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I am not sure if this is right place for this question.

NFC bandwidth can go up to 50KB per second, and there are NFC business cards that have EPROM up to 8kb.

Is there possibility to put micro SD card of 1,2 or 8gb and connect it with NFC chip to communicate with NFC reader and transfer data from that SD card? Basically like a USB stick but with NFC protocol and embedded in business card. Is this possible at all as I don't know if SD cards can work in passive mode, but if EPROM chips of 8kb can work in passive mode I am questioning if there is possibility for SD cards as well.

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    \$\begingroup\$ My guess is no. SDcards would draw too much power. \$\endgroup\$
    – Kartman
    Commented Apr 28, 2021 at 13:48
  • \$\begingroup\$ Is there some alternatives for SD cards, like low power SRAM chips? Or is there possibility to add small sized battery like on old game consoles catriges? \$\endgroup\$
    – dejanmilosevic0
    Commented Apr 28, 2021 at 13:55
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    \$\begingroup\$ Your last comment completely changes the nature of the question. I suggest that you take some time to figure out what you really need and then write a new question. \$\endgroup\$
    – Elliot Alderson
    Commented Apr 28, 2021 at 15:17

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The main problem will be power. All the energy needs to come from the field. The maximum available power will be approximately 30 mW. But this is the best case. I would probably calculate with 10 mW. If you want to access a SD-card you need the right interface. Therfore a microcontroller is needed. I think power consumption of microcontroller and SD-card will be more than 10mW.

There are now two possibilities:

  • find a ultra-low-power microcontroller and other memory that draws less than 10mW

  • find an NFC-Tag-IC that can interface with some kind of non-volatile memory

I looked up for memory chips with at least 1GByte. The interface that is used is eMMC. The power consumption of these chips can get very low with low frequencies. But you need a suitable microcontroller with very low power consumption and an eMMC interface.

I would prefer the second option. There are NFC-Tag-ICs that can act as I2C-master (e.g. NTAG 5 boost). With these kind of ICs there is no need for a microcontroller. All you need is I2C memory. I also looked up memory for this but could only find chips with a maximum capacity of 2Mbit. This is propably due to the I2C adress.

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