Inductive Sensing TouchOnMetal Buttons （感应传感TouchOnMetal按钮）.pdfVIP

Application Report SNOA951– June 2016 Inductive Sensing Touch-On-Metal Buttons Design Guide Ben Kasemsadeh, Luke LaPointe ABSTRACT This application note covers the fundamentals of Touch-on-Metal (ToM) technology using an LDC1612 Inductance-to-Digital Converter (LDC) and provides guidance for constructing ToM buttons. Simple on and off buttons can be easily implemented using inductive sensing. Additionally, by using a high resolution LDC, microscopic movements in a flat metal button can be sensed and processed to determine how hard a given button was pressed. This approach allows reuse of existing metal surfaces commonly found in many applications such as consumer electronics and appliances. This report contains a design example for a multi-button brushed aluminum panel and provides guidance on the mechanical system and sensor design, as well as measured performance results of the complete system. Contents 1 ToM Basics 1 2 How Are Inductive Touch-On-Metal Buttons Implemented? 2 3 System Design Procedure 3 4 Results 18 5 Summary 20 6 Additional resources 20 1 ToM Basics ToM buttons refers to using a flat metal surface as a button and a high resolution inductance converter such as the LDC1612 to detect the microscopic metal deflection that occurs when the button is pressed. Figure 1 shows a block diagram of a touch-on-metal solution with two buttons