How does the inverter work?

Input interface part: the input part has three signals, namely 12V DC input VIN, working enable voltage ENB and panel current control signal DIM. The VIN is provided by the adapter, and the voltage of the ENB is provided by the MCU on the motherboard, and its value is 0 or 3V. When ENB=0, the inverter does not work, and when ENB=3V, the inverter is in a normal working state. DIM voltage is provided by the motherboard, ranging from 0 to 0~5V. When different DIM values are fed back to the feedback terminal of PWM controller, the current provided by inverter to the load will be different. The smaller the DIM value, the greater the current output by the inverter.

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Voltage start-up loop: when the ENB is at high level, it outputs high voltage to light the backlight lamp of the panel.

PWM controller: It has the following functions: internal reference voltage, error amplifier, oscillator and PWM, overvoltage protection, undervoltage protection, short circuit protection and output transistor.

DC conversion: A voltage conversion circuit consisting of MOS switch and energy storage inductor. The input pulse is amplified by the push-pull amplifier and drives the MOS transistor switch, so that the DC voltage charges and discharges the inductor, and the other end of the inductor gets the AC voltage.

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LC oscillation and output circuit: ensure the voltage of 1600V required for lamp startup, and the voltage will drop to 800V after lamp startup.

Output voltage feedback: when the load is working, feedback the sampling voltage to stabilize the voltage output of I inverter.

Inverter is a DC-to-AC transformer, which is actually a voltage inverter process and converter. The converter converts the AC voltage of the commercial power grid into a stable 12V DC output, and the inverter converts the 12V DC voltage output by the adapter into high-frequency and high-voltage AC. The pulse width modulation (PWM) technology widely used at present is also adopted in both parts. Its core part is a PWM integrated controller, the adapter uses UC3842, and the inverter uses TL500 1 chip. The working voltage range of TL500 1 is 3.6~40V, and it is equipped with error amplifier, voltage regulator, oscillator, PWM generator with dead-time control, low-voltage protection circuit and short-circuit protection circuit.

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