ST sells ST25TV Type 5 tag chips with a 23pF / 99.7pF option. What bearing does that option have on read range and other interactions with a reader like the ST25R3911B? No info that I can find in the datasheet.

[Ted Jackson]

Also, has anyone experimented with large (several cm diameter) single loop antennas on the tag side?

[Berenice BENVEGUDA]

Hello Ted,

First of all thanks for your interest in ​ST25TV chip.

ST25TV tag chips is sold either with 23 pF, either with 99.7 pF.

The choice is related to the antenna design you plan for the tag : 99.7pF option is meant to allow smaller antenna design compare to 23pF version.

Best Regards,

BB

[Ted Jackson]

Thanks for that, Berenice. Is there any other further technical information relating to the design of the tag antenna and the EM interactions between readers and tags that you're aware of?

[Berenice BENVEGUDA · Accepted solution]

​Hello Ted,

You can refer to the following application note available on web site :

https://www.st.com/resource/en/application_note/cd00221490-how-to-design-a-1356-mhz-customized-antenna-for-st25-nfc--rfid-tags-stmicroelectronics.pdf

I hope this helps,

Best Regards,

BB

[Ted Jackson]

Thank you so much, Berenice. Would you happen to know if the M24LR04E-R Dynamic NFC RFID tag ICs (having as they do an I2C and an RF interface) can be employed entirely in RF mode (with no I2C interaction whatsoever)?

[Ted Jackson]

My first thought was to compare the square spiral antenna model with the result of the ST's eDesign antenna. And the numbers produced are about three orders of magnitude different. Am I missing something?

[Berenice BENVEGUDA]

​Hello Ted,

for sure you can use M24LR04E-R Dynamic Tag without using I2C interface.

Best Regards,

BB