Abstract: Inductive coil assemblies for wireless power transfer can be provided for an electronic device having a slot to receive an accessory and an accessory having an attachment region that is insertable into the slot. The inductive coil assembly of the device can extend along a sidewall of the slot. The inductive coil assembly of the accessory can extend along one side surface of the attachment region of the accessory. The opposite sidewall of the slot and side surface of the attachment region of the accessory can provide mechanical retention features.

Abstract: A device in a wireless power system may be operable with a removable accessory such as a case. The device may transmit or receive wireless power through the case while the electronic device is coupled to the case. The case may have a folio shape with a front cover portion that covers the display of the electronic device. The case may have an embedded ferrimagnetic core that relays magnetic flux during wireless power transfer operations. Magnetic alignment structures in the case may position the ferrimagnetic core in the case in a high magnetic flux density region between the power transmitting device and the power receiving device. The ferrimagnetic core relays the magnetic flux between a transmitting coil in the power transmitting device and a receiving coil in the power receiving device. The ferrimagnetic core may be formed in a front portion, a sidewall, or a rear wall of a case.

Abstract: A wireless power system has a wireless power transmitting device and multiple wireless power receiving devices. The wireless power transmitting device may have a foldable housing. The wireless power transmitting device has wireless power coils that are used in transmitting wireless power to electronic devices such as cellular telephones, wristwatches, ear buds battery cases, ear buds, computer styluses, and other electronic devices. A rectifier can be coupled to a wireless power coil. In a first mode the coil transmits wireless power to a cellular telephone or other device. In a second mode, the coil is used in receiving wireless power from the cellular telephone or other device. The received wireless power can be retransmitted to other devices.

Abstract: A personal electronic device (e.g., a tablet computer) may be configured to wirelessly charge an accessory (e.g., a stylus) through a display face of the device. At least a portion of the display face may be transparent to facilitate display viewing. A wireless charging assembly disposed within the enclosure may include a core having one or more windings disposed thereon, which may be configured to generate a magnetic flux above the display face to couple to the accessory. The core may be a pot core, a modified pot core, or may have another shape, such as a PQ core. The one or more windings may be disposed on one or more posts of a pot core, or additionally or alternatively, may be disposed on another portion of the core. A metallic shield may be disposed about the wireless charging assembly, thereby surrounding multiple sides of the wireless charging assembly.

Abstract: An electronic device can include a metallic or non-metallic housing having a window therethrough, a wireless power transfer coil disposed inside the housing adjacent the window, and a non-metallic cover disposed within the window that protects the wireless power transfer coil, the non-metallic cover incorporating at least one ferromagnetic region that improves magnetic coupling of the wireless power transfer coil to a corresponding wireless power transfer coil of another device by providing a high magnetic permeability flux path. The non-metallic cover and the at least one ferromagnetic region have surface finishes selected to visually match or coordinate with the housing.

Abstract: An electronic device in a wireless power system may be operable with a removable accessory such as a case. The device may have coplanar power transmitting and power receiving coils. The transmitting coil may be positioned within a central opening of the receiving coil. The removable accessory may have an embedded receiving coil configured to receive wireless power from the transmitting coil of the electronic device. The receiving coil of the electronic device may receive wireless power from a power transmitting device such as charging mat. The receiving coil of the electronic device may operate up to a higher maximum power than the transmitting coil of the electronic device. The power transmitting coil and power receiving coil in the electronic device may operate at different power transmission frequencies. To mitigate crosstalk, the power transmitting coil's operation frequency may be a non-integer multiple of the power receiving coil's operation frequency.

Abstract: A wireless power transfer system can include an electronic device including a first wireless power transfer coil and wireless power transfer circuitry coupled to the wireless power transfer coil. The wireless power transfer circuitry can be capable of receiving power and transmitting power wirelessly via the first wireless power transfer coil. The system can further include an accessory device including a second wireless power transfer coil, a rectifier coupled to the second wireless power transfer coil, and an energy storage device coupled to the rectifier by a regulator circuit. The wireless power transfer circuitry can operate in a pulsed or burst wireless power transfer mode to deliver power to the accessory device.

Abstract: An electronic device (that is capable of both transmitting and receiving wireless power) may be physically and inductively coupled to a removable accessory (that only receives wireless power). The electronic device and removable accessory may optionally be placed on a power transmitting device. In response to the electronic device and removable accessory being placed on a wireless power transmitting device, the electronic device may switch from a power transmitting mode (in which the electronic device transmits wireless power to the removable accessory) to a power receiving mode (in which the electronic device receives wireless power from the wireless power transmitting device). To ensure the electronic device detects the wireless power transmitting device and switches to the power receiving mode in this scenario, the electronic device may transmit wireless power in bursts separated by sleep periods while in the power transmitting mode.

Abstract: An inductor includes a plurality of stacked core parts having aligned central openings, at least one spacer separating the core parts from one another, and a winding comprising a plurality turns wound around the stack of core parts through central openings of the core parts. The at least one spacer may include respective groups of spacers disposed between respective pairs of the core parts. In some embodiments, the at least one spacer may include a plurality of spacers disposed between first and second ones of the core parts and radially distributed in a circular pattern aligned with the first and second core parts.

Abstract: The disclosure is directed to wireless power systems that include a ferromagnetic core formed of nanocrystalline material disposed on a ferrite. The wireless power systems can have reduced saturation and/or lossiness.

Abstract: A personal electronic device (e.g., a tablet computer) may be configured to wirelessly charge an accessory (e.g., a stylus) through a display face of the device. At least a portion of the display face may be transparent to facilitate display viewing. A wireless charging assembly disposed within the enclosure may include a core having one or more windings disposed thereon, which may be configured to generate a magnetic flux above the display face to couple to the accessory. The core may be a pot core, a modified pot core, or may have another shape, such as a PQ core. The one or more windings may be disposed on one or more posts of a pot core, or additionally or alternatively, may be disposed on another portion of the core. A metallic shield may be disposed about the wireless charging assembly, thereby surrounding multiple sides of the wireless charging assembly.

Abstract: An electronic device in a wireless power system may be operable with a removable accessory such as a case. The device may convey wireless power to, from, or through the case while the device is coupled to the case. The device may have coplanar power transmitting and power receiving coils. The removable accessory may have an embedded switchable ferrimagnetic core and a coil that overlaps the switchable ferrimagnetic core. The switchable ferrimagnetic core may be operable in a first state where the switchable ferrimagnetic core is unsaturated. The switchable ferrimagnetic core may be operable in a second state where the switchable ferrimagnetic core is saturated by a magnetic field from a permanent magnet in a wireless power transmitting device. In the second state, the switchable ferrimagnetic core may have a lower magnetic permeability and higher magnetic reluctance than in the first state.

Abstract: An electronic device in a wireless power system may be operable with a removable accessory such as a case. The device may have coplanar power transmitting and power receiving coils. The transmitting coil may be positioned within a central opening of the receiving coil. The removable accessory may have an embedded receiving coil configured to receive wireless power from the transmitting coil of the electronic device. The receiving coil of the electronic device may receive wireless power from a power transmitting device such as charging mat. The receiving coil of the electronic device may operate up to a higher maximum power than the transmitting coil of the electronic device. The power transmitting coil and power receiving coil in the electronic device may operate at different power transmission frequencies. To mitigate crosstalk, the power transmitting coil's operation frequency may be a non-integer multiple of the power receiving coil's operation frequency.

Abstract: A device in a wireless power system may be operable with a removable accessory such as a case. The device may transmit or receive wireless power through the case while the electronic device is coupled to the case. The case may have a folio shape with a front cover portion that covers the display of the electronic device. The case may have an embedded ferrimagnetic core that relays magnetic flux during wireless power transfer operations. Magnetic alignment structures in the case may position the ferrimagnetic core in the case in a high magnetic flux density region between the power transmitting device and the power receiving device. The ferrimagnetic core relays the magnetic flux between a transmitting coil in the power transmitting device and a receiving coil in the power receiving device. The ferrimagnetic core may be formed in a front portion, a sidewall, or a rear wall of a case.

Abstract: A wireless power system has a wireless power transmitting device and multiple wireless power receiving devices. The wireless power transmitting device may have a foldable housing. The wireless power transmitting device has wireless power coils that are used in transmitting wireless power to electronic devices such as cellular telephones, wristwatches, ear buds battery cases, ear buds, computer styluses, and other electronic devices. A rectifier can be coupled to a wireless power coil. In a first mode the coil transmits wireless power to a cellular telephone or other device. In a second mode, the coil is used in receiving wireless power from the cellular telephone or other device. The received wireless power can be retransmitted to other devices.

Abstract: An apparatus includes a first coil, a second coil having a first side facing a first side of the first coil, a first radial array of magnetic material bodies disposed on a second side of the first coil, and a second radial array of magnetic material bodies disposed on a second side of the second coil such that respective magnetic material bodies of the second radial array overlap respective magnetic material bodies of the first radial array. The apparatus may be included in a wireless power transfer system.

Abstract: An inductor includes a plurality of stacked core parts having aligned central openings, at least one spacer separating the core parts from one another, and a winding comprising a plurality turns wound around the stack of core parts through central openings of the core parts. The at least one spacer may include respective groups of spacers disposed between respective pairs of the core parts. In some embodiments, the at least one spacer may include a plurality of spacers disposed between first and second ones of the core parts and radially distributed in a circular pattern aligned with the first and second core parts.