The output voltage of Haier LE48F3000W backlight boost board is 12V/5V.

The LCD high-voltage board, also known as the boost board, is an important part of the LCD system and is responsible for providing a high enough input voltage to make the LCD screen glow. It can be said that the high-voltage board is a controllable inverter circuit.

The circuit of the liquid crystal high-voltage board consists of a pulse width generating IC (including peripheral circuits such as oscillation/control/feedback), power supply control circuit, self-oscillation generator, feedback sampling circuit, etc. The pulse width generation IC is mainly responsible for generating a rectangular pulse signal, which changes with the modulation of the brightness, and is used to adjust the power supply from 12V to the self-oscillator to generate a high voltage that varies with the power supply for the lamp to emit light. Its periphery consists of an oscillation circuit and so on. The power supply control circuit is generally composed of several transistors. Depending on the presence or absence of the control voltage of the main board, the power supply of the pulse width IC is turned on or off to achieve the purpose of controlling the entire booster board. The self-excited oscillation generator mainly generates the high voltage required by the lamp. When voltage is added to it, it can self-oscillate and generate inverter high voltage (i.e. inverter). The added voltage is 12V modulated by the pulse width IC (generally the modulated input is between 9~12V). The feedback sampling circuit mainly collects the self-excited output and the voltage and current of the lamp secondary (low-voltage line), and feeds it back to the pulse width IC to stabilize or cut off its pulse width output. We see it every day and it turns on and off. , that is, the feedback circuit works, resulting in no pulse width output