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[FAQ] FDC1004 Capacitive Sensing FAQs

Part Number: FDC1004
Other Parts Discussed in Thread: FDC2214, TIDA-00317, TIDA-00373, TIDA-00506, TIDA-00220, , ENERGIA, FDC2212

 What are the differences between Capacitive Sensing Versus Capacitive Touch Solutions.

Texas Instruments provides solutions for capacitive sensing and capacitive touch applications, which share some important similarities and some crucial differences. Capacitive sensing applications can require relatively large target distances and/or higher resolution than capacitive touch applications.

The table below offers a brief comparison between the similarities and differences between these two applications


Capacitive Sensing

Capacitive Touch

Channel count

Low (< 4)

High (> 8)




Typical distance

Up to 70 cm

2 to 3 mm


< 1 fF

10s to 100s fF

Requires contact



Power consumption

μA range

μA to mA range

For more information on capacitive touch solutions, please consider TI's capTIvate as the best fit for this application.

See the Getting Started Guide and a selection of CapTIvate Devices here.


What applications can/can’t be supported by capacitive sensing?

  1. Liquid Level Sensing
    For most non-conductive liquid level sensing applications (including water), the FDC1004 should be used. The FDC1004 has an active shield driver which helps the system against interference from environmental factors.

  2. Non-Metal Proximity Sensing
    The FDC1004 is the best choice, since the FDC2x1x does not have a shield driver, can and requires advanced system level expertise.

  3. What applications do not work with TI's capacitive sensing technology?
    Metal detection - to detect metal, TI's inductive sensing solutions are a better option.
    See the TI E2E Inductive Sensing FAQ  Inductive Sensing FAQ 

How do I get started with Capacitive Sensing?

A list of learning and design resources, sorted by subject, are given below.


App Note Title

App Note URL

Introductory App Notes

Common Inductive and Capacitive Sensing Applications

Basics of Capacitive Sensing with FDC1004

Liquid Level Sensing App Notes

Capacitive Sensing: Ins and Outs of Active Shielding

Capacitive Sensing: Out-of-Phase Liquid Level Technique

Capacitive Sensing: Direct vs Remote Liquid-Level Sensing Performance Analysis

Liquid Level Sensing with the Immersive Straw Approach

How to Calibrate FDC1004 for Liquid Level Sensing Applications

Proximity sensing

Capacitive Proximity Sensing Using the FDC1004

General App Notes, Technical Articles and Blogs

Derivative Integration Algorithm for Proximity Sensing

Ground Shifting in Capacitive Sensing Applications

Power Reduction Techniques for the FDC2214/2212/2114/2112 in Capacitive Sensing Applications

Capacitive sensing: simple algorithm for proximity sensing

Capacitive sensing: which architecture should you choose?

TI Designs

Capacitive Based Liquid Level Sensing - TIDA-00317 (FDC1004 , MSP430F5528 )

Backlight and Smart Lighting Control by Ambient Light and Proximity Sensor Reference Design - TIDA-00373 (FDC1004 , HDC1000 , HDC1008 )

Automotive Capacitive Proximity Kick to Open Detection Reference Design TIDA-00506 (FDC1004)

Capacitive-Based Human Proximity Detection for System Wake-Up & Interrupt Reference Design - TIDA-00220 (FDC1004 , LM3630A , LP5907 )


FDC1004EVM - 4 Channel Capacitive to Digital Converter Evaluation Module


Capacitive Sensing Sample Code (Energia)

Sensing Solutions EVM GUI Tool


What are the differences between the FDC1004 and the FDC2212/2214?

The table below shows & compares the major features of the two devices.



Number of Channels


2 or 4


Switched Cap

Resonant LC Tank

Supply Voltage



I active



Sensor Current



Sensor driving Frequency

25 kHz

0.1Mhz - 10 MHz

Maximum Sensor Input


250nF @ 10Khz / 25pF @ 10 MHz

Sensor input range w/respect to input offset calibration



Input Offset Calibration



Integrated Shield Driver



Driver Architecture

Continuous CLK driver

Discontinuous Sin Driver

Effective resolution

16 bits

12/28 bits depending on the LC frequency

Gain error



Gain Error over temp

37.5 ppm/C

Depends on External LC






Poor, needs external passives



High SW and HW





  • As the table shows, the FDC1004 input is a switch-cap topology while the FDC2x12/4 uses a resonant tank. The major advantages of the FDC1004 is its integrated shield driver, which can improve the EMI/noise immunity of your circuit, and its driver architecture, which greatly reduce EMI emissions, compared to the FDC2x12/4. 

FDC1004 frequently asked questions:

  • When is the FDC1004 a bad fit for my liquid level sensing application?
    The FDC1004 does not work with conductive liquid. The FDC1004 works well for most other liquid level sensing applications, including water. For more information, see the topic Liquid Level Sensing App Notes above for a list of supporting app notes.

  • Should I use a single-ended or a differential measurement?
    Both options work can work for liquid level sensing. The advantage of the differential measurement is that it helps with immunity to environmental conditions. For more information please see the app note Capacitive Sensing: Out-of-Phase Liquid Level Technique

  • Can the FDC1004 be used for proximity sensing applications?
    The FDC1004 can be used for proximity detection, and detection of simple gestures. For more information on using the FDC1004 for proximity detection, please see the app note Capacitive Proximity Sensing Using the FDC1004 , or the reference designs &

 Capacitive sensing applications with the FDC1004 include:

1. Independent channels
The FDC1004 features 4 independent channels that are sampled sequentially in a time-multiplexed manner. Typical applications include rain sensing, proximity/gesture detection, and water/ice/snow detection.

Figure 1. Independent Channel use Case for Gesture Sensing Application

2. Differential or ratio-metric measurements
Differential measurements are performed to obtain an accurate capacitance measurement difference between two sensors. This is most applicable to environmental factors that can cause variations in capacitance, such as direct, immersive sensing, or remote liquid sensing.

 Figure 2. Differential or Ratiometric Measurements Example, Liquid Level

3. Remote sensing
Physical distances between the sensor and the device can be a major issue when accurate capacitive measurements are needed. To compensate for long signal paths, the FDC1004 allows parasitic capacitance compensation up to 100 pF which gives the FDC1004 the ability to drive a twisted pair up to 1600 m (60 fF/m) or a coax cable up to 1.5 m (66 pF/m).
Figure 3. Remote Sensing Example
4. Time-varying offset measurements
The FDC1004 can be used in the case where time-varying offset measurements are required to be monitored. A replica sensor adjusts for changes in offset from factors like humidity, environment, and water/ice/snow.
Figure 4. Time-Varying Offset Measurements Example