Introduction

Hello! Everyone! I am Nuvoton FAE Tim. Today, I will show you ML56 Capacitive Touch Key Technology. First introduce the Capacitive Touch Key Fundamentals. The capacitance of the sensor without a finger touch is called as “parasitic capacitance”, CP. Parasitic capacitance results from the electric field between the sensor (including the sensor pad and traces) and other conductors in the system such as the ground planes, traces, any metal in the product’s chassis or enclosure, etc. The capacitance between the sensor pad and the finger is CF. The total capacitance CT of the sensor is the sum of CP and CF. Next, we will explain the ML56 Capacitive Touch Key Sensing Method. ML56 implements two switching capacitor banks for injecting charges to CP (or CT) and CR. CR is the parasitic capacitance of reference channel. After touch key calibration, CP and CR are balanced with CB and CCB (comparator output is “low”). Touch the sensing touch key which makes CT = CP + CF Now the negative input terminal voltage of the comparator is lower than positive side and comparator output is “high”. ML56 touch key controller will increase CCB to CCB’ to balance CT and CR again (comparator output is “low”). A finger touch can be detected by checking the difference of CCB and CCB’. By comparing the CCB’ shift level from CCB, the steady state to a predetermined threshold, the algorithm can determine whether the touch key is in ON (Touch) or OFF (No Touch) state. That's all for today's video, thank you everyone! If you have any questions, please contact us. - For more information, please visit Nuvoton Technology Website: https://bit.ly/3hVdcmC Buy now: https://direct.nuvoton.com/tw/low-power-8051-series/ Contact us: SalesSupport@nuvoton.comon.com #Product #Learning #Basic #en

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