Novatek Microelectronics Corp.

Tsung-Hau Chang

Chin-Hsun Hsu

Kuo-Ching Hsu

Ting-Wei Liao

Wen-Hsin Cheng

Hsing-Chien Yang

Lan-Ting Hsu

Ying-Hao Hsu

Feng-Wei Chien

Chia-Hung Lin

Kuang-Feng Sung

Yung-Cheng Lin

Jr-Ching Lin

Ying-Hsiang Wang

Chia-Lin Chiu

Jung-Hsing Liao

Ping Chen

Yung-Chou Lin

Chi-Wei Liu

An operational amplifier includes a first differential input pair, a first switch and a second switch. The first differential input pair includes a first input transistor and a second input transistor. The first input transistor has a gate terminal coupled to an output terminal of the operational amplifier. The second input transistor has a gate terminal. The first switch is coupled between the gate terminal of the first input transistor and the gate terminal of the second input transistor. The second switch is coupled between a first input terminal of the operational amplifier and the gate terminal of the second input transistor.

Capacitance decreasing scheme for operational amplifier

A driving circuit of display apparatus includes an operational amplifier (OP), comprising a plurality of input terminals; a digital-to-analog converter (DAC); a multiplexer, coupled to the OP and the DAC, comprising a plurality of switches; and a boosting module, configured to decrease an equivalent time constant between the DAC and the OP to increase an output slew rate of the OP in a boosting period; wherein the boosting period is enabled before a steady state of the OP.

Driving circuit of display apparatus and driving method thereof

A driving method of a light-emitting diode (LED) adapted to a driving apparatus is provided. The driving method includes detecting whether the driving apparatus performs dimming, and if the driving apparatus performs dimming, determining whether a predetermined requirement for dimming control is met or not. When the predetermined requirement for dimming control is not met, respective current magnitudes of a plurality of driving currents are regulated, and each of the driving currents is output for a full time of a period. Conversely, when the predetermined requirement for dimming control is met, each of the driving currents is output for a partial time of a period.

Driving apparatus of light emitting diode and driving method thereof

A light-emitting diode (LED) driving circuit includes an LED control circuit and a power stage circuit. The LED control circuit shifts an input pulse width modulation (PWM) signal toward a higher frequency direction in a frequency domain to generate an output PWM signal having a duty cycle substantially the same as a duty cycle of the input PWM signal. The power stage circuit outputs an LED driving current according to the output PWM signal.

LED device, LED driving circuit and method

Provided is a light emitting diode (LED) driving circuit for driving a plurality of LED groups. The LED driving circuit includes: a voltage converter, for converting an input voltage into an output voltage, the output voltage coupled to a respective first terminal of each of the LED groups; and a controller, coupled to the voltage converter for controlling the voltage converter, the controller including a plurality of output channel terminals respectively corresponding to a plurality of output channels, one or more of the output channels are enabled and one or more of the output channels are disabled. One or more of the output channel terminals corresponding to the one or more enabled output channels are coupled to second terminals of corresponding ones of the LED groups, and one or more of the output channel terminals corresponding to the one or more disabled output channels are coupled to a reference voltage.

Driving circuit and method for driving current-driven devices and electronic device applying the same

A circuit for generating reference voltage and reference current includes a band-gap reference circuit and a voltage-to-current converting circuit. The band-gap reference circuit is configured to generate a temperature-independent reference voltage by generating a first current with a positive temperature coefficient. The voltage-to-current converting circuit is coupled to a node of the band-gap reference circuit and configured to convert a voltage with a negative temperature coefficient at the node into a second current with a negative temperature coefficient. The band-gap reference circuit and the voltage-to-current converting circuit share a common current source having a feedback transistor through which a reference current flows. The reference current is divided into the first current of the band-gap reference circuit and the second current of the voltage-to-current converting circuit, thus having a temperature coefficient substantially equal to zero by combining the first current and the second current.

Circuit and method for generating reference voltage and reference current

A light-emitting diode (LED) device for preventing soft-start flicker includes an LED module, a voltage converter, a variable current load and a loop control unit. The loop control unit is coupled to the LED module, the voltage converter and the variable current load, and includes a soft-start unit and a dimming control unit. The soft-start unit is utilized for activating a soft-start mechanism of the voltage converter when power of the LED device is turned on. The dimming control unit is utilized for controlling the variable current load to progressively increase a load current of the LED module to a target value and to maintain the load current on the target value until the soft-start mechanism is completed, so as to perform dimming control on the LED module.

LED device and method for preventing soft-start flicker

A light emitting diode (LED) driving apparatus is disclosed. The LED driving apparatus includes a power converter, a voltage sample-and-hold and comparison circuit, and a pre-charge clock generator. The power converter has a power transistor switch for processing power conversion and outputs a driving voltage at an output terminal. The voltage sample-and-hold and comparison circuit enters a sample-and-hold mode or a comparing mode according to a dimming status signal. The voltage sample-and-hold and comparison circuit samples and holds a feedback voltage to obtain a pre-storage voltage during the sample-and-hold mode and compares the pre-storage voltage with the feedback voltage to obtain a comparison result during the comparing mode. The voltage sample-and-hold and comparison circuit generates a pre-charge enable signal according to the comparison result. The pre-charge clock generator generates a pre-charge clock signal to control the power transistor switch according to the pre-charge enable signal and a clock signal.

Light emitting diode driving apparatus and method for holding driving voltage thereof

The present invention provides a current driver for driving a current driven device. The current driver includes a driving circuit, configured to generate a driving current to drive the current driven device, and conduct or cut off a driving current path through which the driving current flows according to a voltage level of a driving control node, and an accelerating circuit, coupled to the driving control node of the driving circuit, configured to provide an accelerating current flowing through the driving control node to accelerate a voltage level transition at the driving control node during an activation period of the driving circuit, and automatically cut off the accelerating current when a voltage level of the driving control node reaches a specific level.

Current driver, electronic device and current driving method

A frequency generator is used for generating a frequency within a frequency range. The frequency generator includes a variable current source, a voltage drop generation unit, a voltage source, a detection unit, a conversion unit, and an oscillating circuit. The variable current source is used for outputting a current according to a control signal. The voltage drop generation unit is used for generating a voltage drop according to the current. The voltage source is used for outputting a voltage range. The detection unit is used for outputting the control signal to the variable current source according to a relationship between the voltage drop and the voltage range. The conversion unit is used for outputting a digital code according to the relationship between the voltage drop and the voltage range. The oscillator circuit is used for generating the frequency according to the digital code.

Frequency generator

An LED device with simultaneous open and short detection function includes a plurality of LED strings, a voltage converter, a current driving unit, a loop control unit, an open detector, a short detector and a voltage detector. The open detector and the short detector are utilized for detecting LED open and LED short for the plurality of LED strings, respectively. The voltage detector is coupled to the open detector, the short detector and the voltage converter, and is utilized for generating a reset signal to the short detector according to an output voltage of the voltage converter when the LED open occurs on the plurality of LED strings, so as to initiate the LED short detection for the plurality of LED strings again.

LED device with simultaneous open and short detection function and method thereof

A driving method of a light-emitting diode (LED) adapted to a driving apparatus is provided. The driving method includes receiving a dimming signal, detecting whether the driving apparatus performs dimming, and if the driving apparatus performs dimming, determining whether a duty cycle of the dimming signal is smaller than a predetermined value. When the duty cycle of the dimming signal is not smaller than the predetermined value, respective current magnitudes of a plurality of driving currents are regulated according to the dimming signal, and each of the driving currents is output for a full time of a period. Conversely, when the duty cycle of the dimming signal is smaller than the predetermined value, each of the driving currents is output for a partial time of a period. A driving apparatus employing the driving method is also provided.

A light source apparatus and a light source driving circuit are provided. The light source driving circuit includes an operation amplifier (OP-AMP), a transistor, and a switch unit. A first input terminal and an output terminal of the OP-AMP couple to a predetermined voltage and a control terminal of the transistor, respectively. A first terminal of the transistor couples to a light source. The switch unit includes a first signal terminal receiving a first voltage greater than a predetermined voltage, a second signal terminal coupled to a second input terminal of the OP-AMP, a third signal terminal coupled to a second terminal of the transistor, and an enabling terminal receiving a driving voltage. A voltage of the third signal terminal or a voltage of the first signal terminal is determined to transmit to the second signal terminal in accordance with the driving voltage.

Growing community of inventors

Hsinchu, Taiwan

Tsung-Hau Chang