Abstract: This paper mainly focuses on Renesas' capacitive touch detection technology research, including the basic principles of touch-key detection and the noise immunity technology. The section of touch-key detection principles introduces the capacitance value - current conversion theory, the current digitalization and the touch-key ON/OFF determination. The section of noise immunity technology introduces the phase shifting technology and the spread spectrum technology implemented by hardware, as well as the software drift correction technology and the software smoothing technology.

Key words: Capacitive touch, Touch detection, Touch noise immunity