Fairchild Korea Semiconductor Ltd.

Samsung Sdi Co., Inc.

Yonsei University

System General Corporation

Jin-Hwa Chung

Chan Son

Ta-Yung Yang

Jin-ho Kim

Sang-Kyun Kang

Kyoung-Hwan Choi

Jae-Soon Choi

Hak-Hee Lee

Byung-hak Ahn

Jaewoon Kim

Chun-Chi Chen

Iiyong Jung

Soon-ho Song

The present invention provides a control circuit for LED driver. A voltage-feedback circuit is coupled to LEDs to sense a voltage-feedback signal for generating a voltage loop signal. Current sources are coupled to the LEDs to control LED currents. A detection circuit is connected to sense voltages of current sources for generating a current-source loop signal in response to a minimum voltage of the current sources. Furthermore, a buffer circuit generates a feedback signal in accordance with the voltage loop signal and the current-source loop signal. The feedback signal is coupled to limit a maximum voltage of the LEDs and regulate the minimum voltage across the current sources.

High efficiency LED driver with current source regulations

The present invention relates to an LED light emitting device and a driving method, and discloses a technology that may improve a slew rate of a channel current flowing through an LED channel when driving with a pulse width modulation method. For this, the present invention includes an LED channel consisting of a plurality of LED elements that are consecutively and serially connected, a current control switch that is connected to the end of the LED channel and performs a switching operation, and an operational amplifier that controls the switching operation of the current control switch according to a pulse width modulation signal. The LED driver samples an output voltage at the operational amplifier when the pulse width modulation signal is in an on state, and maintains the output voltage of the operational amplifier when the pulse width modulation signal is in an off state.

LED light emitting device and driving method thereof

A method of measuring methanol vapor concentration on a real-time basis and a methanol vapor concentration measuring apparatus used in fuel cells. The method of measuring methanol vapor concentration involves using an absorption spectrometry technique, that is, after measuring intensities Iand Iof light of a laser before and after passing through a space filled with methanol vapor and into which light is irradiated, the methanol vapor concentration is calculated by substituting the intensities Iand Iinto an equation defined as I/I=exp (K&#xb7;L&#xb7;C), where K represents the absorption coefficient, L represents the length of the space through which the laser passes, and C represents the methanol vapor concentration.

Method and apparatus for measuring methanol vapor concentration, method of controlling methanol vapor concentration in a fuel cell, and fuel cell using the same

A load driver includes an inverter and an inverter driver. The inverter converts an input voltage into a driving voltage of a discharge lamp using at least one first switch for switching according to a duty ratio, and the inverter driver controls the inverter. The inverter driver controls the duty ratio using a voltage of a capacitor and a control signal having a waveform that is repeated with a predetermined frequency. The capacitor is charged and discharged by a current corresponding to a difference between a feedback voltage corresponding to a current flow to the discharge lamp and a reference voltage. Such inverter driver controls to gradually increase the output voltage of the inverter in the soft start period by setting the voltage of the capacitor as a voltage corresponding to the control signal.

Inverter driver and load driver including the same, and driving method thereof

Growing community of inventors

Seoul, South Korea

Jin-Hwa Chung