Richtek Technology Corporation

Richtek Technology Corporation, R.o.c

Dialog Semiconductor (uk) Limited

Ricktek Technology Corporation

Pei-Cheng Huang

Jwin-Yen Guo

Jing-Meng Liu

Kuo-Chi Liu

Wei-Hsu Chang

Kuo-Chung Lee

Jo-Yu Wang

Fu-Sheng Tsai

Alan Somerville

Yen-Shin Lai

Roland Van Roy

Shao-Ming Sun

Shiue-Shr Jiang

Hung-Dar Wang

Yu-Kuang Wu

Jen-Hung Chi

Haó-Yu Chang

Ching-Jung Tseng

Chang-Chih Lin

Chih-Chang Chen

Ming-Hsueh Lee

Shih-Hua Chien

Chao-Hua Wu

A power management circuit is provided with groups of switches and a single shared inductor and is selectively configured in a first mode to act as a buck regulator and a second mode to act as a buck-boost regulator. There is a two-stage circuit topology, where both charging and regular operation of the device can be optimized. There is a switching charger integrated circuit that can be dedicated to performing a charging function, and there is a DC-DC power management integrated circuit that can be dedicated to regulating the system voltage provided by the battery while the battery is discharging.

Power management circuit

A method and apparatus for dynamically adjusting a dead time of a BLDC motor during a phase change detect the winding current of the BLDC motor during the dead time, and terminate the dead time when the winding current is detected to be substantially or close to zero. Thus, the method and apparatus can optimize the dead time and switch the BLDC motor between two phases at a zero-current point, without reducing the maximum rotation speed of the BLDC motor.

Method and apparatus for dynamically adjusting a dead time of brushless direct current motor during a phase change

The present invention discloses a direct current (DC) light emitting device control circuit with dimming function, and a method thereof, wherein the dimming function is provided in a feedback loop for feeding back a feedback signal from an output terminal to a power switch control circuit; the feedback signal relates to an output current supplied to the DC light emitting device. The present invention adjusts the feedback signal according to the desired brightness of the DC light emitting device. The present invention controls a power switch according to the adjusted feedback signal, such that the output current supplied to the DC light emitting device is adjusted, and accordingly the brightness of the DC light emitting device is adjusted below the full brightness.

Direct current light emitting device control circuit with dimming function and method thereof

An electrostatic transducer loudspeaker includes a filterless class-D amplifier to modulate an audio input signal to generate a modulated signal containing a PWM switching carrier component, and a transformer directly connected at an output side of the filterless class-D amplifier and directly connected at an input side of an electrostatic transducer, whereby the equivalent capacitance of the electrostatic transducer and the equivalent inductance of the transformer establish a resonance circuit to demodulate the modulated signal to generate an AC voltage to drive the electrostatic transducer.

Electrostatic transducer loudspeaker

A driving circuit for a sound outputting apparatus includes a H-bridge and a charge pump established by six switches for driving two types of loudspeakers, respectively. The six switches include two common switches to be configured in the H-bridge and the charge pump, thereby reducing the costs and circuit area of the driving circuit.

Driving circuit for a sound outputting apparatus

The present invention discloses a light emitting device control method for adjusting the brightness of the light emitting device by an AC signal, comprising: receiving a signal having a turn ON angle and converting the signal to a DC signal; obtaining an average of the DC signal level, the average being a function of the turn ON angle; determining a reference voltage of a current source circuit according to the average of the DC signal level; and controlling a current flow through the light emitting device by the current source circuit.

LED bulb, light emitting device control method, and light emitting device controller circuit with dimming function adjustable by AC signal

A zero-crossing detection circuit and a commutation device using the zero-crossing detection circuit are provided. The zero-crossing detection circuit is adapted into a three-phase brushless DC (direct current) motor with first to third coils. One terminal of each of the first to third coils is electrically coupled together with each other. The detection circuit comprises a first selection circuit, a second selection circuit and a comparator. The first selection circuit and the second selection circuit are both electrically coupled to another terminals of the first to third coils, to obtain first to third terminal voltages, and output one of the first to third terminal voltages according to a selection signal. The comparator is configured for comparing an output of the first selection circuit and an output of the second selection circuit, to output a comparing result.

Zero-crossing detection circuit and commutation device using the zero-crossing detection circuit

The present invention discloses a light emitting device open/short detection circuit, which is used for detecting at least one light emitting device string open/short. Each light emitting device string has a first end and a second end, wherein the first end is coupled to a voltage supply circuit to supply electrical power to the light emitting devices. The open/short detection circuit includes: an abnormal voltage detection circuit coupled to the light emitting device strings for receiving voltages of the second ends respectively and generating an abnormal voltage detection signal; a voltage setting circuit coupled to the abnormal voltage detection circuit for setting an abnormal reference level; and a determination circuit coupled to the voltage setting circuit. When the abnormal voltage detection signal is equal to or over the abnormal reference level, the determination circuit generates an open/short detection signal for an abnormal condition detected.

Light emitting device open/short detection circuit

By monitoring the temperature of an LED and the temperature of a controller chip for the LED, a thermal foldback control is employed to gradually decrease the driving current of the LED before the LED or the controller chip is over heated, so as to prevent an over temperature protection from being triggered to shutdown the controller chip to cause the LED to undesirably flicker.

Thermal foldback control for a light-emitting diode

The present invention discloses a light emitting device driver circuit and a method for driving a light emitting device. In the present invention, the secondary windings of a transformer provide positive and negative secondary voltages, so as to generate positive and negative output voltages. A light emitting device circuit is coupled between the positive and negative output voltages. As such, the specification to withstand high voltage for a device in the circuit is reduced.

Light emitting device driver circuit driving light emitting device by positive and negative voltages and method for driving light emitting device by positive and negative voltages

A class-D amplifier includes a ramp generator to provide a ramp signal having a frequency varying with an audio input signal, and a modulator to convert the audio input signal to a pulse width modulation signal according to the ramp signal for a driver to drive a load device. The varying frequency of the ramp signal will cause the frequency of the pulse width modulation signal unfixed and consequently improves EMI issue.

Variable frequency class-D amplifier, control method thereof, and ramp generator therefor

The present invention discloses a driver circuit for an electrostatic loudspeaker, comprising: a digital modulation encoder for receiving a digital audio signal and a fixed frequency pulse signal, and mixing them by modulation; a digital to analog converter for converting the output of the digital modulation encoder to an analog signal; a transformer for adjusting the voltage amplitude of the analog signal; and a demodulator for demodulating the adjusted analog signal to driver a speaker.

Driver circuit and driving method for electrostatic loudspeaker

For minimum pulse generation in a class-D amplifier, a trapezoid switching waveform shape is used to replace the tradition triangle type to generate PWM pulses. Two voltages are compared with a sawtooth wave signal to generate the trapezoid waveform signal and a constant pulse width signal. An audio input signal is compared with the trapezoid waveform signal to generate a pulse width modulation signal, and either the pulse width modulation signal or the constant pulse width signal is used for driving a load at an output of the class-D amplifier. Flexible minimum pulse width could be obtained by offsetting one of the two voltages in generation of the constant pulse width signal.

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Taipei, Taiwan

Pei-Cheng Huang