Application NoteInfineon

AN64846: Getting started with CAPSENSE™

An introductory guide to Infineon CAPSENSE™ capacitive touch technology, covering hardware design, CSD and CSX sensing methods, layout, and EMI considerations.

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Overview

This application note provides a comprehensive introduction to Infineon CAPSENSE™ capacitive touch sensing technology. It details the underlying principles of self-capacitance (CSD) and mutual capacitance (CSX) sensing methods. The document outlines essential design considerations including schematic development, PCB layout, ground plane optimization, and overlay material selection. It also covers performance optimization through SmartSense auto-tuning, Signal-to-Noise Ratio (SNR) measurement, and software filtering. Specialized topics include liquid tolerance, proximity sensing, and EMI/EMC compliance strategies for PSoC and CAPSENSE Express devices. Protection techniques for ESD are also discussed, referencing components such as the Littelfuse SP723, Vishay VBUS05L1-DD1, and NXP NUP1301.

Use Cases

Developing touch-sensitive interfaces for consumer electronics and appliances
Implementing water-resistant capacitive buttons and sliders
Designing low-power proximity sensors for wake-on-approach features
Optimizing PCB layout for capacitive sensors to minimize electromagnetic interference
Selecting appropriate Infineon PSoC devices for capacitive touch applications

Topics

CAPSENSE

Capacitive Touch

PSoC 4

PSoC 6

SmartSense

CSD sensing

CSX sensing

EMI/EMC

Liquid Tolerance

Proximity Sensing

ESD Protection

Infineon

Referenced Parts

VBUS05L1-DD1

Vishay

Vishay VBUS05L1-DD1 0.3 pF 0.1 μA 15 kV 16 kV

PSoC 3

Infineon

PSoC™ 3 and PSoC™ 5LP development kits

PSoC 4

Infineon

PSoC™ 4 development kits

PSoC 5LP

Infineon

PSoC™ 3 and PSoC™ 5LP development kits

PSoC 6

Infineon

PSoC™ 6 development kits

CAPSENSE Express

Infineon

configurable CAPSENSE™ controllers (CAPSENSE™ express family)

SP723

Littelfuse

Littelfuse SP723 5 pF 2 nA 8 kV 15 kV

NUP1301

NXP

NXP NUP1301 0.75 pF 30 nA 8 kV 15 kV

VBUS05L1-DD1	Vishay	Vishay VBUS05L1-DD1 0.3 pF 0.1 μA 15 kV 16 kV
PSoC 3	Infineon	PSoC™ 3 and PSoC™ 5LP development kits
PSoC 4	Infineon	PSoC™ 4 development kits
PSoC 5LP	Infineon	PSoC™ 3 and PSoC™ 5LP development kits
PSoC 6	Infineon	PSoC™ 6 development kits
CAPSENSE Express	Infineon	configurable CAPSENSE™ controllers (CAPSENSE™ express family)
SP723	Littelfuse	Littelfuse SP723 5 pF 2 nA 8 kV 15 kV
NUP1301	NXP	NXP NUP1301 0.75 pF 30 nA 8 kV 15 kV