A system and method for snubbing transformer leakage energy in a power supply having a transformer and a main switch, in which leakage energy is stored in a capacitor as stored leakage energy when the main switch is turned off, and the stored leakage energy is transferred to the transformer through an inductor when the main switch is turned on.

The present disclosure provides a charging system and method and a power adapter. The system includes: a battery; a first rectification unit, configured to output a voltage with a first pulsating waveform; a switch unit, configured to modulate the voltage with the first pulsating waveform; a transformer, configured to output a voltage with a second pulsating waveform according to the modulated voltage; a second rectification unit, configured to rectify the voltage with the second pulsating waveform to output a voltage with a third pulsating waveform; and a control unit, configured to output the control signal to the switch unit to decrease a length of a valley of the voltage with the third pulsating waveform such that a peak value of a voltage of the battery is sampled.

In an embodiment, a voltage comparator includes: a first switch having a conduction terminal coupled to an internal node that is coupled to an output of the voltage comparator; a current source; a capacitor; and a second switch connected in parallel with the capacitor, wherein the current source, the capacitor, and the first switch are coupled in series.

A power supply apparatus generates an output voltage. A boost circuit boosts a voltage supplied from a reference voltage source and generates a first power supply voltage. A processor controls switching the boost circuit on and off. A first transistor is connected to the first power supply voltage. A second transistor is connected to a collector of the first transistor. A resistance element is connected to a collector of the second transistor. A voltage source is connected to the resistance element and generates a second power supply voltage. A collector voltage, which is an output voltage, of the second transistor is controlled by controlling an amount of base current of the first transistor.

A system including: a first regulator having a first input voltage and a first output voltage; a second regulator having a second input voltage and a second output voltage; a first driver circuit coupled to the first regulator and a switch, wherein the first driver circuit is configured to drive the switch based on the first output voltage; a second driver circuit coupled to the second regulator and the switch, wherein the second driver circuit is configured to drive the switch based on the second output voltage; a driver controller coupled to the first driver circuit and the second driver circuit, wherein the driver controller is configured to select one of the first driver circuit and the second driver circuit to drive the switch based on a control signal; and a switch node coupled to the switch, wherein a switch node voltage at the switch node is a function of the switch being turned on and off.

A power supply circuit for measuring transient thermal resistances includes an inverter circuit provided on a primary side of a transformer and controlled by a PWM signal, a rectifier circuit provided on a secondary side of the transformer and including a DC reactor, and a control circuit controlling the PWM signal so as to output a pulsed output current from the rectifier circuit to a semiconductor device to be measured. The control circuit sets a first PWM frequency at rising timing of the output current, and sets a second PWM frequency when a predetermined time t1 elapses from the rising timing of the output current. The control circuit sets the first PWM frequency higher than the second PWM frequency.

A control circuit for controlling power switch in switching power supply circuit. The optimization circuit comprises an adaptive amplitude jitter generating circuit, a comparison circuit and a trigger circuit. The adaptive amplitude jitter generating circuit is used to generate a periodic amplitude jitter signal according to the feedback voltage signal indicative of the output of the switching power supply circuit. The comparison circuit is used to compare the sampled voltage signal with periodic amplitude jitter signal, and generate an output signal with periodic fluctuations. The trigger circuit is used for outputting the control signal for driving the power switch according to the output signal with periodic fluctuations and the clock signal.

An isolated switching power converter is presented. The isolated switching converter includes a transformer, a secondary-side switch and a secondary-side controller. The transformer has a primary winding coupled to an input, a first secondary winding coupled to a first output for providing a first output voltage, and a second secondary winding coupled to a second output for providing a second output voltage. The secondary-side switch is coupled to the second secondary winding. The secondary-side controller compares the second output voltage with a first reference voltage and generates a control signal based on the comparison to operate the secondary-side switch.

A flyback converter with improved over-voltage protection (OVP) functionality, which includes a primary winding arranged to receive an input voltage, a secondary winding coupled to the primary winding and connected to a rectifier circuit to generate DC output voltage, a primary side regulating controller, an auxiliary winding arranged to provide electric power to the primary side regulating controller, an external detection circuit connected between the auxiliary winding and the primary side regulating controller, an internal detection circuit arranged inside the primary side regulating controller and coupled to the external detection circuit by detecting the current value flowing through the external detection circuit and comparing it with a predetermined current value of the internal detection circuit to enable or disable an OVP circuit to protect the primary side regulating controller, and a switching device arranged to receive on/off signals generated for regulating current flowing through the primary winding.

Disclosed herein is an improved flyback converter that separates the magnetic components of the converter into a transformer and a separate, discrete energy storage inductor. This arrangement can improve the operating efficiency of the converter by reducing the commutation losses as compared to a conventional flyback converter. The magnetic components may be constructed on separate magnetic cores or may be constructed on magnetic cores having at least one common element, thereby allowing for at least partial magnetic flux cancellation in a portion of the core, reducing core losses.