Fairchild Korea Semiconductor Ltd.

Eunchul Kang

Juho Kim

Duckki Kwon

Kyoungmin Lee

Byongsung Lee

A low-voltage and over-voltage detection circuit receives a power source voltage, generates a shift voltage by shifting the received voltage to a predetermined level, and fixes the shift voltage as a clamping voltage when the shift voltage is higher than a predetermined clamping voltage. The low-voltage and over-voltage detection circuit includes a first transistor and a second transistor. The first transistor generates a regulator voltage that varies according to the power source voltage and performs a switching operation according to the shift voltage and the regulator voltage, and the second transistor is connected in parallel with the first transistor and generates hysteresis. The low-voltage and over-voltage detection circuit determines whether the power source voltage is a low-voltage or an over-voltage by using a drain voltage generated according to currents flowing to the first and second transistors.

Under-voltage and over-voltage detection circuit and driving method thereof

The present invention relates to a control device of a light emitting device that includes a plurality of LED rows formed of a plurality of LEDs sequentially connected in series. The control device includes: a plurality of switches respectively connected to the plurality of LED rows and sequentially transmitting a detection voltage of each of the plurality of LED rows, wherein the detection voltage corresponds to an output voltage applied to the plurality of LED rows; a comparator receiving the plurality of detection voltages, and generating a clock control signal according to a result of comparison with a predetermined reference; a clock signal generator generating a clock signal having a period that is changed according to the clock control signal; and a shift register that controls switching operations of the plurality of switches according to the clock signal.

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Seoul, South Korea

Eunchul Kang