AD7142
Analog Devices
Analog Devices’ capacitance sensing solution has three components: the AD7142 capacitive-to-digital converter IC
Application NoteAnalog
AN-830: Factors Affecting Sensor Response
This application note examines how sensor size, object size, and covering material thickness affect capacitance sensor response using the Analog Devices AD7142 CDC.
Overview
This document details the factors influencing the performance of capacitance sensors used with the Analog Devices AD7142 capacitive-to-digital converter (CDC). It identifies three primary factors affecting sensor response: the size and type of the sensor element (button or slider), the size of the object touching the sensor (simulated finger size), and the thickness and dielectric properties of the covering material. The note provides experimental data using ABS plastic of varying thicknesses and grounded metal probes to demonstrate how these variables impact the CDC output code. It also includes a table of dissipation factors for various polymers and offers design recommendations, such as maintaining a maximum covering thickness of 2 mm for optimal sensor sensitivity and resolution.
Use Cases
- User interfaces for mobile phones
- Control panels for digital cameras
- Scrolling mechanisms for MP3 and portable media players
- Touch-sensitive controls in consumer electronics
- Proximity sensing through plastic or glass enclosures
Topics
AD7142
capacitance sensing
capacitive-to-digital converter
CDC
sensor response
button sensor
slider sensor
dissipation factor
PCB sensor design
Referenced Parts
| AD7142 | Analog Devices | Analog Devices’ capacitance sensing solution has three components: the AD7142 capacitive-to-digital converter IC |