How to filter out display driver interference in HMI (Human Machine Interface) systems?

To filter interference from the HMI display driver circuit, noise control needs to be implemented at three input points: power supply, signal, and clock. Display driver chips, whether timing controllers on the T-Con board or source driver chips, operate at high frequencies and consume significant power. First, their power supply must be adequately filtered using a multi-stage decoupling strategy: a power bead, such as the PBZ2012E102Z0T, is used at the power input to form the first stage of filtering with an electrolytic capacitor; 0.1μF and 1μF MLCC capacitors are placed next to each power pin of each driver chip. For high-speed differential input signals such as LVDS or eDP, a common-mode choke, such as the CMZ2012A-900T, can be connected in parallel near the receiver to suppress common-mode noise.

The pixel clock and horizontal/vertical sync signals generated by the driver chip are potential sources of radiation; small resistors can be connected in series on these signal lines. For the source drive signal (analog voltage) output to the LCD panel, its reference voltage VCOM must be extremely stable and should be generated using a dedicated low-noise LDO with enhanced filtering. The display driver circuit is placed in a separate area of the PCB and isolated from other circuits using grounded copper foil or a shield. By employing ferrite beads, common-mode chokes, and low-ESL capacitors from Audiotech Electronics for targeted filtering and isolation, interference generated by the display driver circuit can be effectively filtered out, ensuring a clear and stable display image.