Abstract: Apparatus and method for a power converter with feed-forward voltage compensation to enable a PFC circuit are proposed. A voltage divider and a feedback unit output a compensation voltage and a feedback voltage in response to an input voltage and an output voltage, respectively. The feedback voltage is compensated by the compensation voltage through an operation unit. A comparator activates the PFC circuit within a predetermined input power range based on the already compensated feedback voltage. The proposed power converter can always activate the PFC circuit before the input power reaches 75 W regardless of any variation of the input voltage.

Abstract: An apparatus for a power supply with brownout protection and the method thereof are proposed. As a brownout condition occurs, the apparatus informs at least one microprocessor to process the shutdown process timely. The apparatus includes a power factor correction (PFC) circuit, and a bus capacitor generating a bus voltage by receiving an input voltage via the PFC circuit, and a PWM circuit generating multiple output voltages for the microprocessor, and a supervisor circuit generating a power-good signal in response to a proportional bus voltage, and a brownout circuit for disabling the boosting operation of the PFC circuit under a brownout condition. When the boosting operation is disabled, the bus voltage starts to fall. As the proportional bus voltage is lower than a threshold voltage, the supervisor circuit generates the power-good signal. Therefore, the microprocessor can process the shutdown procedure timely.

Abstract: An integrated control circuit for a resonant power converter includes a minimum-frequency programming circuit connected a first resistor to program a minimum switching frequency of the power converter. A feedback circuit is coupled to a feedback terminal to receive a feedback signal for generating an adjustment signal. A maximum-frequency programming circuit connects a second resistor to determine a maximum switching frequency in response to the adjustment signal. An oscillator is coupled to the minimum-frequency programming circuit and the maximum-frequency programming circuit to generate an oscillation signal for determining the switching frequency of the power converter. A feed-forward circuit is connected to a feed-forward terminal to receive a feed-forward signal represents the input voltage of the power converter. The switching frequency is increased in response to decrease of the feedback signal, and the switching frequency is increased in response to the increase of the feed-forward signal.

Abstract: Apparatus and method for a power converter with feed-forward voltage compensation to enable a PFC circuit are proposed. A voltage divider and a feedback unit output a compensation voltage and a feedback voltage in response to an input voltage and an output voltage, respectively. The feedback voltage is compensated by the compensation voltage through an operation unit. A comparator activates the PFC circuit within a predetermined input power range based on the already compensated feedback voltage. The proposed power converter can always activate the PFC circuit before the input power reaches 75 W regardless of any variation of the input voltage.

Abstract: An apparatus for a power supply with brownout protection and the method thereof are proposed. As a brownout condition occurs, the apparatus informs at least one microprocessor to process the shutdown process timely. The apparatus includes a power factor correction (PFC) circuit, and a bus capacitor generating a bus voltage by receiving an input voltage via the PFC circuit, and a PWM circuit generating multiple output voltages for the microprocessor, and a supervisor circuit generating a power-good signal in response to a proportional bus voltage, and a brownout circuit for disabling the boosting operation of the PFC circuit under a brownout condition. When the boosting operation is disabled, the bus voltage starts to fall. As the proportional bus voltage is lower than a threshold voltage, the supervisor circuit generates the power-good signal. Therefore, the microprocessor can process the shutdown procedure timely.

Abstract: An automatic balance adjusting device for an AC power supply is provided between the AC current output terminals of an AC power supply and its feedback control circuit. The device uses a two-level filter to extract the DC component of an AC output signal. The DC error is accumulated and amplified by an integrator and converted from a voltage form to a current form. Through a photo coupler designed for the separation purpose, the error signal is sent back to the feedback control circuit to perform compensation. Thus, the device can achieve the purpose of automatically balancing the positive and negative half-cycle waveform of the output signal.