An integrated circuit for a power supply circuit. The integrated circuit includes an oscillator circuit configured to output an oscillator voltage that rises with a predetermined slope from a first voltage, upon an inductor current of the power supply circuit becoming smaller than a first predetermined value, an error voltage output circuit configured to output an error voltage corresponding to a difference between a reference voltage and a feedback voltage corresponding to the output voltage, a drive circuit configured to turn on and off a transistor of the power supply circuit respectively upon the inductor current becoming smaller than the first predetermined value, and upon the oscillator voltage reaching a second voltage that is based on the error voltage, and an output circuit configured to change the first and/or second voltage based on a rectified voltage obtained by full-wave rectification of the AC voltage, and to output the changed voltage.

According to the present embodiment, a DC transformation system includes a rectifier, a first power conversion device, a second power conversion device, and a control device. The rectifier rectifies AC power supplied from an AC power source and outputs a first DC voltage. The first power conversion device is connected in series to the rectifier and outputs a second DC voltage. The second power conversion device is connected in parallel to the rectifier and converts power supplied from the rectifier to supply the converted power to the first power conversion device. The control device controls the first power conversion device to cause an addition/subtraction voltage of the first DC voltage and the second DC voltage to be a predetermined voltage.

A dimming circuit includes a DC/DC conversion unit and a control module. The control module provides a switching period reference, and samples an input voltage and an output voltage. The control module calculates a turn-on time according to the input voltage, the output voltage and a reference current signal. The control module generates a variation period signal which is cyclically-changed. The variation period signal is combined with the switching period reference or the turn-on time. Consequently, a pulse width modulation signal cyclically changed is generated by the switching period reference, the turn-on time and the variation period signal. Since the switching periods is cyclically changed, the average of the output current is close to the ideal value.

Systems and methods are provided for regulating a power conversion system. An example system controller includes: a detection component configured to receive an input voltage related to a diode connected to an inductor and output a first signal at a first logic level in response to the input voltage being larger than a predetermined threshold, a control logic component configured to receive the first signal, process information associated with the first signal, and output a modulation signal related to a modulation frequency in response to the first signal being at the first logic level, and a driving component configured to receive the modulation signal and output a drive signal to open and close a first switch at the modulation frequency.

A power supply converter can include: an AC-DC linear circuit configured to rectify an AC input voltage to generate a DC voltage, and to transfer the input energy to an output terminal thereof during at least part of a time interval when the DC voltage is greater than an output voltage thereof, in order to generate a first output voltage and a first output current; and a conversion circuit configured to convert the first output voltage to a second output voltage, and to convert the first output current to a second output current for a load.

A switching mode power supply disables a ZCD function when the AC input voltage has a voltage value close to a voltage value of the output voltage, so that instable zero crossing detection issues are eliminated.

A controller for a power converter, a corresponding power converter and a corresponding method are provided. After reaching a first maximum voltage, power flowing is gradually reduced, and later the current provided to an output capacitor is gradually ramped up.

A control circuit is provided for a buck converter that includes at least an inductor coupled to an output of the buck converter. The control circuit includes a power switch configured for coupling to a line voltage and configured for charging the inductor, an input line voltage sampling circuit, and a constant-voltage (CV) and constant-current (CC) control module coupled to the power switch. During a charging period of the inductor, the CV and CC control module is configured to control the power switch to provide a constant output current by maintaining a constant peak inductor current, even when the input line voltage changes. During a discharging period of the inductor, the CV and CC control module is configured to monitor the sensed output voltage to control the power switch to provide a constant output voltage.

In described examples, a Phase Regulated Power Supply includes a low output DC logic power supply, a voltage divider to sample the input AC waveform, one or more comparators, digital logic, and a switching transistor. It can include a Full Wave Rectifier and one or more capacitors, inductors and opto-isolators. In the most basic form, Alternating Current (AC) power is switched directly to a load when the AC instantaneous voltage is between a low and high set-point. Voltage is regulated by controlling the high set-point. Current through the load is regulated by briefly extinguishing the AC input from the load when the load current exceeds a set parameter. Voltage output to the load is adjustable from zero volts to the AC peak voltage. Current through the load is adjustable from zero amps to the AC circuit breaker limit.

A system and method for high speed switching comprises receiving voltage inputs at a bridge rectifier, generating a control signal from a transistor, and driving a gate of a field effect transistor (FET) via the control signal of the transistor, wherein a source of the FET is connected to a negative output of the bridge rectifier and a drain of the FET is connected to a positive output of the bridge rectifier through a load. The system and method further comprises limiting current flowing to the gate of the FET through first and second resistors and first and second diodes connecting the voltage inputs to the gate of the FET and limiting voltage to the gate of the FET below a maximum voltage rating of the FET by a Zener diode connected to the gate of the FET.