O2micro International Limited

02 Micro International Limited

02micro Inc.

Footshen Wong

Vlad Mihail Popescu-Stanesti

Chun-Hsi Lin

Mingkwang Han

Winson Wong

Laszlo Lipcsei

Sheng Huang

Chen-Hsiang Yu

Chien Kung

Vlad Popescu-Stenesti

Mingkwong Han

Xiachua Hou

ChunHsi Lin

Jacky Lin

The present invention is an apparatus for driving white LEDs. The apparatus includes a switchable current sink, a DC-DC converter and a reference circuit. The DC-DC converter provides a driving voltage to a plurality of LEDs. The switchable current sink regulates currents through the plurality of LEDs, and the switchable current sink further provides a first reference voltage and outputs a plurality of voltage drops. The reference circuit receives the first reference voltage and the plurality of voltage drops to provide a second reference voltage to the DC-DC converter. The DC-DC converter adjusts the driving voltage provided to the plurality of LEDs according to the second reference voltage. In this way, the driving voltage is regulated to a minimum possible value and consequently the voltage drops across the switchable current sink is minimized. Hence, the LED driving system maintains higher efficiency.

Apparatus and method for regulating white LEDs

A power supply topology with pulse width modulation frequency control allows the use of an inductor with higher inductance in a converter. By controlling the switching frequency of the pulse width modulation signal, the inductor can achieve high efficiency during a light load condition and is also suitable for a heavy load condition.

Power supply topologies with PWM frequency control

A DC-to-DC converter with improved transient response, accuracy and stability is disclosed. The DC-to-DC converter includes a comparator, a driver, at least one switch and a stability circuit. The stability circuit receives a voltage signal based upon sensing one of the at least one switch. The configuration with elimination a current sensing resistor can create a simpler solution for the DC-to-DC converter.

DC-to-DC converter with improved transient response

A method for using a single pin to support both power input and power control functions for an integrated circuit, wherein the integrated circuit is in communication with a system. The method includes receiving at the pin a power input signal from the system, generating a power control signal based on the power input signal through a control signal generating circuit, and sending the power control signal to the integrated circuit.

Single pin for multiple functional control purposes

A circuit according to the present invention is used for driving a photoflash diode and comprises a current sink, a feedback circuit, and a DC-DC converter. The current sink is coupled to the photoflash diode for controlling the current through the photoflash diode. The feedback circuit receives a feedback signal indicative of the electrical condition of said first current regulator. The DC-DC converter is coupled to an external power source and the feedback circuit for powering the photoflash diode so as to control the electrical condition of the current sink to a predetermined value.

Highly efficient driving of photoflash diodes using low and fixed voltage drop-out current sink

Growing community of inventors

Singapore, Singapore

Footshen Wong