Generation of a VCOM buffer input using PWM signal
In an LCD, the backlight shines through the liquid crystal material and the voltage across the liquid crystal controls how much light shines through it. An active matrix LCD (AMLCD) contains many pixels arranged in a grid pattern. The voltage across each pixel is controlled individually so that high resolution images can be created. One terminal of every pixel is connected to a common plane. The voltage on this plane is called the VCOM voltage and it is the reference voltage for each pixel. The VCOM voltage is typically adjusted for best image quality during production and is often generated by a digital-to-analog converter (DAC), such as the LM8342 device, buffered by an amplifier.