topic PN5180 Symmetry on RXN and RXP pins. in NFC

PN5180 Symmetry on RXN and RXP pins.

nike9307 — Wed, 16 Feb 2022 10:59:12 GMT

According to AN11740 - The AGC only measures the Rx voltage level of the RxP. Normally the voltage
level at RxN and RxP should be the same. However, in case of wrong assembly
or a bad symmetry the voltage level might be different at both pins.

I've measured the levels on RXN and RXP with 1.5pF active probe and with fixed AGC with no load, as per AN11740. Thea asymmetry between the two pins is around 1%. I believe that this is mostly due to the 1% external resistors.

How much is an acceptable level of asymmetry between those two pins for EMV V3.1?
Would the PN5180 receiver circuit benefit from the use of 0.5% or 0.1% resistors?
What is the tolerance of the resistors used in the PN5180 dev kit?

Re: PN5180 Symmetry on RXN and RXP pins.

fangfang — Mon, 21 Feb 2022 02:22:36 GMT

Hello @nike9307 .

>> How much is an acceptable level of asymmetry between those two pins for EMV V3.1?
Unfortunately. There is no the detail information. But the development board of PN5180 passed the EMV V3.1.
The customer can refer to the board.

>>Would the PN5180 receiver circuit benefit from the use of 0.5% or 0.1% resistors?
>>What is the tolerance of the resistors used in the PN5180 dev kit?
Please kindly find the BOM of the development board of PN5180 as I sent it to you via email.

Have a nice day.

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Re: PN5180 Symmetry on RXN and RXP pins.

nike9307 — Mon, 21 Feb 2022 09:03:35 GMT

Hello @fangfang

Thank you for the quick reply.

The BOM does not contain any tolerance values for the components. I'm guessing they are probably 1%.