 -V 4  may be non-overlapping pulse-width modulated signals which may generate currents in inductor L 1 . The currents in inductor L 1  and L 2  may generate the output voltage VOUT. The output voltage VOUT may be used to provide power to system  130 , as shown in  FIG. 1 . Switch S 4 , which may include transistor M 19 , may selectively connect the output voltage VOUT to the battery at terminal VBATT. Switch S 3 , which may include transistor M 18 , may selectively connect the voltage at VB to POWER SOURCE  2 , which may be received from or provided to wireless power converter  120 . In these and other embodiments of the present invention, node POWER SOURCE  2  may instead receive power from, or provide power to, a connector, such as a USB Type-C, USB Type-A, lightning or other wired connection. 
     Switch S 5 , which may include transistor M 20 , may couple POWER SOURCE  2  to the power converter transistor M 13 . Power converter transistor M 13  may be used with power converter transistor M 4  to form a buck or a boost converter. In these and other embodiments of the present invention, both M 13  and M 3  may be used along with M 4  to form a buck or a boost converter. 
     In this example, bypass path  140  may comprise switches S 2  and S 3 . These switches may be closed in order to provide power from POWER SOURCE  1  at connector  112  directly to POWER SOURCE  2 , or from POWER SOURCE  2  directly to POWER SOURCE  1  at connector  112 . 
     Again, it may be undesirable to provide a current pathway from a first power source to a second power source. Accordingly, one or more of the switches S 2  and S 3  may be formed using two transistors arranged to have back-to-back body diodes. These back-to-back body diodes may allow a switch to be configured with one transistor to be on and conducting, while a second transistor may be off and its body diode may be conducting. This may allow a switch to pass current in a forward direction and to prevent an undesirable reverse current flow. For example, it may be undesirable to provide a high voltage received on POWER SOURCE  2  from being provided to POWER SOURCE  1 . Accordingly, in switch S 2 , transistor M 14  may be off while transistor M 18  in switch S 3  is on. This may allow current to flow from node POWER SOURCE  1  to POWER SOURCE  2 , while not allowing current to flow from POWER SOURCE  2  to POWER SOURCE  1 . 
     In these and other embodiments of the present invention of the present invention, battery charger  110  may include current limiting circuitry. For example, current being provided to the output voltage VOUT may be monitored in one or more of the power converter transistors M 1 -M 4 . When the monitored current is excessive, one or more of the switches S 1 , S 2 , or S 4 , may be opened. 
     In these and other embodiments of the present invention, a battery charger may include current regulating circuitry. For example, power may be received at POWER SOURCE  1  and provided both to battery  150  and to wireless power converter  120  via POWER SOURCE  2 . In such a case, current in any or all of the power converters may be monitored. Based on the monitored currents, the impedance of one or more of the power converters may be varied by adjusting the duty cycles of their gate signals to ensure that wireless power converter  120  has sufficient current for proper operation. 
     In these and other embodiments of the present invention, the current regulation may follow various procedures and policies. For example, a priority may be that wireless power converter  120  receive sufficient current to provide a certain number of watts of wireless power, that a certain amount go to system  130 , while a remainder may go to battery  150 . 
     These and other embodiments of the present invention may provide wireless power converter  120  having one or more driving circuits for providing wireless power and a rectifier for receiving wireless power. These and other embodiments of the present invention may simplify the circuitry of the battery charger by using the output driver transistors of the power transmitting circuit as the rectifier in the power receiving circuit. An example is shown in the following figure. 
       FIG. 5  illustrates an example of a wireless power converter according to an embodiment of the present invention. In this example, power may be received or provided on node POWER SOURCE  2  by closing switch S 6 , which may include transistor M 21 . Resistor R 1  may be a series resistor used in monitoring current flow in this wireless power converter. 
     This circuitry may either provide or receive wireless power. This circuitry may provide power in a balanced or unbalanced mode of operation. In the balance mode of operation, output driver transistors M 5 -M 8  may be driven by signals V 5 -V 8  at their gates. Signals V 5 -V 8  may be non-overlapping pulse-width modulated signals that may generate an alternating current in power transfer coil L 3 . Power transfer coil L 3  may be AC coupled to output driver transistors M 5 -M 8  via capacitor C 1  and C 2 . In the unbalanced mode of operation, either pair of output driver transistors, M 5  and M 6 , or M 7  and M 8 , may be driven while the other pair may form a path to ground. For example, output drive transistors M 5  and M 6  may be driven by signals V 5  and V 6 , which may be non-overlapping pulse-width modulated signals. Transistor M 8  may be on to form a path to ground, while transistor M 7  may be off. The output of output driver transistors M 5  and M 6  may drive power transfer coil L 3  via capacitor C 1 . 
     While receiving wireless power, output driver transistors M 5 -M 8  may be off and the gate signals V 5 -V 8  may be low. The body diodes of transistors M 5 -M 8  may form a diode rectifier that may receive a current induced in the power transfer coil L 3  and generate a voltage VWD. Alternatively, transistors M 5 -M 8  may operate as a synchronous rectifier. The gate signals V 5 -V 8  may be based on currents sensed in transistors M 5 -M 8  such that transistors M 5 -M 8  operate in a reverse current conducting mode. Using transistors M 5 -M 8  as a synchronous rectifier may eliminate the forward diode drop loss that may be incurred using the body diodes of transistors M 5 -M 8  as a diode rectifier. In either mode, power may then be selectively coupled to line POWER SOURCE  2  through switch S 6 . 
       FIG. 6  illustrates an example of a wireless power converter for an accessory according to an embodiment of the present invention. This circuitry may either provide or receive wireless power. This circuitry may provide power in a balanced or unbalanced mode of operation. In the balance mode of operation, output driver transistors M 9 -M 12  may be driven by signals V 9 -V 12  at their gates. Signals V 9 -V 12  may be non-overlapping pulse-width modulated signals that may generate an alternating current in power transfer coil L 4 . Power transfer coil L 4  may be AC coupled to output driver transistors M 9 -M 12  via capacitor C 3  and C 4 . In the unbalanced mode of operation, either pair of output driver transistors, M 9  and M 10 , or M 11  and M 12 , may be driven while the other pair may form a path to ground. For example, output driver transistors M 9  and M 10  may be driven by signals V 9  and V 10 , which may be non-overlapping pulse-width modulated signals. Transistor M 12  may be on to form a path to ground, while transistor M 11  may be off. The output of output driver transistors M 9  and M 10  may drive power transfer coil L 4  via capacitor C 3 . 
     In these and other embodiments of the present invention, the currents in wireless power transfer coils L 3  and L 4  may alternate at a frequency of 100-200 kHz, though other frequencies, such as 6.78 MHz, may be used. 
     While receiving wireless power, driver transistors M 9 -M 12  may be off and the gate signals V 9 -V 12  may be low. The body diodes of transistors M 9 -M 12  may form a rectifier that may receive a current induced in power transfer coil L 4  and generate a voltage VWA. Alternatively, transistors M 9 -M 12  may operate as a synchronous rectifier. The gate signals V 9 -V 12  may be based on currents sensed in transistors M 9 -M 12  such that transistors M 9 -M 12  operate in a reverse current conducting mode. Using transistors M 9 -M 12  as a synchronous rectifier may eliminate the forward diode drop loss that may be incurred using the body diodes of transistors M 9 -M 12  as a diode rectifier. In either mode, the resulting voltage may then be used to power some or all of the remainder of accessory  160 . 
       FIG. 7  is a simplified example of a power transfer system of an electronic device and an accessory according to an embodiment of the present invention. In this figure, each of the switches are shown as being open to clarify their positions. Some of the bypass and the coupling capacitors shown in the above figures are omitted for clarity and simplicity. The switches in this and the following figures are simplified for clarity as well. 
     The circuitry provided by embodiments of the present invention may be highly flexible and may allow devices in an electronic system to transfer power in various ways. Examples are shown in the following figures. These examples are shown for illustrative purposes only and do not limit either the possible examples, the claims, or the possible embodiments of the present invention. 
     In a first example, power may be received from a connector in an electronic device and used to charge a battery in the electronic device and to further provide power to an accessory. Specifically, power may be received at a connector of the electronic device from a host or other electronic device or charger. This power may be received by a buck or other power converter in the battery charger. Some of this power may be provided to the battery and system (the circuitry in the electronic device), while the remainder may be provided to a boost converter in the battery charger, which may then provide power to the wireless power converter. One or more drivers in the wireless power converter may generate an alternating current through a first wireless power transmission coil. This wireless power may be received by a second wireless power transmission coil in an accessory. A rectifier across the wireless power transmission coil in the accessory may receive the wireless power and provide power to the accessory. 
       FIG. 8  is a flow chart showing the first example of power transfer according to an embodiment of the present invention. In act  810 , power may be received at a connector of an electronic device. This power may be received by a buck converter of the battery charger in act  820 . The output power may be used to charge a battery in the electronic device in act  830 . Power from the battery may be received by a boost converter in the battery charger, which may provide power to a wireless power converter in the electronic device in act  840 . In act  850 , wireless power may be provided to an accessory using the wireless power converter. The accessory may be powered by the received power in act  860 . 
       FIG. 9  is a simplified schematic of a power transfer system configured for the first example according to an embodiment of the present invention. Again in these examples, the decoupling and bypass capacitors have been omitted and switches have been simplified for clarity. In this configuration, power may be received at POWER SOURCE  1 , which may be connected to a pin or contact of a connector  112  or other wired connection of electronic device  100  as shown in  FIG. 1 . Connector  112  may be a USB Type-C, USB Type-A, lightning, or other type of connector. Power at connector  112  may be received from a host device, charger, or other electronic device. In these and other embodiments of the present invention, the voltage on POWER SOURCE  1  may instead be received from a wireless power converter or other wireless power source. In this particular example, the voltage on POWER SOURCE  1  may be relatively low, for example 5 V. Accordingly, this power may be boosted by a power converter (not shown), which may provide power to buck converter transistors M 1  and M 2  via switch S 1 . Signals V 1  and V 2  at the gates of transistors M 1  and M 2  may be non-overlapping pulse-width modulated signals to generate currents in inductor L 2 , though transistor M 2  may be off. The output voltage VOUT may be used to power system  130  as shown in  FIG. 1 . The output voltage VOUT may also be provided through a boost converter comprising inductor L 1  and transistors M 13  and M 4  in battery charger  110 . Signals V 4  and V 13  at the gates of transistors M 4  and M 13  may be non-overlapping pulse-width modulated signals to generate currents in inductor L 1 , though transistor M 13  may be off. Transistor M 3  may also be off, though M 3  may be configured to operate the same as M 13  and switch S 3  may be closed. The boost converter may provide power through switch S 5  to node POWER SOURCE  2 . POWER SOURCE  2  may power wireless power converter  120 , though in these and other embodiments of the present invention, POWER SOURCE  2  may instead provide power to a connector, such as a USB Type-C, USB Type-A, lightning, or other wired connection. The output driver transistors M 5 -M 8  in wireless power converter  120  may operate in a balanced or unbalance mode. In a balanced mode, output driver transistors M 5 -M 8  may be driven by gate signals V 5 -V 8 , which may be non-overlapping pulse-width modulated signals. These signals may generate an opening current in power transfer coil L 3 , which may be capacitively coupled through capacitors C 1  and C 2  to the output driver transistors M 5 -M 8 . In the unbalanced mode of operation, either pair of output driver transistors, M 5  and M 6 , or M 7  and M 8 , may be driven while the other pair may form a path to ground. For example, output drive transistors M 5  and M 6  may be driven by signals V 5  and V 6 , which may be non-overlapping pulse-width modulated signals. Transistor M 8  may be on to form a path to ground, while transistor M 7  may be off. The output of output driver transistors M 5  and M 6  may drive power transfer coil L 3  via capacitor C 1 . 
     The current in power transfer coil L 3  may induce a current in power transfer coil L 4  in accessory  160 . A resulting voltage may be capacitively coupled through capacitor C 3  and C 4  to transistors M 9 -M 12 . In this case, transistors M 9 -M 12  may act as a rectifier to generate voltage VWA across capacitor C 5 . The voltage VWA may then be used to power circuitry in accessory  160 . 
     Again, battery charger  110  and wireless power converter may include current limit and current regulation circuitry. For example, current in switch S 1  may be monitored, and if it is excessive, switch S 1  may be opened, thereby disconnecting POWER SOURCE  1  from battery charger  110 . Similarly, current in the switch S 6  may be monitored, and if excessive, switch S 6  may be opened. The same may be true of switches S 4  and S 5 . In this example, switches S 1 , S 5 , and S 6  may be closed, while switches S 2  and S 3  may be open. Switch S 4  may be closed to charge battery  150 . 
     Again in this example, power from battery charger  110  may be provided to battery  150  as well as to wireless power converter  120 . Accordingly, regulation circuitry may be included to ensure that wireless power converter  120  has sufficient power to operate properly. For example, any or all of the power converters may have configurable impedances that may be adjusted by varying the duty cycles of their gate signals such that wireless power converter  120  receives sufficient current to operate. 
     In a second example, wireless power may be received by an electronic device from an accessory and used to charge a battery in the electronic device. Specifically, power may be provided by one or more drivers in an accessory, which may generate an alternating current through a first wireless power transmission coil. This wireless power may be received by a second wireless power transmission coil in the electronic device. A rectifier in the wireless power converter may receive the wireless power and provide power to a buck converter in the battery charger. The buck converter may provide power to the battery and the system. 
       FIG. 10  is a flow chart showing the second example of power transfer according to an embodiment of the present invention. In act  1010 , wireless power may be generated by an accessory. This power may be received by a wireless power converter in an electronic device in act  1020 . Power from the wireless power converter may be received by a buck converter in a battery charger and used to charge a battery in act  1030 . Current may also be provided to the system in the electronic device. 
       FIG. 11  is a simplified schematic of a power transfer system configured for the second example according to an embodiment of the present invention. In this example, a voltage VWA may be generated in accessory  160 . Transistors M 9 -M 12  may operate in a balanced or unbalanced mode. In the balanced mode, transistors M 9 -M 12  may be driven by non-overlapping pulse-width modulated signals V 9 -V 12  to generate an alternating current in power transfer coil L 4 . In the unbalanced mode of operation, either pair of output driver transistors, M 9  and M 10 , or M 11  and M 12 , may be driven while the other pair may form a path to ground. For example, output driver transistors M 9  and M 10  may be driven by signals V 9  and V 10 , which may be non-overlapping pulse-width modulated signals. Transistor M 12  may be on to form a path to ground, while transistor M 11  may be off. The output of driver transistors M 9  and M 10  may drive power transfer coil L 4  via capacitor C 3 . The alternating current in power transfer coil L 4  may induce a current in power transfer coil L 3 , which may be coupled to transistors M 5 -M 8 . Transistors M 5 -M 8  may form a rectifier, which may generate a voltage VWD. The voltage VWD may be applied through closed switches S 5  and S 6  to node POWER SOURCE  2 , which may provide power to a buck converter comprising M 13 , M 4 , and inductor L 1 . In these and other embodiments of the present invention, node POWER SOURCE  2  may receive power from a connector, such as a USB Type-C, USB Type-A, lightning, or other wired connection. Signals V 4  and V 13  at the gates of transistors M 4  and M 13  may be non-overlapping pulse-width modulated signals to generate currents in inductor L 1 , though transistor M 4  may be off. Transistor M 3  may also be off, though M 3  may be configured to operate the same as M 13  and switch S 3  may be closed. The output of this converter may provide charge for battery  150  and power for system  130 , as shown in  FIG. 1 . In this example, switches S 2  and S 3  may also close, thereby providing power to the buck converter of M 1 , M 2 , and inductor L 2 . This additional converter may then also to charge battery  150  and provide power to system  130 , as shown in  FIG. 1 . This may provide an additional charging path when the received wireless power is at a high wattage. 
     In this example, current limiting circuitry may protect battery  150  from excessive charge. For example, current may be monitored and any or all of switches S 4 , S 5 , and S 6 , and any or all of these switches may be opened if excess current is detected. In this example, switches S 5  and S 6  may be closed, while switches S 1 , S 2 , and S 3  may be open. Switch S 4  may be closed to charge battery  150 . 
     In a third example, power may be received from a host or other electronic device or charger, and used to charge a battery and provide power to the system in an electronic device. Specifically, power may be received at a connector of the electronic device from a host or other electronic device or charger. This power may be received by a buck or other power converter in the battery charger. More specifically, in these and other embodiments of the present invention, the battery charger may include a two-phase buck or other type of converter, and this buck or other converter may convert the received power and provide it to the battery and system for a fast charging. 
       FIG. 12  is a flow chart showing the third example of power transfer according to an embodiment of the present invention. In act  1210 , power may be received at a connector of an electronic device. This power may be received with a first stage of the battery charger in act  1220 . The power received at the connector may also be provided to a second stage of the battery charger in act  1230 . In act  1240 , a battery in the electronic device may be charged using the first and second stages of the wireless power converter. The first and second stages may be buck converters or other types of power converters. 
       FIG. 13  is a simplified schematic of a power transfer system configured for the third example according to an embodiment of the present invention. In this example, switches S 1  and S 2  may both be closed providing voltage on POWER SOURCE  1  from connector  112  or other wired connection of electronic device  100  to driver transistors M 1 -M 4 , which may form first and second buck converters. Connector  112  may be a USB Type-C, USB Type-A, lightning, or other type of connector. In these and other embodiments of the present invention, POWER SOURCE  1  may instead be received from a wireless power converter or other wireless power source. Transistors M 1 -M 4  may be driven by non-overlapping pulse-width modulated signals V 1 -V 4 , though transistors M 2  and M 4  may be off and transistor M 13  may be connected to operate in parallel with transistor M 3 . The drivers may provide currents through inductors L 1  and L 2  to generate VOUT, which may be used to power system  130 , as shown in  FIG. 1 . Switch S 4  may also close thereby allowing the driver transistors M 1 -M 4  to charge battery  150 . In this example, two buck converters may be used to charge battery  150  and provide power to system  130  for fast charging. In such a situation, power received at wireless power converter  120  may be ignored by electronic device  100 . This configuration may be particularly useful where a high voltage, such as 9 or 15 volts, is received at connector  112  of electronic device  100 , as shown in  FIG. 1 . 
     In this example, current limiting circuitry may protect battery  150  from excessive charge. For example, current may be monitored and any or all of switches S 1 , S 2 , and S 4 , and any or all of these switches may be opened if excess current is detected. In this example, switches S 1  and S 2  may be closed, while switches S 3 , S 5 , and S 6  may be open. Switch S 4  may be closed to charge battery  150 . 
     In a fourth example, power may be provide by a battery of an electronic device and used to provide wireless power to an accessory. Specifically, power may be received from the battery by a boost or other converter in the battery charger. The boost converter may provide power to a wireless power converter. One or more drivers in the wireless power converter may generate an alternating current through a first wireless power transmission coil. This wireless power may be received by a second wireless power transmission coil in an accessory. A rectifier across the wireless power transmission coil in the accessory may receive the wireless power and provide power to the accessory. 
       FIG. 14  is a flow chart showing the fourth example of power transfer according to an embodiment of the present invention. In this example, power may be provided from a battery to a boost or other converter in a battery charger. Power may be provided from the boost converter to a wireless power converter in act  1410 . The wireless power may be provided from the wireless power converter to an accessory in act  1420 . The accessory may be powered the received wireless power in act  1430 . 
       FIG. 15  is a simplified schematic of a power transfer system configured for the fourth example according to an embodiment of the present invention. In this example, switch S 4  may be closed, thereby providing power from battery  150  to a boost converter comprising transistors M 13  and M 4 , along with inductor L 1  Signals V 4  and V 13  at the gates of transistors M 4  and M 13  may be non-overlapping pulse-width modulated signals to generate currents in inductor L 1 , though transistor M 13  may be off. Transistor M 3  may also be off, though M 3  may be configured to operate the same as M 13  and switch S 3  may be closed. Power from the boost converter may be provided to wireless power converter  120  via closed switch S 5  and node POWER SOURCE  2 , though in other embodiments of the present invention, this power may be provided to a connector, such as a USB Type-C, USB Type-A, lightning, or other wired connection. As before, transistors M 5 -M 8  may operate in a balanced or unbalanced mode. In a balanced mode, transistors M 5 -M 8  may be driven by non-overlapping pulse-width modulated signals V 5 -V 8  to generate an alternating current in power transfer coil L 3 . In the unbalanced mode of operation, either pair of output driver transistors, M 5  and M 6 , or M 7  and M 8 , may be driven while the other pair may form a path to ground. For example, output drive transistors M 5  and M 6  may be driven by signals V 5  and V 6 , which may be non-overlapping pulse-width modulated signals. Transistor M 8  may be on to form a path to ground, while transistor M 7  may be off. The output of output driver transistors M 5  and M 6  may drive power transfer coil L 3  via capacitor C 1 . The alternating current in power transfer coil L 3  may induce a current in power transfer coil L 4  in accessory  160 . Transistors M 9 -M 12  may be off, and this induced current may generate voltage VWA across the rectifier formed by transistors M 9 -M 12 . The resulting voltage VWA may be used to power accessory  160 . In this example, switches S 1 , S 2 , and S 3  may also close, thereby providing power from the battery to the boost converter of M 1 , M 2 , and inductor L 2 . This additional power converter may then also provide power from battery  150  to wireless power converter  120 . This may provide an additional charging path when the received wireless power is at a high wattage. 
     In this example, current limiting circuitry may protect battery  150  from excessive charge. For example, current may be monitored in any of all of switches S 4 , S 6 , and S 5 , and any or all of these switches may be opened if excess current is detected. In this example, switches S 5  and S 6  may be closed, while switches S 1 , S 2 , and S 3  may be open. Switch S 4  may be closed to charge battery  150 . 
     In a fifth example, power received at a connector of an electronic device may be used to provide power to a battery and system of the electronic device. Power may also be provided wirelessly from the electronic device to an accessory. Specifically, power may be received at a connector of the electronic device from a host or other electronic device or charger. This power may be provided to a two-phase buck or other power converter in the battery charger. The output power from the buck converter may be provided to the battery and system. Power from the connector may also be provided to a wireless power converter. This power may be provided to the wireless power converter through a bypass path that connects the connector of the electronic device to the wireless power converter. One or more drivers in the wireless power converter may generate an alternating current through a first wireless power transmission coil. This wireless power may be received by a second wireless power transmission coil in an accessory. A rectifier across the coil may receive the wireless power and provide power to the accessory. 
       FIG. 16  is a flow chart showing the fifth example of power transfer according to an embodiment of the present invention. Power may be received from a connector of the electronic device in act  1610 . This power may be received by a two-phase buck converter in the battery charger, the output of which may be provided to a battery in act  1620 . Power from the connector may also be provided using a bypass path to the wireless power converter in act  1630 . Power generated by the wireless power converter may be provided to an accessory in act  1640 . Power received by the accessory may be used to power the accessory in act  1650 . 
       FIG. 17  is a simplified schematic of a power transfer system configured for the fifth example according to an embodiment of the present invention. In this example, power may be received from a connector  112  or other wired connection of electronic device  100 , though power may instead be received from a wireless power converter or other wireless source in these and other embodiments of the present invention. Connector  112  may be a USB Type-C, USB Type-A, lightning, or other type of connector. Specifically, the voltage on POWER SOURCE  1  may be a high voltage, for example 9 or 15 volts. Switches S 1  and S 2  may close, thereby providing power on POWER SOURCE  1  to a two-phase buck converter comprising transistors M 1 , M 2 , M 13 , and M 4 , and inductors L 1  and L 2 . Signals V 1 -V 4  at the gates of transistors M 1 -M 4  may be non-overlapping pulse-width modulated signals to generate currents in inductors L 1  and L 2 , though transistors M 2  and M 4  may be off. Transistor M 13  may also be off, though M 13  may be configured to operate the same as M 3  and switch S 5  may be closed. Using an additional power converter stage may provide an extra 5 watts of power to charge the battery, though this may vary depending on exact circuit implementation. Switches S 2 , S 3 , and S 6  may be closed, thereby providing the voltage on POWER SOURCE  1  to POWER SOURCE  2  and VWD. The voltage VWD may be used to power driver transistors M 5 -M 8  in wireless power converter  120 , though in these and other embodiments of the present invention VWD may instead provide power to a connector, such as a USB Type-C, USB Type-A, lightning, or other wired connection. Wireless power converter  120  may operate in a balanced or unbalanced mode. In the balanced mode of operation, transistors M 5 -M 8  may be driven by non-overlapping pulse-width modulated signals V 5 -V 8  to generate an alternating current in power transfer coil L 3 . In the unbalanced mode of operation, either pair of output driver transistors, M 5  and M 6 , or M 7  and M 8 , may be driven while the other pair may form a path to ground. For example, output drive transistors M 5  and M 6  may be driven by signals V 5  and V 6 , which may be non-overlapping pulse-width modulated signals. Transistor M 8  may be on to form a path to ground, while transistor M 7  may be off. The output of output driver transistors M 5  and M 6  may drive power transfer coil L 3  via capacitor C 1 . The alternating current in power transfer coil L 3  may induce an alternating current in power transfer coil L 4  in accessory  160 , which may be rectified by a rectifier formed of transistors M 9 -M 12  in accessory  160  to generate voltage VWA. The voltage VWA may be used to power accessory  160 . 
     Again, additional current limitation circuitry may be included. For example, a current in any or all of switches S 1 , S 2 , S 3 , S 4 , and S 6  may be monitored, and any of all of these switches may be opened in the event of excessive current. 
     Again, additional current regulation circuitry may also be included. For example, any or all of the power converters may include current monitoring circuitry. The impedances of any or all of the power converters may be adjusted by varying the duty cycles of their gate signals to ensure that wireless power converter  120  receives sufficient current to operate. In this example, switches S 1 , S 2 , S 3 , and S 6  may be closed, while switch S 5  may be open. Switch S 4  may be closed to allow charging of battery  150 . 
     In a sixth example, both wired and wireless power may be received by an electronic device and used to charge a battery and provide power to the system of the electronic device. Specifically, power may be received at a connector of the electronic device from a host or other electronic device or charger. This power may be received by a buck or other power converter in the battery charger. The output power of the buck converter may be provided to the battery and system. At the same time, power may be provided by one or more drivers in an accessory, which may generate an alternating current through a first wireless power transmission coil. This wireless power may be received by a second wireless power transmission coil in the electronic device. A rectifier in the wireless power converter may receive the wireless power and provide power a second buck converter, which may also provide power to the battery and the system. This combined current from wired and wireless sources may speed the rate of charging of the battery. 
       FIG. 18  is a flow chart showing the sixth example of power transfer according to an embodiment of the present invention. In act  1810 , power may be received at a connector of an electronic device. This power may be received by a buck converter in the battery charger in act  1820 . The battery may be charged with the output of the buck converter in act  1830 . At the same time, wireless power may be generated by an accessory in act  1840 . This wireless power may be received from an accessory by a wireless power converter in the electronic device in act  1850 . Power from the wireless power converter may be received by a buck converter and the battery may be charged with its output in act  1860 . 
       FIG. 19  is a simplified schematic of a power transfer system configured for the sixth example according to an embodiment of the present invention. In this configuration, power may be received at POWER SOURCE  1 , which may be connected to a pin or contact of a connector  112  or other wired connection of electronic device  100 . Connector  112  may be a USB Type-C, USB Type-A, lightning, or other type of connector. Power at the connector may be from a host device, charger, or other electronic device. In these and other embodiments of the present invention, POWER SOURCE  1  may instead be received from a wireless power converter or other wireless power source. POWER SOURCE  1  may be provided to transistors M 1  and M 2 , which may be power converter transistors of a buck or other type of power converter. Signals V 1  and V 2  at the gates of transistors M 1  and M 2  may be non-overlapping pulse-width modulated signals (though M 2  may be off) to generate currents in inductor L 2 . The output voltage VOUT may be used to charge battery  150  and power system  130  as shown in  FIG. 1 . At the same time, a voltage VWA may be generated in accessory  160 . Transistors M 9 -M 12  may operate in a balanced or unbalanced mode of operation. In the balanced mode, transistors M 9 -M 12  may be driven by non-overlapping pulse-width modulated signals V 9 -V 12  to generate an alternating current in power transfer coil L 4  via capacitors C 3  and C 4 . In the unbalanced mode of operation, either pair of output driver transistors, M 9  and M 10 , or M 11  and M 12 , may be driven while the other pair may form a path to ground. For example, output driver transistors M 9  and M 10  may be driven by signals V 9  and V 10 , which may be non-overlapping pulse-width modulated signals. Transistor M 12  may be on to form a path to ground, while transistor M 11  may be off. The output of output driver transistors M 9  and M 10  may drive power transfer coil L 4  via capacitor C 3 . The alternating current in power transfer coil L 4  may induce a current in power transfer coil L 3 , which may be coupled to transistors M 5 -M 8 . Transistors M 5 -M 8  may form a rectifier, which may generate a voltage VWD, which may be provided to node POWER SOURCE  2 . In these and other embodiments of the present invention, POWER SOURCE  2  may instead receive power from a connector, such as a USB Type-C, USB Type-A, lightning, or other wired source. The voltage VWD may be applied through closed switches S 6  and S 3  to power the buck converter comprising transistors M 13  and M 4 , and inductor L 1 . Signals V 4  and V 13  at the gates of transistors M 4  and M 13  may be non-overlapping pulse-width modulated signals to generate currents in inductor L 1 , though transistor M 4  may be off. Transistor M 3  may also be off (though M 3  may be configured to operate the same as M 13  and switch S 3  may be closed.) The output of this second buck converter may provide charge for battery  150  and power for system  130 , as shown in  FIG. 1 . 
     In this example, current limiting circuitry may protect battery  150  from excessive charge. For example, current may be monitored and any or all of switches S 1 , S 4 , S 5 , and S 6 , and any or of these switches may be opened if excess current is detected. In this example, switches S 1 , S 5 , and S 6  may be closed, while switches S 2  and S 3  may be open. Switch S 4  may be closed to allow battery  150  to be charged. 
     In a seventh example, wireless power may be received from an accessory and wired power may be provided over a connector of an electronic device. Specifically, power may be provided by one or more drivers in a first accessory, which may generate an alternating current through a first wireless power transmission coil. This wireless power may be received by a second wireless power transmission coil in the electronic device. A rectifier in the wireless power converter may receive the wireless power and provide this power to a buck converter in a battery charger. The output of the buck converter may be used to charge a battery and to provide power to system. Power may also be received from the battery and provided to a boost converter in the battery charger. The output of the boost converter may provide power to a connector of the electronic device. Power may then be received from the connector by a second accessory. 
       FIG. 20  is a flow chart showing the seventh example of power transfer according to an embodiment of the present invention. Wireless power may be provided by a first accessory in act  2010 . The wireless power may be received with a wireless power converter in an electronic device in act  2020 . This power may in turn be received by a buck converter in a battery charger. A battery in the electronic device may be charged with the output power of the buck converter in act  2030 . The power from the battery may be provided to a boost converter in the battery charger, which may provide power to a connector of the electronic device in act  2040 , where it may be received by a second accessory or host or other electronic device. 
       FIG. 21  is a simplified schematic of a power transfer system configured for the seventh example according to an embodiment of the present invention. A voltage VWA may be generated in accessory  160 . Transistors M 9 -M 12  may operate in a balanced or unbalanced mode. In the balanced mode, transistors M 9 -M 12  may be driven by non-overlapping pulse-width modulated signals V 9 -V 12  to generate an alternating current in power transfer coil L 4  via capacitors C 3  and C 4 . In the unbalanced mode of operation, either pair of output driver transistors, M 9  and M 10 , or M 11  and M 12 , may be driven while the other pair may form a path to ground. For example, output driver transistors M 9  and M 10  may be driven by signals V 9  and V 10 , which may be non-overlapping pulse-width modulated signals. Transistor M 12  may be on to form a path to ground, while transistor M 11  may be off. The output of output driver transistors M 9  and M 10  may drive power transfer coil L 4  via capacitor C 3 . The alternating current in power transfer coil L 4  may induce a current in power transfer coil L 3 , which may be coupled to transistors M 5 -M 8  in wireless power converter  120  of electronic device  100 . Transistors M 5 -M 8  may form a rectifier, which may generate a voltage VWD. The voltage VWD may be coupled to POWER SOURCE  2  via closed switch S 6 . In these and other embodiments of the present invention, POWER SOURCE  2  may instead receive power from a connector, such as a USB Type-C, USB Type-A, lightning, or other wired connection. POWER SOURCE  2  may be applied through dosed switch S 5  to a buck converter comprising transistors M 13  and M 4 , as well as inductor L 1 , the output of which may provide charge for battery  150  and power for system  130 , as shown in  FIG. 1 . Signals V 4  and V 13  at the gates of transistors M 4  and M 13  may be non-overlapping pulse-width modulated signals to generate currents in inductor L 1 , though transistor M 4  may be off. Transistor M 3  may also be off, though M 3  may be configured to operate the same as M 13  and switch S 3  may be closed. Power from the battery may be provided through switch S 4  to a boost converter including transistors M 1  and M 2 , and inductor L 2 . Signals V 1  and V 2  at the gates of transistors M 1  and M 2  may be non-overlapping pulse-width modulated signals to generate currents in inductor L 1 , though transistor M 1  may be off. This boost converter may provide power to POWER SOURCE  1 , which may be connected to a pin or contact of connector  112  or other wired connection of electronic device  100 . Connector  112  may be a USB Type-C, USB Type-A, lightning, or other type of connector. Power may be received from connector  112  by a second accessory or host or other electronic device, though in these and other embodiments of the present invention, power may instead be provided to a wireless power converter or other wireless power receiver. Also in this example, power may be routed using the bypass path of S 2  and S 3 , thereby providing power from wireless power converter  120  to connector  112  or wireless power converter  120 . 
     Again, additional current limitation circuitry may be included. For example, a current in any or all of switches S 1 , S 4 , S 5 , and S 6  may be monitored, and any or all of these switches may be opened in the event of excessive current. 
     Again, additional current regulation circuitry may also be included. For example, any or all of the power converters may include current monitoring circuitry. The impedances of any or all of these power converters may be adjusted by varying the duty cycles of their gate signals to ensure that wireless power converter  120  receives sufficient current to operate. In this example, switches S 1 , S 5 , and S 6  may be closed, while switches S 2  and S 3  may be open. Switch S 4  may be closed to allow charging of battery  150 . 
     These and other embodiments of the present invention may not support each and every one of the configurations disclosed herein. That is, these and other embodiments of the present invention may provide a subset of these features. Also, in these and other embodiments of the present invention, other power transfer configurations may be possible. For example, power may be provided from battery  150  to connector  112  through either or both battery charger  110  and bypass path  140 . Power may also be provided from battery  150  to both connector  112  and wireless power converter  120 . 
     Battery charger  110 , wireless power converter  120 , and bypass path  140  may be configured for these various operations in different ways. For example, one or more connector or orientation detection contacts may be used to determine when an external host or other electronic device or charger is connected to the battery charger via connector  112 . These connector or orientation detection contacts may be coupled to circuitry (not shown) that may be used to determine whether a connected device should provide power to one or more of system  130 , battery  150 , or wireless power converter  120 , or whether the connected device should receive power from one or more of these sources. Circuitry connected to wireless power converter  120  may determine when an external accessory or charger is inductively connected to wireless power converter  120 . This circuitry may further determine whether an inductively connected device should provide power to one or more of system  130 , battery  150 , or battery charger  110 , or whether the inductively connected device should receive power from one or more of these sources. Circuitry connected to bypass path  140  may determine whether a power supply received at connector  112  is sufficient to directly power wireless power converter  120  and may connect these circuits accordingly. This circuitry may also determine whether wireless power converter  120  may provide power to connector  112 , and may connect these circuits accordingly. 
     Embodiments of the present invention may provide charging circuitry that may be located in various types of devices, such as portable computing devices, tablet computers, desktop computers, laptops, all-in-one computers, wearable computing devices, cellular phones, smart phones, media phones, storage devices, portable media players, navigation systems, monitors, power supplies, adapters, remote control devices, chargers, and other devices. 
     The above description of embodiments of the invention has been presented for the purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise form described, and many modifications and variations are possible in light of the teaching above. The embodiments were chosen and described in order to best explain the principles of the invention and its practical applications to thereby enable others skilled in the art to best utilize the invention in various embodiments and with various modifications as are suited to the particular use contemplated. Thus, it will be appreciated that the invention is intended to cover all modifications and equivalents within the scope of the following claims.

Metadata:
Filing Date: 20180907
Publication Date: 20211123
Grant Date: 20211123
Priority Date: 20180507
Inventors: GU, BIN
HU, Yongxuan
TERRY, STEPHEN C.
ZHAO, DI
PARIKH, RUCHI J.
BLACK, MICHAEL D.
CHEN, WEIYUN
Assignee: APPLE INC
CPC Classifications: [{"code": "H02J7/342", "inventive": true, "first": true, "tree": "[]"}, {"code": "H02J50/12", "inventive": true, "first": false, "tree": "[]"}, {"code": "H02J2207/20", "inventive": false, "first": false, "tree": "[]"}, {"code": "H02M3/33576", "inventive": true, "first": false, "tree": "[]"}, {"code": "H02J2207/20", "inventive": false, "first": false, "tree": "[]"}, {"code": "H02J7/00", "inventive": true, "first": false, "tree": "[]"}, {"code": "H02M3/33584", "inventive": true, "first": false, "tree": "[]"}, {"code": "H02J50/10", "inventive": true, "first": false, "tree": "[]"}, {"code": "H02M3/158", "inventive": true, "first": false, "tree": "[]"}, {"code": "H02M3/33592", "inventive": true, "first": false, "tree": "[]"}, {"code": "H02J7/342", "inventive": true, "first": true, "tree": "[]"}, {"code": "H02J50/12", "inventive": true, "first": false, "tree": "[]"}, {"code": "H02J7/0045", "inventive": true, "first": false, "tree": "[]"}, {"code": "H02J50/10", "inventive": true, "first": false, "tree": "[]"}, {"code": "H02J7/0045", "inventive": true, "first": false, "tree": "[]"}, {"code": "H02J7/025", "inventive": true, "first": true, "tree": "[]"}, {"code": "H02J7/00", "inventive": true, "first": false, "tree": "[]"}]
Family ID: 68385541