NFC

RE: NFC

JONATHAN LL — Mon, 16 Mar 2026 12:25:22 GMT

Hi, Could you also maybe create a new public ticket where you share some more details about you setup and what versions of the SW you are using as such.

Its easier for us to follow up with some more info available.

Regards,
Jonathan

RE: NFC

collins — Mon, 16 Mar 2026 08:33:32 GMT

I’m trying to enable NFC on my Nordic device but sometimes the tag is not detected by my phone. Has anyone experienced this and found a reliable solution?

2 player games

RE: NFC

Wm_Post — Mon, 15 Dec 2025 17:09:02 GMT

Abricon does not have any reference designs/evaluation boards for their NFC chip antennas. They already provide the PCB footprint inside their datasheets - this one (https://abracon.com/datasheets/AANI-CH-0030.pdf) IS accurate. A NFC chip antenna is essentially an inductor, so only the right capacitor (parallel capacitance combining internal chip cap plus external cap) is needed to resonate at 13.56MHz - it’s an LC parallel circuit.

RE: NFC

JONATHAN LL — Thu, 16 Oct 2025 14:00:44 GMT

Happy to help so feel free to ask some follow questions here if you need. We are here to help!

Regards,
Jonathan

RE: NFC

mej7000 — Thu, 16 Oct 2025 13:13:20 GMT

That's good advice. I will try that approach. I ordered a VNA for testing.

RE: NFC

JONATHAN LL — Thu, 16 Oct 2025 08:32:35 GMT

[quote user="mej7000"]For Lant = 3.1 μH and Cint1 = Cint2 = 5 pF on nRF54L15, use Ctune1 = Ctune2 ≈ 17 pF (each from NFC1/NFC2 to ground) to achieve 13.56 MHz resonance, as per the official recommendations.[/quote]

This is sounds reasonable.

I personally like to start with the antennas recommendations and then work my way up in cap values to see how the resonance moves and adjust accordingly, but this seems ok.

Regards,
Jonathan

RE: NFC

mej7000 — Wed, 15 Oct 2025 22:31:49 GMT

I think I understand the NFC matching network now... I am guessing that Parasitic Capacitance will require me to drop the Ctune value to something less that 17.2pF, but as a starting point, do you agree that these calculations are correct?
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using docs.nordicsemi.com/.../nfct.html and docs.nordicsemi.com/.../parameters.elec_spec.html as a reference what value should what are the values of Ctune1 and Ctune2 if Ctune1=Ctune2 and Cint1=Cint2=5pf on the nrf54L15 and Lant = 3.1uH to achieve 13.56Mhz and how should those capacitors be arraigned?

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To achieve resonance at 13.56 MHz with an antenna inductance (Lant) of 3.1 μH on the nRF54L15, and given that the internal capacitance per pin (Cint1 = Cint2 = 5 pF), you need to calculate the value of the external tuning capacitors (Ctune1 = Ctune2) to be connected from NFC1 to ground and NFC2 to ground.

Calculation

The resonance frequency for the parallel LC circuit is:

f = 1 / (2π * sqrt(L * C_total))

Where:

f = 13.56 MHz
L = 3.1 μH
C_total = Cint1 + Ctune1 (for NFC1) and Cint2 + Ctune2 (for NFC2)

Since the circuit is symmetric and Ctune1 = Ctune2, Cint1 = Cint2, the total capacitance across the coil is (Cint1 + Ctune1) + (Cint2 + Ctune2).

Step 1: Calculate total required capacitance

C_total = 1 / ( (2πf)^2 * L )

Plug in the values:

f = 13,560,000 Hz
L = 3.1 × 10⁻⁶ H

C_total = 1 / ( (2 * π * 13,560,000)^2 * 3.1e-6 )
        ≈ 1 / ( (85,237,000)^2 * 3.1e-6 )
        ≈ 1 / (7.269e15 * 3.1e-6)
        ≈ 1 / (2.254e10)
        ≈ 44.4 pF

Step 2: Subtract internal capacitance

The total internal capacitance is Cint1 + Cint2 = 5 pF + 5 pF = 10 pF.

C_external_total = C_total - (Cint1 + Cint2)
                 = 44.4 pF - 10 pF
                 = 34.4 pF

Step 3: Divide by two for each external capacitor

Ctune1 = Ctune2 = C_external_total / 2
                   = 34.4 pF / 2
                   = 17.2 pF

Arrangement

Connect one 17 pF capacitor from NFC1 to ground.
Connect one 17 pF capacitor from NFC2 to ground.

This matches the recommended arrangement in the nRF54L15 documentation, where the antenna coil is connected differentially between NFC1 and NFC2, and each pin has a tuning capacitor to ground to achieve resonance at 13.56 MHz NFCT antenna recommendations – nRF54L15.

Note: Use the closest standard value (e.g., 18 pF if 17 pF is not available) and fine-tune as needed for your specific PCB and antenna.

Summary:
For Lant = 3.1 μH and Cint1 = Cint2 = 5 pF on nRF54L15, use Ctune1 = Ctune2 ≈ 17 pF (each from NFC1/NFC2 to ground) to achieve 13.56 MHz resonance, as per the official recommendations.

RE: NFC

JONATHAN LL — Tue, 14 Oct 2025 12:40:22 GMT

[quote user="mej7000"] or do you know of anything similar that others have had success with?[/quote]

Most customers often use some version of the flex PCB NFC antenna and fold it over the PCB in a way.

I dont have a specific recommendation on small NFC antennas.

I always recommend that our customers contact the antenna manufacturers to get the best help on the options here, as we are not an antenna company.

We will help with tuning if that is something you wish, but we can not guarantee a great result but we will do our best and provide feedback and result of the tuning process.

Regards,
Jonathan

RE: NFC

mej7000 — Mon, 13 Oct 2025 15:59:04 GMT

Thanks. The 20x10mm trace makes AANI-CH-0030 unusable.

www.digikey.com/.../12525163 antenna doesn't specify a large trace. Just a single Tuning Cap... This is the kind of NFC antenna footprint I am looking for. I can design RFPCA080500NNFB001 in, or do you know of anything similar that others have had success with?

RE: NFC

JONATHAN LL — Mon, 13 Oct 2025 13:50:32 GMT

[quote user="mej7000"]Can you send the link to the one you found?[/quote]

https://eu.mouser.com/datasheet/3/184/1/AANI-CH-0030.pdf from here: https://eu.mouser.com/ProductDetail/ABRACON/AANI-CH-0030?qs=mELouGlnn3cTcji%252Bc8GYNQ%3D%3D

[quote user="mej7000"]Also, weird that "C5" is a 220nH Inductor? Does that seem right? Typo?[/quote]

Difficult to say, these Abacron antennas have strange matching networks sometimes. Always best to check with the manufacturing for propper clarity on these cases.

Regards,
Jonathan

RE: NFC

mej7000 — Mon, 13 Oct 2025 12:51:55 GMT

Thanks! The datasheet I have doesn't have that information. https://abracon.com/datasheets/AANI-CH-0030.pdf

Also, weird that "C5" is a 220nH Inductor? Does that seem right? Typo?

Can you send the link to the one you found?

RE: NFC

JONATHAN LL — Mon, 13 Oct 2025 09:25:58 GMT

[quote user=""]AANI-CH-0030 NFC chip antenna from[/quote]

You need to follow the recommendations for this antenna and you can also consult Abacron on this.

Looks like they have this from there datasheet on the antenna, I would try and follow this.

We have some info on tuning here: https://devzone.nordicsemi.com/nordic/nordic-blog/b/blog/posts/nfc-tag-antenna-tuning
https://docs.nordicsemi.com/bundle/ps_nrf54L15/page/nfct.html#ariaid-title11

Then there is the paper as well, https://docs.nordicsemi.com/bundle/nwp_026/page/WP/nwp_026/nWP_026_network_analyzer.html

The AI response here is not to far off, but I would not bet on it as with most ting related to antennas the tuning is best done when measured. Effects of the layout and other changes in the HW can effect the result of the antenna so there is not really a guaranteed way to see if it is a good match other then to just check with a VNA or an alterative solution.

Looks like you are also using a module of sorts here so pin capacitance value might also be a bit different. I dont have the cap value of the pins on the nRF54L15 on the NFC pins when configured for NFC use.

Regards,
Jonathan