Richtek Technology Corporation

Ricktek Technology Corporation

Shei-Chie Yang

Shui-Mu Lin

Huan-Chien Yang

Pao-Hsun Yu

Yuan-Yen Mai

Chien-Chung Chen

Chueh-Kuei Jan

Chun-I Lin

Ming-Yu Lin

Chuan-Yo Hsiao

Hsan-Fong Lin

Shih Chung Wang

Jun-Sheng Cheng

Jian-Yu Tu

Cheng-Hung Hsu

A switching regulator includes a boost power stage circuit and a control circuit. The boost power stage circuit includes: at least one power switch configured to switch a terminal of an inductor according to an operation signal during a normal operation period, such that the terminal of the inductor is switched between an output voltage and ground level; and a power line switch connected in series to the inductor between the input voltage and the output voltage. The power line switch is turned OFF when the output voltage is short to ground level, to prevent a short current from flowing from input voltage to ground level. The control circuit generates the operation signal according to the output voltage and determines whether the power line switch is P-type or N-type MOS device, so as to turn OFF the power line switch when the output voltage is short to ground level.

Switching regulator and control circuit and control method thereof

A buck-boost switching regulator includes: a power switch circuit including an input switch unit and an output switch unit; a bypass control circuit configured to operably generate a bypass control signal according to a conversion voltage difference between an input voltage of an input power and an output voltage of an output power and according to whether an inductor current flowing through an inductor reaches an output current of the output power; and a bypass switch circuit, wherein when the conversion voltage difference is below a reference voltage and when the inductor current flowing through the inductor reaches the output current, the bypass control signal controls the bypass switch circuit to electrically connect the input power with the output power, so that the buck-boost switching regulator operates in a bypass mode.

Buck-boost switching regulator capable of damping out the ringing and control method thereof

A buck-boost switching regulator includes: a power switch circuit including an input switch unit and an output switch unit which switch a first terminal and a second terminal of an inductor for buck-boost conversion; at least one low dropout regulator correspondingly coupled to at least one output high side switch in the output switch unit to correspondingly convert at least one low dropout voltage into at least one output voltage; and a bypass control circuit configured to operably generate a bypass control signal according to a conversion voltage difference between the input voltage and the corresponding low dropout voltage; wherein when the corresponding conversion voltage difference is lower than a reference voltage, the bypass control signal controls a corresponding bypass switch to electrically connect the input voltage with the corresponding low dropout node.

Buck-boost switching regulator having bypass mode and control method thereof

A method for brightness control, adapted to a light emitting device emitting a light of an output brightness, comprises: setting the output brightness to be an initial value, and controlling the light emitting device emitting the light accordingly; setting a target value, and controlling the output brightness changing from the initial value toward the target value with the brightness changing rate of the brightness zone corresponding to the initial value; controlling the output brightness changing toward the target value with the following brightness changing rate when the output brightness crossing one of the brightness thresholds and entering the following brightness zone, wherein the following brightness changing rate corresponds to the following brightness zone; stopping changing the output brightness when reaching the target value.

Method for brightness control

An LED driver includes a power converter to convert an input voltage to a regulated voltage, a current source to be connected with an LED string in series between the power converter and a bias node, and a switching circuit to apply a bias voltage to the bias node to set the total voltage drop of the LED string and the current source. By controlling the total voltage drop of the LED string and the current source, the LED driver will automatically select a boost mode or a buck mode for operation, thereby improving the efficiency thereof.

LED driver and driving method

LED dimming control circuit and method compensate LED current or LED average current by LED characteristics to improve dimming efficiency and performance. LED characteristic related look-up tables are stored to provide compensation values, and input LED current setting information is compensated by the compensation values to generate corrected LED current setting information for determining LED brightness.

Compensating LED current by LED characteristics for LED dimming control

The present invention discloses an LED controller with de-flicker function and an LED de-flicker circuit and method thereof. The LED controller includes: a duty ratio calculation circuit for receiving a pulse width modulation (PWM) signal and generating a duty input signal, indicating a digital duty ratio of the PWM signal; an LED de-flicker circuit for receiving the duty input signal and generating a duty output signal wherein a noise in the duty input signal is filtered; and a dimming circuit for receiving the duty output signal and generating a dimming signal to control an LED circuit; wherein the duty output signal remains unchanged when the variation of the duty input signal is not larger than a hysteresis threshold, and the duty output signal follows the duty input signal when the variation of the duty input signal is larger than the hysteresis threshold.

LED controller with de-flicker function and LED de-flicker circuit and method thereof

A driving system and method for electroluminescent displays which by connecting the electroluminescent elements that have been lighted up to the electroluminescent elements that are to be lighted up causes charge to be shared among the elements, so as to increase the voltage level at the anodes of the electroluminescent elements which are to be lighted up, thereby reducing the power consumption and increasing the response speed.

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Wur, Taiwan

Shei-Chie Yang