How to improve the interference immunity of touch chips in HMI (Human Machine Interface) systems?

Improving the anti-interference capability of HMI touch chips requires a two-pronged approach: hardware enclosure and software algorithms. On the hardware side, provide a "quiet island" for the touch chip: use a dedicated LDO to power its analog and digital sections, and connect a ferrite bead (e.g., PBZ1005E102Z0T) in series at the power input, along with MLCC capacitors of various capacitances in parallel for fine filtering. RC filters or small ferrite beads can be added to critical control signal lines such as reset and interrupt of the touch chip. The input pins of the sensing channel are weak points; in addition to conventional ESD protection diodes, a small filter resistor can be connected in series and a capacitor to ground in parallel to form a low-pass filter, but care must be taken not to affect the touch detection response speed.

Place the touch chip in a quiet area of the PCB, completely cover it with a ground plane, and surround it with an array of ground vias. On the software side, employ advanced digital filtering algorithms, such as adaptive baseline tracking, frequency hopping to avoid fixed-frequency interference, and multiple sampling for median value. Optimize touch detection parameters, such as scanning frequency, sensitivity, and threshold, to achieve the best signal-to-noise ratio in noisy environments. By constructing a hardware barrier using filtering and protection devices from Audiotech, and supplementing it with robust firmware algorithms, the robustness and reliability of touch chips in complex electromagnetic environments can be significantly improved.