Pls help check schematic diagram

RE: Pls help check schematic diagram

Wu Yewan — Sat, 24 Oct 2026 03:07:43 GMT

I still have one more question that I'd like to consult.
Our NFC coil and QI coil are integrated together. Similar to the following picture

To reduce the impact of QI on NFC, I connected a 100pf capacitor in series in the circuit. As shown in the following figure, the NFC1 NFC2 network is connected to the nRF54L15. Connect the NFC_in1 and NFC_in2 coils.

My NFC and QI don't work simultaneously. I also know that adding 100pF of capacitance will reduce the sensitivity. But this is also a reluctant move.
I'd like to ask, if capacitors must be connected in series at this place, what size of series connection is appropriate? Or are there any other good ways?
My QI charging power is very low, not exceeding 1 watt.

Thanks,

Curry.

RE: Pls help check schematic diagram

Nissanth — Fri, 23 Oct 2026 08:00:02 GMT

Hi again,

I tested this with the NFC1 and NFC2 connections swapped, and tag reading works the same in both cases. You can keep the crossover as it is. The antenna network is symmetrical, with the same load on both pins.

Best regards,
Nissanth Karunanithy

RE: Pls help check schematic diagram

Wu Yewan — Fri, 23 Oct 2026 01:21:04 GMT

Or perhaps it's just that the online name is reversed, and the performance is not affected.
The reason for the engineers' crossover is that when laying out the pcb, they found it was not smooth, but after the crossover, it became smooth.

Thanks,

Curry.

RE: Pls help check schematic diagram

Wu Yewan — Fri, 23 Oct 2026 01:15:04 GMT

Hi Team,

The R&D has a question , The nfc coil is completely symmetrical. Is there any problem with network switching? Or, what impact will the forward or reverse insertion of the coil have on card reading ?

Thanks,

Curry.

RE: Pls help check schematic diagram

Nissanth — Thu, 22 Oct 2026 08:12:04 GMT

Hi,

Feedback 1: C35 should be 2.2 nF on DECRF pin.

Feedback 2: Add a 3.9 pF capacitor at nRESET, placed right at the pin, as in the reference. See image below.

Reference below,

Feedback 3: The ANT matching network does not match Nordic’s reference. The first series inductor is missing, and the component values differ. Copy the reference as shown below.

Reference below,

Feedback 4: Both pin 5 (P1.04) and pin 6 (P1.05) are labelled UARTE20_TXD. One of them must be UARTE20_RXD.

Feedback 5: The NFC net labels are crossed. Pin 3 (P1.02/NFC1) goes to net NFC2, and pin 4 (P1.03/NFC2) goes to net NFC1.

Feedback 6: Typo on pin 21

Rest of the schematic looks fine. Make sure the footprint is close to our reference schematic, most important for the ANT network and the supply. If you can send me the datasheet for the crystals, I can check them too.

Best regards,
Nissanth Karunanithy