System General Corporation

Semiconductor Components Industries, LLC

Fairchild (taiwan) Corporation

Wei-Hsuan Huang

Ta-Yung Yang

Chien-Yuan Lin

Meng-Jen Tsai

Chuan-Chang Li

Chi-Chen Chung

Gwo-Hwa Wang

Ming-Chang Tsou

Rui-Hong Lu

Jenn-Yu G Lin

Cheng-Chi Hsueh

Chih-Feng Huang

Chuh-Ching Li

Chen-Hua Chiu

You-Kuo Wu

Chiu-Chih Chiang

Chien-Tsun Hsu

Cheng-Sung Chen

Jian-Ming Fu

Shao-Chun Huang

Yuan-Pu Lee

A start-up circuit to discharge EMI filter is developed for power saving. It includes a detection circuit detecting a power source for generating a sample signal. A sample circuit is coupled to the detection circuit for generating a reset signal in response to the sample signal. The reset signal is utilized for discharging a stored voltage of the EMI filter.

Start-up circuit to discharge EMI filter for power saving of power supplies

A discharge circuit for an electromagnetic interference (EMI) filter is provided. The discharge circuit includes a switch circuit, a control circuit, and a detection circuit. The switch circuit is coupled to an X-capacitor of the EMI filter. The control circuit is coupled to the switch circuit and configured to turn on the switch circuit in a predetermined period to provide a discharge path. The detection circuit is coupled to the discharge path. In the predetermined period, the detection circuit detects whether a cross point occurs between a discharge voltage signal on the discharge path and a reference voltage signal to generate a detection signal which is provided to the control circuit. When the detection circuit detects that the cross point does not occur, the control circuit continuously turns on the switch circuit according to the detection signal after the predetermined period has elapsed.

Discharge circuits of discharge paths for electromagnetic interference filters

A control circuit with deep burst mode for power converter according to the present invention comprises a load detection circuit and a PWM circuit. The load detection circuit generates a switching control signal in response to a feedback signal. The feedback signal is correlated to a load condition of the power converter. The PWM circuit generates a switching signal to regulate an output of the power converter in response to the switching control signal and the feedback signal. The control circuit performs a deep burst mode to switch the switching signal only one time during each deep burst period when the load condition of the power converter is a very light-load. Therefore, switching loss is reduced so that the power consumption of the power converter is also reduced.

Control circuit with deep burst mode for power converter

A controller with power saving for a power converter includes a delay circuit, a detection circuit, an output circuit, a counter circuit, a wake-up circuit and a PWM circuit. The delay circuit determines a delay time. The detection circuit activates the delay circuit whenever an output load of the power converter is lower than a light-load threshold. The output circuit generates a power-saving signal to cease a regulation of the power converter after the delay time ends. The regulation of the power converter is resumed once the output load increases during the regulation of the power converter is being ceased. The counter circuit coupled to the delay circuit is counted by the delay circuit to determine a sleep period. The output circuit generates the power-saving signal to cease the regulation of the power converter after the sleep period ends.

Controller with power saving for power converters and method for the same

This invention provides a control circuit for burst switching of a power converter comprising: an adaptive circuit generating an adaptive threshold in response to a feedback signal correlated to an output load of the power converter; and a switching circuit generating a switching signal to switch a transformer of the power converter in accordance with the adaptive threshold and the feedback signal for regulating an output of the power converter.

Control circuit for burst switching of power converter and method thereof

The present invention provides a power saving circuit for PWM circuit. The power saving circuit is utilized to control at least one internal circuit. The power saving circuit comprises a switching circuit which generates a switching signal. The power saving circuit controls the internal circuit in response to the switching. The power saving circuit disables the internal circuit for power saving when the switching signal is disabled.

Power saving circuit for PWM circuit

A feedback circuit with feedback impedance modulation according to the present invention comprises a compare circuit, a counter and a switching resistor circuit. The compare circuit receives a feedback signal of a power converter to compare the feedback signal with a threshold signal for generating a control signal. The feedback signal is correlated to a load condition of the power converter. The counter is coupled to the compare circuit and generates a modulation signal in response to the control signal. The switching resistor circuit is coupled to the counter and a feedback loop of the power converter for modulating a feedback impedance of the power converter in response to the modulation signal. The feedback impedance is directly modulated from a lower resistance to a higher resistance when the load condition is reduced from a half/full-load to a no/light-load. The feedback impedance is gradually modulated from a higher resistance to a lower resistance when the load condition is increased from the no/light-load to the half/full-load.

Feedback circuit with feedback impedance modulation for improving power saving

A start-up circuit with low standby power loss for power converters according to present invention comprises a first diode and a second diode coupled to an input voltage of the power converter. A start-up resistor is coupled to the join of the first diode and the second diode. A high-voltage switch is coupled to the start-up resistor to generate a power source. A control circuit generates a switching signal for switching a transformer. A detection circuit generates a disable signal in response to the input voltage to disable the switching signal. A winding of the transformer is coupled to the power source to generate the power for the power source. The high-voltage switch is turned off to cut off the start-up resistor for saving the power loss once the voltage of the power source is higher than a threshold.

Start-up circuit with low standby power loss for power converters

The present invention provides a power converter. The power converter includes a transformer, a power switch and a controller. The transformer has a primary winding, a secondary winding and an auxiliary winding. The power switch is coupled to the primary winding of the transformer to regulate the power converter. The controller has an output terminal for generating a driving signal to switch the power switch in response to a switching signal. A thermal resistor is coupled to the output terminal of the controller. The driving signal is adjusted across the thermal resistor during an off-period of the switching signal.

Method and apparatus of providing over-temperature protection for power converters

A biased current-limit circuit for limiting a maximum output power of a power converter includes an oscillator for generating a pulse signal and an oscillation signal. A waveform generator generates a waveform signal in response to the oscillation signal. A sample-hold circuit is used to sample the waveform signal to generate a hold signal in response to a switching signal. The sample-hold circuit further samples the hold signal to generate a current-limit threshold in response to a second-sampling signal. A current comparator is utilized to compare a current-sensing signal with the current-limit threshold to limit a maximum on-time of the switching signal.

Method and apparatus of providing a biased current limit for limiting maximum output power of power converters

A control circuit of a power converter for light-load power saving according to the present invention comprises a first feedback circuit coupled to an output voltage of the power converter to receive a first feedback signal. A second feedback circuit is coupled to the output voltage to receive a second feedback signal. A control circuit generates a switching signal for switching a transformer of the power converter and regulating the output voltage of the power converter in response to the first feedback signal and the second feedback signal. The switching signal is generated in accordance with the first feedback signal when an output load is high. The switching signal is generated in accordance with the second feedback signal during a light-load condition.

Growing community of inventors

Taoyuan, Taiwan

Wei-Hsuan Huang