topic PN5190 Selecting Rrx. in NFC

PN5190 Selecting Rrx.

nike9307 — Tue, 22 Nov 2022 10:56:04 GMT

Hi,
According to the "PN5190 antenna design guide" document, on point "6.1 Correct RX coupling" the way to tune the value of Rrx is to "4. Read H_ATT_VALUE, RX_CONTROL_STATUS register (0x28), bit 3…8" and change the resistor until its 40.
In the current datasheed Rev. 3.5 that register doesn't exist, the closest i could find was the RX_CTRL_STATUS and RXCTRL_HF_ATT_VAL. Is it the same register described in the antenna design guide?
EDIT: The HF_ATT_VAL and RXCTRL_STATUS names were also sued in the "PN5190 design-in recommendations" document.

Also I believe there is a typo in the design guide, H_ATT_VALUE may refer to HF_ATT_VALUE, or vice versa. I'm not sure.

On my test board, I'm getting 38 (dec) in that register. Should I aim for 40 exactly, or is 38 good enough?

Re: PN5190 Selecting Rrx.

danielchen — Mon, 28 Nov 2022 15:23:33 GMT

Hi Nike:

Yes, you are right. there is a typo. H_ATT_VALUE should be HF_ATT_VALUE.

RX_CONTROL_STATUS register (0x28) , is RX_CTRL_STATUS. Sorry a bit confusing. Thanks for your feedback. I will report it to the doc team.

This value shall be ≈ 40 dec, so 38 is also ok.

Regards

Daniel