A bidirectional DC-DC converter with three or more ports is described along with a method of operation thereof. The converter utilizes a common transformer for all ports and allows for power transfer from any port to any or all of the remaining ports. The converter may utilize a controller which implements variable-frequency control, delay-time control, and/or phase-delay control to achieve power transfer as desired between the converter ports. In some cases, power transfer between ports can operate similar to a series-resonant converter or a dual active bridge converter.

A system for facial movement detection with reduced size and reduced cost by employing a novel resonant drive and sampling scheme is disclosed. An example battery operated system includes a driver circuit, an LC resonance circuit formed by an inductor circuit and a capacitance from an antenna, and a sample and hold circuit. The driver circuit can be configured by a controller to generate a drive signal for the LC resonance circuit, which has a resonant frequency that changes as the capacitance of the antenna varies responsive to facial movements of the user. The sample and hold circuit samples the output of the LC resonance circuit responsive to a falling edge of the drive signal for the LC resonance circuit, wherein an output of the sample and hold circuit is a sampled sense signal that may be further processed to detect facial movements of the user.

This application provides a wireless charger and a control method. The wireless charger includes a class-E power amplifier and a tunable impedance circuit that is connected to an output end of the class-E power amplifier. The class-E power amplifier includes a switching transistor and a tunable capacitance circuit that is parallelly connected to the switching transistor. The wireless charger further includes a control unit, configured to obtain a constraint condition of the class-E power amplifier; determine N1 target equivalent load impedances of the class-E power amplifier based on the constraint condition; and adjust a capacitance value of the tunable capacitance circuit in the class-E power amplifier, and adjust an impedance value of the tunable impedance circuit, to enable an equivalent load impedance of the class-E power amplifier to match one of the N1 target equivalent load impedances.

A method for reducing current ripple at an output of a power supply includes sensing an alternating current (AC) input voltage waveform; determining a correction factor for a switching frequency of the power supply based on the sensed AC input voltage; and applying the correction factor to the switching frequency of the power supply to modify the power supply switching frequency. A modification of the switching frequency synchronizes the switching frequency of the power supply to the AC input voltage waveform.

A control circuit for a resonant converter, can include: a feedforward circuit configured to generate a feedforward current; a charge feedback circuit configured to receive a resonant current sampling signal representing a resonant current of the resonant converter in a first mode to generate a charge feedback signal, and to receive the resonant current sampling signal and the feedforward current together to generate the charge feedback signal in a second mode; and a driving control circuit configured to generate driving signals according to the charge feedback signal and a first threshold signal, in order to control switching states of power transistors of the resonant converter, where the first threshold signal is generated according to an error compensation signal representing an error information between a feedback signal of an output signal of the resonant converter and a reference signal.

A controller IC for a resonant switched capacitor converter includes a drive circuit and a frequency controller. The frequency controller controls a switching frequency based on an output voltage of the resonant switched capacitor converter.

A voltage converter includes a capacitive voltage conversion circuit, an output capacitor, an inductor, a current detector, and a controller. The capacitive voltage conversion circuit includes switches, at least one flying capacitor, and an intermediate capacitor at an output portion. The current detector detects a current flowing in the inductor. The controller controls the switches in the capacitive voltage conversion circuit to change between at least two states by comparing the current flowing in the inductor to a threshold current.

A power conversion circuit includes an input positive terminal, an input negative terminal, an output positive terminal, an output negative terminal, a first switch bridge arm, a first resonant branch, a capacitor branch, an output inductor unit and an output capacitor. The input negative terminal is electrically connected with the output negative terminal. The first switch bridge arm is electrically connected between the input positive terminal and the input negative terminal. The first switch bridge arm includes a first switch, a second switch, a third switch and a fourth switch. The first switch and the second switch are electrically connected with a first node. The second switch and the third switch are electrically connected with a second node. The third switch and the fourth switch are electrically connected with a third node. The first resonant branch is electrically connected between the first node and the third node.

An integrated circuit (IC) assembly includes a first power stage adapted to receive an input voltage and a second power stage adapted to provide an isolated output voltage. The IC also includes a transformer coupled between the first and second power stages. The IC further includes a detuning circuit coupled to the transformer, and a receiver circuit coupled to the first power stage. The receiver circuit includes an integrator configured to integrate a switching signal within the first power stage.

An inductive power outlet is disclosed. The inductive power outlet has a primary inductor, for wirelessly powering an inductive power receiver. The inductive power outlet has a secondary inductor. The primary inductor and the secondary inductor form a resonant frequency. The inductive power outlet comprises a driver generating an oscillating voltage to the primary coil at a frequency higher than the resonant frequency. The inductive power outlet comprises a signal detector. The signal detector comprises a peak detector configured to detect voltage peaks across the primary inductor or current peaks of a current supplied to the primary inductor. The signal detector comprises a processor configured to determine a frequency of either the voltage peaks or the current peaks.