AKM AK4160 16路容性触摸传感器解决方案

关键词： AK4160 , AKM , 容性触摸传感器

AKM公司的AK4160是低工作电压和低功耗16路容性触摸传感器,其中的8路可配置成LED驱动器或GPIO,对每个传感端子具有自动的环境漂移修正功能,I2C串行接口,带S/H电路的10位SAR ADC,并集成了稳压器.主要用在手机,PC和家用电器.本文介绍了AK4160主要特性,方框图,16路触摸开关连接图以及8路触摸开关和8路LED显示器连接图,评估板AKD4160-A功能,方框图,电路图和元件布局图.

The AK4160 is a low operating voltage and low power consumption 16-channel capacitive touch sensor.

Maximum 8 channels out of the 16-channel can be configured to LED drive or GPIO. The AK4160 has a channel independent automatic correct function of environmental drifts for each sense input. It reduces false detection by continuous calibration of the internal reference value in the situation when the input capacitance of the touch switch is changed by the external factors such as hydrothermal conditions. The automatic initial setting function sets the charge current and charge time according to the size and the shape of a touch switch. The AK4160 can be configured via serial interfaces, it is suitable for mobile phones, PCs and home electric applications.

AK4160主要特性:

􀂄 Up to 16 capacitive sensor inputs

􀂄 Up to 8 general purpose inputs/outputs with PWM control for LED

􀂄 Automatic initial setting function for the charge current and time

􀂄 Independent automatic environmental drifts correct function for each sense terminal

􀂄 Independent threshold configuration for each sense terminal

􀂄 Selectable multi touch feature

􀂄 Integrated Median Averaging Filter

􀂄 Selectable 3 interrupt outputs that be able to use as GPIOs

􀂄 Reset Input pin

􀂄 I2C Serial Interface

􀂄 10 bit SAR A/D Converter with S/H circuit

􀂄 Integrated Regulator

􀂄 Low Power Consumption: Typ. 3.4uA (Sampling rate=512ms, 16ch Sensor input Active)

􀂄 Power Down Current: Typ. 1.0uA

􀂄 Low Power Operation: VDD = 1.71V ~ 3.6V

􀂄 Operating Temperature: Ta = -40 ~ 85℃

􀂄 Package: 28pin QFN (4.0mm x 4.0mm, pitch 0.4mm)

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图1.AK4160方框图

The touch switch (capacitor) that is connected to the sense input is charged up with direct current during a given period of time. The switch is connected to ground before the measurement. As a result, the touch switch capacitance is completely discharged before start being charged. When the touch switch is fully charged, the voltage is inversely proportional to the capacitance. When the touch switch is touched, this charge voltage decreases because the capacitance value when the switch is touched is larger than when not touched. The charged voltage is converted to a digital data by ADC. The data is get through the noise reduction filter, and compared to a touch threshold value. When the measurement value exceeds the threshold that is corrected environmental drifts, the AK4160 updates the status register to the touch detected state.

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图2.AK4160触摸传感器框图

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图3.AK4160 16路触摸开关连接图

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