PN512 RX circuit design

[dc1]

Hello,

we have a PN512 chip for read the NFC tags on a device that we acquire from an our partner. I don0't have the schematics but i have done a short reverse engineering. We have some problems on the RX circuit, many time the card is not correctly readed.

I have seen on different application note that the rx circuit for the PN512 is proposed in two different ways:

• circuit 1 and 2 from Blueboard_PNEV512B_v1.5_SCH and AN1445
• circuit 3 from AN11038

in our case the circuit implemented is the circuit 3. If i switch from the circuit 3 to the circuit 1 (inverting R1 with C3) the reader seems to work better.

What are the difference between the two circuit? Which is the best? or are equivalent?

Thanks

[fangfang · Accepted solution]

Hello @dc1 ,

Thanks for your information.

The principle of receiver circuit please kindly refer to 4.6 Receiver circuit design of AN1445.
circuit 3 and 2 are the reference design. circuit 1 is the design of the development board which is verified by NXP. So we recommend the customer to follow the design if have the same antenna size.

Have a nice day.

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