Abstract: A driver circuit provides power from a power source to a load. The driver circuit includes a surge protector, an input stage (e.g., full wave rectifier), a controller, an overvoltage protection circuit, and an output stage (e.g., a half bridge inverter). The input stage receives power from the power source and provides a direct current (DC) power rail. The controller operates the output stage to provide power from the DC power rail to the load. The overvoltage protection circuit shuts down the controller when the DC power rail exceeds a predetermined voltage. This ceases operation of the output stage, protecting the output stage from damage while the DC power rail is above the predetermined voltage.

Abstract: A power converter can be implemented with a boosted-output inverter, which integrates the functionality of a voltage converter (e.g., boost converter) and a voltage inverter. In particular, a boosted-output inverter includes a primary tank inductor coupled in series with a secondary tank inductor at a central node. The boosted-output inverter also includes two voltage-controlled switches that respectively define a charging phase and a discharging phase of the primary tank inductor. While the primary tank inductor is charging, the secondary tank inductor is inverted to ground. In this manner, current though the secondary tank inductor alternates at a voltage boosted by the fly-back voltage of the primary tank inductor exhibited when the primary tank inductor transitions from the charging mode to the discharging mode. In many cases, the secondary tank inductor is a transmit coil of a transmitter of a wireless power transfer system.

Abstract: Disclosed are devices, systems, and methods for reducing common mode noise induced in wireless charging circuits of electronic devices. For an electronic device having an inductive receiving coil near an electric shielding layer, differences in parasitic capacitances of the loops of the inductive receiving coil with an electric shielding layer can induce common mode noise. Common mode noise is reduced by a noise-reduction capacitor from the inductive receiving coil to the electric shielding layer together with a grounding resistor from the electric shielding layer to a common ground of the wireless charging circuit.

Abstract: This disclosure relates to improved designs for phase-shift power converters, and, in particular, full bridge converters. Phase-shift power converters may lose Zero-Voltage-Switching (ZVS) under some load conditions, e.g., light load conditions—which can result in large switching losses. In order to avoid these losses, additional LC tank circuits may be added into the system to generate an amount of negative current needed to maintain ZVS. However, permanently adding such LC tank circuits into the system will reduce the system's efficiency. By intelligently adjusting the number (and particular combination) of LC tank circuits included in the system at a given time, ZVS may be maintained under all load conditions, while the impact of the additional LC tank circuits on the converter's overall efficiency may be limited, e.g., by employing the minimum number of LC tank circuits for the minimum amount of time needed to maintain ZVS.

Abstract: A wireless power transmitting device transmits wireless power signals to a wireless power receiving device by supplying drive signals with a duty cycle to a wireless power transmitting coil. The wireless power receiving device has a rectifier and a wireless power receiving coil that receives wireless power signals having the duty cycle from the wireless power transmitting device. The rectifier is coupled to an integrated circuit such as a battery charger integrated circuit. The amount of current drawn by the integrated circuit from the rectifier is adjustable. During operation, control circuitry in the wireless power receiving device sets the current to multiple different values while using sensor circuitry to measure output power from the rectifier. A satisfactory value for the duty cycle can be identified by adjusting the duty cycle while observing when peaks in the output power arise as a function of the different current values.

Abstract: A transmitter device is configured to transfer energy to multiple receiver devices. The transmitter device includes multiple transmitter coils, and a shared power converter is coupled to each transmitter coil. The shared power converter includes a leading half bridge and multiple trailing half bridges. Each transmitter coil is coupled between the leading half bridge and a respective one of the trailing half bridges. The shared power converter is dynamically configurable in that the leading half bridge may be coupled to multiple trailing half bridges when energy is to be transferred wirelessly to two or more receiver devices. The leading half bridge simultaneously operates with each trailing half bridge as an independent full-bridge phase shift inverter. A signal supplied to each transmitter coil is independently regulated by controlling a phase shift of a respective trailing half bridge with respect to the leading half bridge.

Abstract: A driver circuit provides current to a light source from a resonant tank having a single inductive element. The driver circuit is coupled to DC power source having a power rail and a ground, and includes a power inverter providing AC input to the tank, which further includes a DC blocking capacitor and a primary winding of the inductive element coupled in series between the output of the inverter and the ground. A leakage inductance of the inductive element provides resonant inductance for the tank. The inductive element further distributes power output from the resonant tank to a plurality of secondary windings coupled to an output rectifier. A resonant capacitor coupled across output ends of the secondary windings provides resonant capacitance for the tank. The output voltages across the secondary windings are clamped to a value based in part on a turns ratio between respective secondary windings.

Abstract: A wireless power transmitting device may have an array of transmitting coils to transmit power wirelessly to a wireless power receiving device having an array of wireless power receiving coils. The receiving device may have a rectifier that receives alternating-current signals from the wireless power receiving coils and provides corresponding rectified direct-current voltage signals to a capacitor and other circuitry. The rectifier circuitry may include bridge circuits each of which is coupled between a respective coil in the array of wireless power receiving coils and the capacitor. The wireless power transmitting coils may be arranged in a hexagonally tiled array. The wireless power receiving coils may include first, second, and third coils that are aligned with respective vertices in an equilateral triangle having sides with lengths equal to half of the center-to-center spacing of the hexagonally tiled transmitting coils.

Abstract: A wireless power transmitting device may have control circuitry that supplies drive signals to a coil to produce wireless power signals. The wireless power receiving device may have a coil that receives the transmitted wireless power signals from the wireless power transmitting device. The wireless power receiving device may have a rectifier that rectifies signals received by the coil in the wireless power receiving device and that provides a rectified voltage to a capacitor. A charger in the wireless power receiving device may charge a battery in the device using the rectified voltage. When it is desired to convey information to the wireless power transmitting device, the wireless power transmitting device may cease the transmission of wireless power and the wireless power receiving device may modulate transistors in the rectifier to transmit data to the wireless power transmitting device.

Abstract: This disclosure relates to improved designs for phase-shift power converters, and, in particular, full bridge converters. Phase-shift power converters may lose Zero-Voltage-Switching (ZVS) under some load conditions, e.g., light load conditions—which can result in large switching losses. In order to avoid these losses, additional LC tank circuits may be added into the system to generate an amount of negative current needed to maintain ZVS. However, permanently adding such LC tank circuits into the system will reduce the system's efficiency. By intelligently adjusting the number (and particular combination) of LC tank circuits included in the system at a given time, ZVS may be maintained under all load conditions, while the impact of the additional LC tank circuits on the converter's overall efficiency may be limited, e.g., by employing the minimum number of LC tank circuits for the minimum amount of time needed to maintain ZVS.

Abstract: This disclosure relates to power converters capable of providing multiple output voltage levels. With respect to USB-C adapter design, the converter's output may need to be changed between different voltage levels, e.g., a low voltage (such as 5V, 10V), an intermediate voltage (such as 12V, 20V), or a high voltage (such as 20V, 40V)—based on the charging device's request. By using a tapped-winding transformer, the turns-ratio of a flyback transformer may be intelligently selected for high output voltage ranges, thus enabling the duty cycle to be kept the same for the low and intermediate voltage output levels. The flyback converter would then only need to accommodate the intermediate and high output voltages. For high output voltages, a switch may be activated to put the two windings of the transformer in series; for lower output voltages, the switch may be turned off, such that only one winding is used.

Abstract: A light fixture includes a surge protection circuit for a non-isolated DC-DC converter. The converter is coupled to a circuit ground and further provides output power to a light source chassis configured to house a light source. The chassis is coupled to earth ground. The surge protection circuit includes a voltage triggering device having a breakdown voltage value and coupled to either the circuit ground or an output of the converter. A first capacitor is coupled in series between the voltage triggering device and the earth ground, and a second capacitor is coupled in parallel with the voltage triggering device. The first capacitor is configured with a sufficiently large capacitance wherein a voltage across the first capacitor, and likewise a voltage between the chassis and the earth ground, is effectively clamped to a light source threshold value during a surge condition.