Leadtrend Technology Corporation

Excelliance Mos Corporation

Ching-Tsan Lee

Ming-Hung Chien

Pei-Ting Yang

Mao-Shih Li

Chung-Wei Lin

Pai-Feng Liu

Ke-Wei Wu

Yang-Sheng Lin

Hsin Hung Lu

Chun-Hsin Li

Wei-Wen Ou

Chien-Chun Lu

San Yi Li

Hsiang-Feng Yu

A voltage converting circuit and a control circuit thereof are provided. The control circuit includes a comparator, a clock generator, and a boost circuit. The comparator compares an input voltage with an output voltage to generate a comparison signal. The clock generator generates a clock signal according to the comparison signal to enable the clock signal to have a first frequency in a first time interval and to have a second frequency in a second time interval. The first frequency is higher than the second frequency. The first time interval occurs before the second time interval. The boost circuit receives the clock signal, pulls up a control signal of a driving switch in the first time interval according to a first driving capability, and generates the control signal in the second time interval according to a second driving capability. The first driving capability is greater than the second driving capability.

Voltage converting circuit and control circuit thereof

A control circuit of a load switch including a charge pump circuit, an oscillator, and a current signal generator is provided. The charge pump circuit generates a control signal according to a clock signal. The load switch is turned on or turned off according to the control signal. The oscillator generates the clock signal according to a control current. The current signal generator provides a resistor string to receive a power voltage. The resistor string of the current signal generator generates a sensed current or a sensed voltage according to the power voltage. The current signal generator generates the control current according to a reciprocal of the sensed current or a square of the sensed voltage. A frequency of the clock signal is negatively related to the power voltage.

Control circuit for load switch

A power circuit including a switching circuit and a soft start control circuit is provided. A first terminal of the switching circuit is configured to receive an input voltage. A control terminal of the switching circuit receives a control signal. A second terminal of the switching circuit is configured to provide an output voltage. The soft start control circuit generates the control signal according to the output voltage and a first reference voltage to control a turn-on state of the switching circuit. The soft start control circuit switches a slope of the control signal from a first slope to a second slope after the switching circuit is turned on and when a voltage value of the control signal is equal to a second reference voltage, wherein the first slope is less than the second slope to reduce an inrush current at the time when the switching circuit is turned on.

Power circuit for reducing inrush current

A power switch circuit including first and second transistors, and a control circuit is provided. A first end of the first transistor serves as an input terminal of the power switch circuit. A second end of the first transistor is coupled to a node. A control end of the first transistor receives a first control voltage. A first end of the second transistor serves as an output terminal of the power switch circuit. A second end of the second transistor is coupled to the node. A control end of the second transistor receives a second control voltage. The control circuit detects a voltage of the node to determine a type of series connection between the first and second transistors, and generates the first and second control voltages to control a turned-on state of another of the first and second transistors after turning on one of the first and second transistors.

Power switch circuit

A power delivery controller applied to a power converter includes a voltage compensation circuit and a comparator. The voltage compensation circuit is used for generating a compensation reference voltage, receiving a response signal through a universal serial bus type-C cable, and generating a response voltage when an electronic device coupled to the universal serial bus type-C cable generates the response signal corresponding to a Biphase Mark Coding (BMC) signal, wherein the response voltage and the compensation reference voltage have information relative to an internal resistor of the universal serial bus type-C cable. The comparator is used for generating a comparison signal according to the response voltage and the compensation reference voltage, wherein the power converter transmits power to the electronic device according to a specification corresponding to universal serial bus power delivery (USB-PD) after the comparator generates the comparison signal.

Power delivery controller applied to a power converter and operation method thereof

A voltage conversion circuit and a control circuit thereof are provided. The control circuit includes a voltage selection circuit, a buffer circuit, and a pull-down switch. The voltage selection circuit receives an input voltage and an output voltage, and selects a smaller voltage value as a selected voltage from the input voltage and the output voltage. The buffer circuit receives the selected voltage, and provides the selected voltage as a reference voltage. A control end of the pull-down switch receives an enable signal, so that the pull-down switch is switched on or switched off based on the enable signal. The pull-down switch is switched on based on the enable signal, to pull down a voltage at a control end of a driver switch to the reference voltage and switch off the driver switch.

Voltage conversion circuit and control circuit thereof

A controller applied to a secondary side of a power convertor includes a sampling/tracking circuit and a comparator. The sampling/tracking circuit is coupled to the secondary side of the power convertor for generating a sampling value corresponding to an output voltage of the power convertor when a sampling signal is enabled, and generating a tracking value corresponding to the output voltage. The comparator is coupled to the sampling/tracking circuit for generating a warning signal to a primary-side regulation controller of the power converter according to the sampling value and the tracking value during an enabling period of a tracking signal. The primary-side regulation controller adjusts a frequency of a gate control signal according to the warning signal, and the sampling signal and the tracking signal are not enabled simultaneously.

Controller applied to a secondary side of a power convertor and operation method thereof

A voltage converter and a control circuit thereof are provided. The control circuit includes a voltage status comparator and a control signal generator. The voltage status comparator receives an input voltage and an output voltage, and provides a base voltage. The voltage status comparator compares voltage values of the output voltage and the input voltage or compares voltage values of the output voltage and the base voltage according to a voltage status of the input voltage, and generates a comparison result. The voltage status comparator generates a bias voltage according to the comparison result. The control signal generator generates a control signal according to the bias voltage and transmits the control signal to a control terminal of a driving switch, where the driving switch is turned on or cut off according to the control signal.

A power supply detects a falling rate of an output voltage for fast load-transient response. The power supply with a primary side and a secondary side isolated from each other comprises a primary-side control circuit and a secondary-side control circuit. The primary-side control circuit controls a power switch to convert an input power source on the primary side into an output power source on the secondary side. The output power source has the output voltage. The secondary-side control circuit detects the falling rate and sending information to the primary-side control circuit when the falling rate exceeds a predetermined rate. In response to the information, the primary-side control circuit starts anew switching cycle of the power switch.

Switching mode power supplies with fast load-transient response

Disclosed are LED controllers for dimming. An LED controller includes a current driver, a pulse-width modulator, a feedback circuit, and a decoupling circuit. The current driver, selectively in response to a dimming signal, causes a driving current flowing through one LED string. The dimming signal is capable of defining a dimming ON period and a dimming OFF period. The pulse-width modulator generates a PWM signal to control a power switch, in order to buildup a driving voltage at a power node of the LED string. The PWM signal is generated in response to a compensation signal. The feedback circuit, based upon a feedback voltage from the light emitting device, drives a compensation capacitor to generate the compensation signal. The decoupling circuit defines a decoupling period at the start of the dimming ON period and causes the feedback circuit not driving the capacitor during the decoupling period.

LED controllers for dimming at least one LED string

A ripple suppressor suppresses ripples of a channel current. The ripple suppressor comprises a voltage-controlled current source, a stabilizer, and an auto-calibration circuit. A control voltage at a control node controls the channel current flowing through a path connecting first and second channel nodes. The voltage-controlled current source receives a current-setting signal to generate the control voltage, so as to stabilize the channel current in response to the current-setting signal. The stabilizer at least provides low-pass filtering to generate and stabilize the current-setting signal in response to a first channel voltage at the first channel node. The auto-calibration circuit controls the stabilizer in response to the control voltage, so as to make the control voltage in compliance with a first predetermined condition.

Ripple suppressor

A control circuit suitable for a power supply. The power supply has a transformer with a primary winding and a secondary winding magnetically coupled to each other. The transformer is configured to transfer electric energy from a primary side to a secondary side and to build an output power source in the secondary side. The control circuit has a primary-side controller and a secondary-side controller. The primary-side controller is in the primary side, configured to control a current through the primary winding. In the secondary side, the secondary-side controller is powered by the output power source and configured to provide a command code with several command bits sequentially transmitted to the primary-side controller, so as to set an operation mode that the primary-side controller operates in.

Power supplies and control methods suitable for sequentially transmitting command bits from secondary side to primary side

The disclosure regards to drivers and driving methods for a LED string consisting of LEDs. The LED string and a current switch are coupled in series between a power line and a ground line. The power line is powered to regulate a signal representing a current passing through the LED string. An enable signal capable of switching the current switch is provided. Whether a predetermined event occurs is detected. When the predetermined event occurs, the enable signal is clamped to have a predetermined logic value, the current switch thereby being kept either open or short.

Drivers and driving methods for a LED string, capable of providing LED short protection or avoiding LED flickering

A controller for dimming light-emitting diodes includes a pulse width modulation pin, a low-pass filter, a frequency detection unit, and a control signal generation module. The low-pass filter generates a direct current signal according to a pulse width modulation signal generated by a micro-controller. The frequency detection unit generates a logic value according to a threshold and the pulse width modulation signal. The control signal generation module generates a switch control signal to a first switch connected to the light-emitting diodes in series according to the direct current signal, the logic value, a reference voltage, and the pulse width modulation signal. When a frequency of the pulse width modulation signal is lower than the threshold, the controller enters a digital dimming mode; and when the frequency of the pulse width modulation signal is higher than the threshold, the controller enters an analog dimming mode.

Controller and method for dimming light-emitting diodes

A short circuit detection circuit for detecting short circuit of a series of light-emitting diodes includes a constant current source, a rectifier, and a detector. The constant circuit source provides a setting current. The rectifier is coupled between a feedback node and the constant current source. The feedback node is coupled to a terminal of the series of light-emitting diodes. When a feedback voltage of the feedback node exceeds a short reference voltage, the rectifier allows the setting current sinks the feedback node. The detector detects the feedback voltage of the feedback node. When the feedback voltage exceeds a predetermined value, short-circuit protection is triggered to make the series of light-emitting diodes be turned off.

Growing community of inventors

Hsin-Chu, Taiwan

Ching-Tsan Lee