How to suppress interference in the touch module of HMI (Human Machine Delivery)?

Interference suppression for HMI touch modules requires addressing three aspects: power integrity, signal integrity, and shielding protection. First, ensure a clean power supply to the touch module. Use a π-type filter circuit at the power input, such as a combination of a PBZ1608E102Z0T ferrite bead and X7R capacitors, to filter out high-frequency noise on the power lines. For touch signal lines, use twisted-pair or shielded routing and minimize trace length. Connecting small-value resistors (e.g., 22Ω-100Ω) in series on the signal lines effectively suppresses ringing and reflection. Simultaneously, connect ESD protection devices (e.g., ESD5V0D3B) in parallel with ground on the signal lines to absorb electrostatic discharge and fast pulse interference.

For capacitive touchscreens, the high frequency of their drive signals makes them susceptible to radiated interference; place decoupling capacitors (e.g., 0.1μF ceramic capacitors) near the power pins of the driver chip. Furthermore, the connection cable between the touch module and the motherboard is a critical path for interference coupling; use shielded cables with the shield properly grounded at both ends. If the touch module itself has a metal frame, ensure it is properly bonded to the system chassis to form a continuous shield. By taking the above comprehensive measures, the anti-interference capability and reliability of the touch module can be significantly improved.