Fairchild Korea Semiconductor Ltd.

Shanmei Li

Jin-Tae Kim

Hojae Lee

Gwan-Bon Koo

Hyun-Chul Eom

Byunghak Ahn

Kwang-Il Lee

Dong Jin Park

Gyoung-Soo Park

Jin Chenghao

Jongmu Lee

Disclosed are an LED emitting device and driving method thereof. The LED emitting device controls an LED drive switch connected to a first end of an LED string to control an output current supplied to the LED string. The LED emitting device generates feedback information on the output voltage or the output current supplied to the LED string, and uses the output current to sense an open lamp state of the LED string. The LED emitting device uses a voltage at a first end of the LED drive switch to sense a change of the LED string to a normal state from the open lamp state.

LED emitting device and driving method thereof

In a converter using a transformer, a switch controller controlling a main switch and an auxiliary switch increase a turn-on time of the auxiliary switch when a voltage of a signal corresponding to a current flowing to a primary coil of the transformer is greater than a reference voltage for a predetermined period.

Switch controller and converter including the same for prevention of damage

The present invention relates to a hold-up time expansion circuit and a converter including the same. The hold-up time expansion circuit controls switching frequency of at least one switch according to the input voltage of the converter. The converter is dependent on the switching frequency that is controlled by the hold-up time expansion circuit, and controls the duty of at least one switch according to the feedback signal of the output voltage.

Hold-up time extending circuit and converter including the same

A converter is provided including: a first switch; an energy transmitting element for converting input energy into output energy according to the switching of the first switch; and a switching controller for detecting a time when a voltage between a first terminal and a second terminal of the first switch reaches a valley of a resonance waveform, and actuating the first switch corresponding to one of the detected valleys of the resonance waveform. The switching controller includes: a valley detector for changing the state of the output signal whenever a voltage between a first terminal and a second terminal of the first switch reaches a valley of the resonance waveform; and a PWM controller for actuating the first switch corresponding to an output signal of the valley detector.

Converter that actuates a switch corresponding to a detected valley of a resonance waveform

Growing community of inventors

Bucheon, South Korea

Shanmei Li