What is an inverter

An inverter is a DC to AC transformer, which is actually a process of voltage inversion with a converter.

The converter converts the AC voltage of the power grid into a stable 12V DC output, while the inverter converts the 12V DC voltage output by the adapter into high-frequency high-voltage AC power; Both parts also use the commonly used Pulse Width Modulation (PWM) technology. The core components are all PWM integrated controllers, with UC3842 as the adapter and TL5001 as the inverter. The working voltage range of TL5001 is 3.6-40V, and it is equipped with an error amplifier, a regulator, oscillator, PWM generator with dead zone control, low-voltage protection circuit, and short circuit protection circuit inside.

Input interface section: The input section has 3 signals, 12V DC input VIN, working enable voltage ENB, and panel current control signal DIM. The VIN is provided by the adapter, and the ENB voltage is provided by the MCU on the motherboard, with a value of 0 or 3V. When ENB=0, the inverter does not work, while when ENB=3V, the inverter is in a normal working state; The DIM voltage is provided by the motherboard, with a range of variation between 0 and 5V. Different DIM values are fed back to the feedback end of the PWM controller, and the current provided by the inverter to the load will also be different. The smaller the DIM value, the greater the output current of the inverter.

Voltage starting circuit: ENB is at high voltage level,

Output high voltage to light up the backlight tube of the panel.

PWM controller: It consists of 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 is composed of MOS switching tubes and energy storage inductors. The input pulse is amplified by a push-pull amplifier to drive the MOS tube to perform switching actions, allowing DC voltage to charge and discharge the inductor, so that the other end of the inductor can receive AC voltage.

LC oscillation and output circuit: Ensure the required voltage of 1600V for the start of the lamp, and reduce the voltage to 800V after the lamp starts.

Output voltage feedback: When the load is working, the feedback sampling voltage plays a role in stabilizing the voltage output of the inverter.