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Cap-Sense PCB Hardware Design - Schematics

Looking at the schematics of the IS31SE5117 evaluation board, the engineer wants to make few observations: First, IS31SE5117 comes in QFN-24 package, but the underlying MCU, IS31CS8974, is available also in TSSOP-24 package. Second, the traces to the Cap-sense electrodes need to be short and include a serial resistor. Also, an option to add small capacitor to ground for better filtering is advised too. Third, the I2C (or SPI) interface to host is needed especially for easy calibration of the sensors, and also allow re-programing of the device if it is ever needed. Finally, the device can be powered from either external power supply or through the I2C interface.