System General Corporation

Fairchild Semiconductor Corporation

Fairchild (taiwan) Corporation

Semiconductor Components Industries, LLC

Chunghwa Picture Tubes, Ltd.

Jung-Sheng Chen

Ta-Yung Yang

Li Kuei Lin

Chih-Hsien Hsieh

Yue-Hong Tang

Chin-Yen Lin

Kai-Fang Wei

Hangseok Choi

Zhibo Tao

Chuh-Ching Li

Ju-Hyun Kim

Ming-Dou Ker

Young-Bae Park

Chien-Yuan Lin

Chen-Hua Chiu

Yung-I Chang

Chun-Yuan Hsu

Jian-Ming Fu

Eui-Soo Kim

Sheng-Fu Hsu

Yuan-Pu Lee

Keun-Eul Hong

Zhi-Bo Tao

David Jay Kunst

A switched-mode power supply with near valley switching includes a quasi-resonant converter. The converter includes a switch element that is turned on not only at the valley, but also in a window range of &#x394;tclose to the valley, where the voltage across the switch element is at its minimum. This advantageously reduces switching loss and maintains a balance between efficiency and frequency variation.

Power supply with near valley switching in near valley window time period

Power supply with near valley switching

A pollution detection circuit and a pollution detection method for data lines are provided. The pollution detection circuit and the method detect an impedance of at least one data terminal for detecting the pollution occurring at the data terminal or the data lines. The pollution occurring at the data terminal or the data lines is confirmed when the impedance is low.

Pollution detection circuit for data lines and method thereof

A control circuit of a power supply is provided. The control circuit includes a circuit and a PWM circuit. The circuit generates a limit signal in response to an output voltage of the power supply for limiting a switching current of a transformer of the power supply. The PWM circuit generates a switching signal in response to a feedback signal and the limit signal for switching the transformer and regulating the output voltage of the power supply. A level of the feedback signal is related to a level of the output voltage of the power supply. The output voltage of the power supply is programmable.

Programmable current limit circuit for a programmable power supply

The present invention proposes a method for controlling an adaptive power converter. The method comprises: generating an output-sense signal by sampling a reflected voltage of a transformer; receiving a feedback signal related to an output power of the adaptive power converter; generating a clock signal in response to the feedback signal and the output-sense signal; generating a switching signal for switching the transformer and regulating an output voltage of the adaptive power converter. The reflected voltage is correlated to the output voltage of the adaptive power converter. The switching signal is generated in response to the feedback signal. The frequency of the switching signal is determined by the clock signal. The frequency of the switching signal is decreased in response to a decrement of the feedback signal.

Method and apparatus of frequency modulation for power saving of adaptive power converter

An adaptive sampling circuit of the power converter according to the present invention comprises a sample-and-hold unit and a signal-generation circuit. The sample-and-hold unit is coupled to a transformer to generate a feedback signal by sampling a demagnetized voltage of the transformer in response to a sample signal. The signal-generation circuit generates the sample signal in response to a magnetized voltage of the transformer, the demagnetized voltage of the transformer, a switching signal and a code. The sample signal is used for sampling the demagnetized voltage. The feedback signal is correlated to an output voltage of the power converter. The switching signal is generated in response to the feedback signal for switching the transformer and regulating the output of the power converter. The adaptive sampling circuit is used to precisely measure the demagnetized voltage of the transformer without the limitation of the transformer design.

Adaptive sampling circuit for detecting the demagnetized voltage of the transformer

A control circuit of a power converter is provided. It comprises a voltage detection circuit detecting a reflected signal for generating a voltage-loop signal. A current detection circuit detects a current of a transformer for generating a current-loop signal. An oscillator generates an oscillation signal in accordance with an output load of the power converter. A PWM circuit generates a switching signal according to the voltage-loop signal, the current-loop signal and the oscillation signal for regulating an output of the power converter. A load detection circuit receives a detection signal through an signal-transfer device for increasing a switching frequency of the switching signal. The detection signal is generated once the output is lower than a low-voltage threshold. The oscillation signal determines the switching frequency of the switching signal. The control circuit reduces the voltage drop of the output when the output load is changed.

Control circuit with fast dynamic response for power converters

A sampling circuit of the power converter according to the present invention comprises an amplifier circuit receiving a reflected voltage for generating a first signal. A first switch and a first capacitor are utilized to generate a second signal in response to the reflected voltage. A sample-signal circuit generates a sample signal in response to a falling edge of a switching signal. The switching signal is generated in accordance with a feedback signal for regulating an output of the power converter. The feedback signal is generated in accordance with the second signal. The sample signal is utilized to control the first switch for sampling the reflected voltage. The sample signal is disabled once the first signal is lower than the second signal. The sampling circuit precisely samples the reflected voltage of the transformer of the power converter for regulating the output of the power converter.

Sampling circuit for measuring the reflected voltage of transformer for power converter

A control circuit of a flyback power converter according to the present invention comprises a low-side transistor, an active-clamper, a high-side drive circuit, and a controller. The low-side transistor is coupled to switch a transformer. The active-clamper is coupled in parallel with the transformer. The high-side drive circuit is coupled to drive the active-clamper. The controller generates a switching signal and an active-clamp signal. The switching signal is coupled to drive the low-side transistor. The switching signal is generated in accordance with a feedback signal for regulating an output of the flyback power converter. The active-clamp signal is coupled to control the high-side drive circuit and the active-clamper. The active-clamp signal is generated in response to a demagnetizing time of the transformer. The pulse number of the active-clamp signal is less than the pulse number of the switching signal in a light load condition.

Adaptive active clamp of flyback power converter with high efficiency for heavy load and light load

A controller of the power converter according to the present invention comprises a gate driver. The gate driver generates a gate-drive signal. The gate-drive signal is coupled to drive a power transistor to switch a transformer of the power converter for regulating an output of the power converter. The gate driver has a charge-pump circuit for charging pump a voltage level of the gate-drive signal. Therefore, the gate-drive signal can fully turn on the power transistor.

Transistor gate driver with charge pump circuit for offline power converters

A sampling circuit of the power converter according to the present invention comprises an amplifier circuit receiving a reflected voltage for generating a first signal. A first switch and a first capacitor are utilized to generate a second signal in response to the reflected voltage. A sample-signal circuit generates a sample signal in response to the disable of a switching signal. The switching signal is generated in accordance with a feedback signal for regulating an output of the power converter. The feedback signal is generated in accordance with the second signal. The sample signal is utilized to control the first switch for sampling the reflected voltage. The sample signal is disabled once the first signal is lower than the second signal. The sampling circuit precisely samples the reflected voltage of the transformer of the power converter for regulating the output of the power converter.

Sampling circuit for measuring reflected voltage of transformer for power converter operated in DCM and CCM

The present invention provides a control circuit for a power converter. The control circuit includes a switching circuit, an input-voltage detection circuit and a current-limit threshold. The switching circuit generates a switching signal coupled to switch a transformer of the power converter for regulating an output of the power converter in response to a feedback signal. The input-voltage detection circuit generates a control signal when an input voltage of the power converter is lower than a low-input threshold. The feedback signal is generated in response to the output of the power converter. A maximum duty of the switching signal is increased in response to the control signal. The current-limit threshold is for limiting a maximum value of a switching current flowing through the transformer. The current-limit threshold is increased in response to the control signal. An input of the power converter doesn't connect with electrolytic bulk capacitors.

Control circuit for offline power converter without input capacitor

A control circuit of the power converter according to the present invention comprises a feedback circuit, an output circuit and an adaptive clamping circuit. The feedback circuit generates a feedback signal in accordance with an output of the power converter. The output circuit generates a switching signal in accordance with the feedback signal for regulating the output of the power converter. The adaptive clamping circuit limits the level of the feedback signal under a first level for a first load condition. The feedback circuit determines a slew rate of the feedback signal for increasing the level of the feedback signal from the first level to a second level. The adaptive clamping circuit is disabled and the level of the feedback signal can be increased to the second level for a second load condition.

Control circuit for controlling the maximum output current of power converter and method thereof

A controller of a power converter is provided. The controller includes a feedback circuit, an output circuit, and a clamping circuit. The feedback circuit generates a feedback signal in accordance with output of the power converter. The output circuit generates a switching signal in accordance with the feedback signal for regulating the output of the power converter. The clamping circuit limits the feedback signal under a first level for a first load condition and limits the feedback signal under a second level for a second load condition. The clamping circuit includes a timer circuit. The timer circuit determines a slew rate of the feedback signal for increasing the feedback signal from the first level to the second level, and the second level is higher than the first level.

Controller and power converter using the same for clamping maximum switching current of power converter

An adaptive filter circuit for sampling a reflected voltage of a transformer of a power converter includes a first switch for receiving the reflected voltage, a resistor having a first terminal and a second terminal, the first terminal of the resistor being coupled to the first switch, a capacitor coupled to the second terminal of the resistor for holding the reflected voltage, and a second switch coupled to the resistor in parallel, wherein the resistor and the capacitor develop a filter for sampling the reflected voltage which is sampled without filtering by the filter in a first period during a disable period of a switching signal and also sampled with filtering by the filter in a second period during the disable period of the switching signal.

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Kaohsiung, Taiwan

Jung-Sheng Chen