A regulated power supply includes a capacitively isolated feedback circuit and a pulse width modulator (PWM) operable to produce a plurality of pulses at an output and receive a sampled voltage at a feedback input thereof. The capacitively isolated feedback circuit includes a capacitively isolated gate drive circuit directly coupled to the PWM output and configured to produce a plurality of isolated pulses from the plurality of pulses received from the PWM output. The capacitively isolated feedback circuit also includes a forward converter feedback circuit, which includes a switching transistor directly coupled to the capacitively isolated gate drive circuit for receiving the plurality of isolated pulses at a gate of the switching transistor and a feedback transformer directly coupled to the PWM for providing the sampled voltage at the feedback input. The plurality of isolated pulses causes the feedback transformer to sample a load voltage as the sampled voltage.

A semiconductor circuitry includes a plurality of diodes and a first resister. The semiconductor circuitry is arranged in a circuit in which a first transistor and a second transistor are connected to a power supply in series, and the circuit outputs a voltage applied to an external load. The plurality of diodes which are connected in parallel with a first transistor and a second transistor, are diodes to which a reverse bias is applied by the power supply, and are connected in series with each other, and in which each breakdown voltage is lower than a voltage of the power supply and the sum of breakdown voltage of all these diodes is higher than the voltage of the power supply. The first resistor which connects a connection node between the plurality of diodes and a connection node between the first transistor and the second transistor.

This specification discusses the concept of energy injection in a resonant circuit with initial conditions which is part of almost all of the present topologies. It presents in detail several methods of energy injection in a resonant circuit with initial conditions and how it applies to different topologies. It patent presents also a simple and economical method of driving the clamp switch in a flyback topology operating in discontinuous mode and a bias circuit in a flyback topology wherein the output voltage varies over a large range.

A multi-input voltage converter includes an output circuit, a first conversion circuit, and a second conversion circuit. The first conversion circuit includes a first voltage receiving module, a first transformer, a first switch. The second conversion circuit includes a second voltage receiving module, a second switch. When the second voltage receiving module receives the second input voltage, the second switch is turned on to operate, and the output circuit outputs the output voltage.

Reverse currents are prevented using existing components, like a primary-side current transformer. A power supply includes an isolation transformer, a switch, a synchronous rectifier, a smoother, a controller with a signal generator circuit that outputs main drive signals for main switching elements of the switch and drive signals for synchronous rectifier elements of the synchronous rectifier, and a current detector that has a current transformer, detects a current flowing to the switch, and outputs an output current detection signal. The controller includes an OR circuit that generates an OR signal for the main drive signals and a reverse current determination circuit that determines whether a reverse current has occurred based on the OR signal and the output current detection signal. When the occurrence of a reverse current has been determined, outputting of the main drive signals and the drive signals is stopped.

A power supply device includes an energy tank, a discharging and starting circuit, a fuse, a bridge rectifier, a transformer, a power switch element, an output stage circuit, and a controller. The energy tank includes an NTC (Negative Temperature Coefficient) thermistor. The energy tank absorbs a burst high voltage, and converts the burst high voltage into thermal energy. The discharging and starting circuit is coupled to the energy tank. The discharging and starting circuit includes a bypass path. When the resistance of the NTC thermistor is smaller than a threshold value, the bypass path is enabled, such that the energy tank is coupled through the bypass path to a ground and a ground voltage. The bridge rectifier is coupled through the fuse to the energy tank. The discharging and starting circuit is selectively configured to enable the controller.

A secondary controller applied to a secondary side of a power converter includes a control signal generation circuit. The control signal generation circuit is coupled to an output terminal of the secondary side of the power converter for detecting an output voltage of the secondary side and enabling a pulse signal to a signal source of the secondary side of the power converter, wherein the signal source enables a turning-on signal according to the pulse signal. The turning-on signal is coupled to a primary-side auxiliary winding of the power converter through a secondary-side auxiliary winding of the power converter to make the primary-side auxiliary winding generate a voltage, and a primary controller of a primary side of the power converter makes the primary side of the power converter be turned on according to the voltage.

Disclosed herein is a control circuit of an isolated power supply including a first transformer and a primary-side transistor connected to a primary winding of the first transformer. The control circuit includes a timing generator that generates a timing signal with reference to an edge of a switching signal generated on a secondary side of the isolated power supply, a sampling circuit that, in response to the timing signal, samples an electric signal to be monitored, the electric signal to be monitored being an electric signal on the secondary side of the isolated power supply, and a feedback controller that, based on an output of the sampling circuit, generates a primary-side pulse signal to be supplied to the primary-side transistor.

A load control device for controlling the amount of power delivered to an electrical load (e.g., an LED light source) includes first and second semiconductor switches, a transformer, a capacitor, a controller, and a current sense circuit operable to receive a sense voltage representative of a primary current conducting through to a primary winding of the transformer. The primary winding is coupled in series with a semiconductor switch, while a secondary winding is adapted to be operatively coupled to the load. The capacitor is electrically coupled between the junction of the first and second semiconductor switches and the primary winding. The current sense circuit receives a sense voltage and averages the sense voltage when the first semiconductor switch is conductive, so as to generate a load current control signal that is representative of a real component of a load current conducted through the load.

A variable DC-DC converter includes a no-load voltage clamp in which a rectified, filtered, and loaded control signal drives a switch. The switch switches in a load resistance across the output terminals of the converter when the output terminals are unloaded or lightly loaded. Due to a combined rectification, smoothing, and filtering operation of the control signal circuit, the control signal provides a steady voltage of the output voltage selected by a user of the converter based on predetermined output requirements. The control signal is therefore not subject to the voltage spikes that the main output is subject to. The circuit compares the control signal to the output voltage, and switches in the load resistance when the voltage at the output rises above the control signal.