FDC2214EVM: Sensor design and optimization

Alessandro Sardellitti

Part Number: FDC2214EVM
Other Parts Discussed in Thread: FDC2214, FDC1004EVM, LDC1612EVM, FDC1004, LDC1312, FDC2112, FDC2212, LDC1612

Tool/software:

Hi everyone,
I'm currently working with the FDC2214EVM – High Resolution L-C Sensing Evaluation Module, and I’m looking for more detailed information about the recommended range of inductance, capacitance, and resistance for the LC sensors that can be connected to the FDC2214.

I’ve found some general specifications in the documentation:

Sensor Type: LC Resonant Circuit (Inductance + Capacitance)
Sensor Operating Frequency: 10 kHz – 10 MHz (optimal: 1–5 MHz)
Typical Inductance: 1 µH – 20 µH
Typical Capacitance: 10 pF – 330 pF
Recommended Quality Factor (Q): Q > 10, ideally Q > 30 for better sensitivity and stability
Recommended Parallel Resistance (RP): RP > 300 kΩ

Are there any official guidelines or application notes from TI (or community experience) that suggest more specific recommended or optimal ranges for L, C, and RP in different use cases or sensor configurations?
I’d also be interested to know if there are any software tools or calculators that can help with the design of LC sensors (e.g., selecting appropriate inductor/capacitor values, estimating resonant frequency, Q factor, or simulating sensor behavior).

Are there similar tools also for FDC1004EVM and LDC1612EVM?

Any suggestions, links would be greatly appreciated!
Thanks in advance!

6 months ago

+1 John Miller - Sensing 6 months ago

TI__Mastermind 40295 points

Alessandro,

Thank you for your interest in our inductive and capacitive sensors. We have tools & resources to support these devices.

Inductive Sensing

For inductive sensors, a good place to start is the [FAQ] Inductive sensing FAQ - Frequently asked questions page for tips and resources for using these devices.
For help with coil design and device settings, please download & use the Excel-based Inductive Sensing Design Calculator Tool.
The app notes LDC Sensor Design and LDC Target Design offer advice on best-practices for your sensor and target designs.
EMI Considerations for Inductive Sensing and Setting LDC1312/4, LDC1612/4, and LDC1101 Sensor Drive Configuration have useful info as well.
You can use inductive sensors for capacitive sensing by simply changing the sensor from a coil +PCB cap to a plate capacitor + PCB inductor.
The app note Resonance-Based Capacitive Sensing Using LDC2114 covers this topic for that device (and the LDC3114), but the principle can be extended to all of our inductive sensors.

Capacitive Sensing

The FDC1004 is a non-resonant capacitive sensor. Please see the E2E FDC1004 Frequently Asked Questions page for a comprehensive list of supporting app notes and other collateral. The page also has a crash course for this device that gives an overview and a deep-dive into the major specs and features of the device.
The FDC2x1y series of devices are resonant-sensor based capacitive sensors that share an internal architecture that is very similar to the LDC131x and LDC161x devices.
There is no dedicated design tool for the FDC1004 yet, but you can use the Inductive Sensing Design Calculator Tool to help optimize device settings for the FDC2x1y devices using the LDC131x_LDC161x_Config tab in the tool. The equivalence is FDC2112/4 ≈ LDC1312/4 and FDC2212/4 ≈ LDC1612/4.
For more information on the FDC2x1y family, please see Capacitive Proximity Sensing Using FDC2x1y
There is an FAQ page for the FDC2x1y family that will be available soon. Please keep and eye out for it on our TI/Sensing E2E forum page.

I hope this helps. Please let me know if you have any questions.

Regards,
John

Sensors

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FDC2214EVM: Sensor design and optimization