Abstract: A battery case has first and second coils on opposing sides of a battery and has switching circuitry that is coupled between the first and second coils. The battery case has a battery that provides supplemental battery power wirelessly to a wireless power receiving device via the second coil when the switching circuitry is in an open state. The case can also receive power wirelessly with the first coil from a wireless charging mat when the switching circuitry is in the open state. In a closed state, the switching circuitry shorts the first and second coils together so that current flowing through the first coil flows through the second coil in series and so that wireless power from the wireless charging mat that is received with the first coil is transmitted wirelessly to the wireless power receiving device using the second coil.

Abstract: An electronic device may include a proximity sensor for detecting whether an external object is in the vicinity of the device. The proximity sensor may have a light detector and a light source that can be reused for data communications. The light detector may be coupled to optical receiver circuitry, whereas the light source may be coupled to optical transmitter circuitry. The optical transmitter circuitry may include encoding circuits configured to convert electrical signals to optical signals. The optical receiver circuitry may include decoding circuits configured to convert optical signals to electrical signals. The optical signals can be encoded and decoded using pulse width modulation schemes or amplitude modulation schemes.

Abstract: A battery case has first and second coils on opposing sides of a battery and has switching circuitry that is coupled between the first and second coils. The battery case has a battery that provides supplemental battery power wirelessly to a wireless power receiving device via the second coil when the switching circuitry is in an open state. The case can also receive power wirelessly with the first coil from a wireless charging mat when the switching circuitry is in the open state. In a closed state, the switching circuitry shorts the first and second coils together so that current flowing through the first coil flows through the second coil in series and so that wireless power from the wireless charging mat that is received with the first coil is transmitted wirelessly to the wireless power receiving device using the second coil.

Abstract: A battery case has first and second coils on opposing sides of a battery and has switching circuitry that is coupled between the first and second coils. The battery case has a battery that provides supplemental battery power wirelessly to a wireless power receiving device via the second coil when the switching circuitry is in an open state. The case can also receive power wirelessly with the first coil from a wireless charging mat when the switching circuitry is in the open state. In a closed state, the switching circuitry shorts the first and second coils together so that current flowing through the first coil flows through the second coil in series and so that wireless power from the wireless charging mat that is received with the first coil is transmitted wirelessly to the wireless power receiving device using the second coil.

Abstract: A battery case has first and second coils on opposing sides of a battery and has switching circuitry that is coupled between the first and second coils. The battery case has a battery that provides supplemental battery power wirelessly to a wireless power receiving device via the second coil when the switching circuitry is in an open state. The case can also receive power wirelessly with the first coil from a wireless charging mat when the switching circuitry is in the open state. In a closed state, the switching circuitry shorts the first and second coils together so that current flowing through the first coil flows through the second coil in series and so that wireless power from the wireless charging mat that is received with the first coil is transmitted wirelessly to the wireless power receiving device using the second coil.

Abstract: An electronic device has a battery system with control circuitry for use during charging and discharging. The battery pack has two battery cells coupled in series. The control circuitry includes battery charging circuitry that applies a charging current to the battery pack during charging. The control circuitry includes bleed resistors and switches that can be selectively activated to bleed charging current away from a selected cell during charging. This allows the control circuitry to balance charges stored on the cells and to balance associated cell voltages. The control circuitry is configured to maintain information on a difference between the charge stored on the first battery cell and the charge stored on the second battery cell. Information on this charge difference value is maintained during charging and discharging and is used in establishing a battery pack charging voltage target.

Abstract: Methods, structures, and apparatus that are able to transfer power through a device power contact while minimizing its corrosion. During a first period, a power supply may be connected to the device power contact. During a second, subsequent period the power supply may be disconnected from the device power contact and a quasi-resonant circuit connected to the device power contact may cause a voltage on the device power contact to ring. At the end of the second period, the voltage on the device power contact may be approximately equal to a voltage of the power supply. The power supply voltage may have a first polarity and the voltage on the device power contact may have a second polarity for a portion of the second period, the second polarity opposite the first polarity.

Abstract: A method and apparatus for a boost converter topology for low battery voltage support. In the method, an input voltage is boosted by closing first through third switches and then opening a fourth switch to charge a capacitor. The first and second switches are then opened. The voltage is then doubled by closing the third and fourth switches to discharge the first capacitor into a second capacitor and charging a third capacitor. A further embodiment provides an additional method for selectively boosting an input voltage to an electronic device. The method first characterizes the efficiency of a circuit, and then determines a crossover point for a ratio of output voltage to input voltage, and then enabling or disabling a voltage boost converter based on the crossover point.