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[FAQ] FDC2x1x Capacitive Sensing FAQs

Other Parts Discussed in Thread: FDC1004, FDC2214, LDC1101, LDC1612, LDC1312, TIDA-00317, TIDA-00373, TIDA-00506, TIDA-00220, TIDA-01409, TIDA-00466, FDC1004EVM, FDC2114EVM, FDC2114, FDC2214EVM, ENERGIA, FDC2212, FDC2112

FDC2x1x Capacitive Sensing FAQs

 For additional information, please see the FDC1004 Capacitive Sensing FAQs:

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.



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

Capacitive Proximity Sensing Using FDC2x1y

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?

Inductive Sensing App Notes with Useful Info for Capacitive Sensing Circuits using the FDC2x1y

Measuring Rp of an L-C Sensor for Inductive Sensing

Optimizing L Measurement Resolution for the LDC161x and LDC1101

Setting LDC1312/4, LDC1612/4, and LDC1101 Sensor Drive Configuration

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 )

Automotive Capacitive Kick-to-Open Reference Design - TIDA-01409

(FDC2212-Q1 , SN74LVC1G04-Q1 , TPS7B69-Q1 )

Noise-immune Capacitive Proximity Sensor System Reference Design - TIDA-00466

(FDC2212 , FDC2214 , CSD25310Q2 )


FDC1004EVM - 4 Channel Capacitive to Digital Converter Evaluation Module

FDC2114EVM - FDC2114 with Two Capacitive Sensors Evaluation Module

FDC2214EVM - FDC2214 with Two Capacitive Sensors Evaluation Module


Capacitive Sensing Sample Code (Energia)

Sensing Solutions EVM GUI Tool

FDC211x/FDC221x Current Consumption Estimator





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



Resonant LC Tank

Switched Cap

Supply Voltage



I active



Sensor Current



Sensor driving Frequency

0.1Mhz - 10 MHz

25 kHz

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

Discontinuous Sin Driver

Continuous CLK driver

Effective resolution

12/28 bits depending on the LC frequency

16 bits

Gain error



Gain Error over temp

Depends on External LC

37.5 ppm/C





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.



FDC2x1x frequently asked questions:

  • When is the FDC2x1x a bad fit for my capacitive sensing application?
     The FDC2x1x family of devices uses a resonant LC tank topology instead of the traditional switched capacitor architecture. It also does not include a dedicated shield driver pin. For this reason, usually FDC1004 is the better choice for liquid level sensing applications. For other types of capacitive sensing, TI's capTIvate family is the better choice.
    The main challenges for the FDC2x1x are:
  1. Requires an external inductor for each channel.
  2. Poor EMI/EMC performance
  3. Difficult to tune for different systems


  • Can the FDC2x1x be used for proximity detection?
    The FDC2x1x family of devices can be used for proximity detection, with the caveats discussed just above. For more information, please see the app note Capacitive Proximity Sensing Using FDC2x1y,
  • Which FDC2x1x device should I use?
  1. Determine the number of channels needed for your system
  2. For precision applications, start with the FDC221x family of devices for initial evaluation. The FDC211x, lower resolution devices are pin for pin compatible and can be tested after suitability with the higher resolution device is proven. 







28 bits

12 bits

28 bits

12 bits

Number of channels






  • What is the effective resolution of the FDC221x?
    While the following app note focuses on inductive sensing:
    The concepts explained for the LDC161x devices also apply to the FDC221x.
  • How do I choose the IDRIVE setting for the FDC2x1x?
    While the following app note focuses on inductive sensing (, the concepts explained for the LDC161x and LDC131x also apply to the FDC2x1x.
  • How can I improve EMI/EMC performance with the FDC2x1x?
    The passive filtering and supply/return routing recommendations from the following app note are applicable to the FDC2x1x:
  • How can the FDC2x1x power consumption be reduced?
    Device power consumption can be reduced with duty-cycling and clock-gating techniques. Details are available in the app note Power Reduction Techniques for the FDC2214/2212/2114/2112 in Capacitive Sensing Applications