Hello! Everyone! I am Nuvoton FAE Tim. Today, I will show you ML56 Capacitive Touch Key PCB Design. First introduce the Touch Sensor Channel Selection. Touch Sensor Channels. ML56 series supports up to 14 touch sensor channels. #Reference Sensor It is recommended to select one reference sensor at touch sensor channel TK7 or TK14. Maximize the distance between the reference sensor and other signals to minimize crosstalk. #Shield Electrodes Put the shield electrode around the touch sensor to get better signal quality and waterproof capability. Recommended to select shield channel at touch TK0, TK4 or clock out pins (P3.2 / P4.6 / P5.7). Next, we will explain the PCB Layout Rules. #Touch Key Shapes Recommended to have a 10 x 10 mm sensor area for good touch key sensitivity. Larger touch sensor electrode work better for thicker cover. #Reference Sensor Recommended to assign the reference key at touch channel TK7 or TK14. Maximize the distance to other signals to minimize crosstalk. Round shape electrode with 1 mm diameter size is enough for normal case. #Ground Plane It is recommended that the traces of the touch key have a good hatched ground plane surround. It is recommended to have hatched ground plane under the touch keys. Hatched ground plane with 6 mil trace and 50 mil grid. #Shield Electrode Put touch keys with shield electrode around which provides the same phase signal around touch keys. Hatched shield electrode with 6 mil trace and 50 mil grid. Shield electrode area needs to keep filled around the touch key in greater than 10 mm width. Finally, explain the Touch Key Cover Thickness. As the cover thickness increases, the touch key sensitivities will decrease. Larger touch key size work better for thicker cover. Recommended touch key diameter size with difference acrylic cover thickness as shown in the table. 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

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