SNOAAA5 April   2024 DRV8220 , FDC1004-Q1 , LDC3114-Q1 , TMAG5131-Q1 , TMAG5173-Q1 , TMAG6180-Q1

 

  1.   1
  2.   Abstract
  3.   Trademarks
  4. 1Introduction
  5. 2Automotive Door Handle Architectures
  6. 3Functional Demo Design
  7. 4Detailed Design Flow for Door Handle Functions
    1. 4.1 Door Open or Closed Detection With Magnetic Sensing
      1. 4.1.1 Demo Implementation of Open Close Detection Using TMAG5131-Q1
    2. 4.2 Deployable Door Handle Position Detection With Magnetic Sensing
      1. 4.2.1 Demo Implementation of Deployable Door Handle Position Sensing Using TMAG6180-Q1
    3. 4.3 Hand Proximity Detection With Capacitive Sensing
      1. 4.3.1 Overview of Capacitive Sensing Applications
      2. 4.3.2 Examples of Soft-Touch Detection Based on Capacitive Sensing in a Door Handle Demo
        1. 4.3.2.1 Touch Button
        2. 4.3.2.2 Door Handle
    4. 4.4 Push Button With Inductive Sensing
      1. 4.4.1 Inductive Push Buttons
      2. 4.4.2 Inductive Push Button Sensitivity
      3. 4.4.3 Target Material
      4. 4.4.4 Target Distance and Sensor Size
      5. 4.4.5 Design Example
  8. 5Summary
  9. 6References

1 Introduction

This document provides a high-level overview of automotive door handles and the potential features, and how such features can be achieved using magnetic, capacitive, and inductive sensors. Design examples presented are based on a demo, which is also featured in the demo video Designing with position sensors: Automotive door handles and the Position Sensing in Automotive Door Handle Systems application brief.

The demo is used as a foundation to illustrate the use of Hall-based sensors to monitor door open/closed position, and discusses the design considerations and capabilities of Hall sensing technology for this application. This is supported by simulations in TI Magnetic Sense Simulator (TIMSS), TI's online simulator for magnetic position sensors.

The demo also illustrates capacitive-sensing technology as the basis for a touch button to detect a user's finger or hand, which can subsequently deploy a recessed door handle. Once the handle is deployed, a capacitive sensor can then detect the presence of a user's hand on the handle to prevent the handle closing on the user's hand. Approximate mathematical models are given to provide the user a starting point for a design, and the approximations are confirmed by the demo. References to other capacitive sensing application notes with supporting information are given throughout.

Also included in this application note is the use of inductive sensors for push-button applications (as opposed to a capacitive touch button). This technology is not included in the demo, but is a popular feature in many of today's vehicles. That section covers design and implementation-related considerations and provides a more detailed design example of a push-button sense coil using the Inductive Sensing Calculator Tool.