In search of RFID solution having the smallest footprint possible

Hello Jorge,

the smallest possible footprint NFC tag from TI, which comes to my mind, is the RF37S114 (https://www.ti.com/product/RF37S114). It has a footprint of 4 x 4 mm including antenna coil.

What do you mean by two-way RFID solution?

Best regards,

Andreas.

Hello Andreas,

Thank you for your reply. Two-way meaning data flows from tag to reader and from reader to tag. Need to be able to write to tag and read from it. Do you have a DS for this device? This one is just a technical overview and doesn't provide detailed info. RF37S114 Tag-it HF-I Type 5 NFC, ISO/IEC 15693 Transponder, 4 mm × 4 mm datasheet (ti.com).

I would like to know if it has pins to interface with an MCU...

Hello Jorge,

it is possible to write and read to/from the RF37S114. The provided datasheet contains all necessary device details. The technical details are documented in the IS15693, to which this device is compliant to. The RF37S114 does not have any pins for MCU connection. If you want a device with pins for connecting to an MCU, then the RF430CL33xH (https://www.ti.com/product/RF430CL330H) could be an option. If you want to have the MCU included in the IC, then the RF430FRL15xH (https://www.ti.com/product/RF430FRL152H) could be of interest. It would be easier to chose the right product if you could provide a summary of your requirements.

Best regards,

Andreas.

Hello Andreas,

Thank you for that info.

Yes, probably should have started by stating the end goal.

We would like to flash a FW load ranging between 80KB-130KB of data onto an MCU, potentially for many devices.

Need an ultra small solution, with the tag antenna integrated as on the RF37S114

Preferably, not have to be in immediate proximity to the tag while transferring data. 

Need CRC checksum for reliability.

The "Reader" would actually be writing to the tags which in turn would then need to transfer the data onto the MCU.

Hello Andreas,

Thank you for this information. Yes, I would like to know more. I have a few questions:

From the DS, it looks like the MCU needs to be up and running. In our case, we could have the MCU in sleep mode or even in shutdown mode where only an external RTC Load Switch would restore power to the MCU after a certain time or by resetting this RTC IC.

-Can the PCD wake up the system?

-Could you give me some antenna sizes required vs. communication distances?

-What does the PCD side looks like, architecturally?

-Is the RF430CL331H acting as a pass through device, IOW, data transferred reaches the MCU without having to be stored on this IC?

-Could you use a smartphone to communicate with this IC and transfer the FW load this way?

Hello Jorge,

yes the reader can wake up the system by using the VCORE signal, which is generated from the RF field. Please read the following application note for more details: https://www.ti.com/lit/pdf/sloa200.

There are some example antennas compared in Table 5 (page 11) of the following Application note: https://www.ti.com/lit/pdf/sloa217. It is actually referring to the RF430FRL152H device, but these antennas can be used for RF430CL330 as well. The communication distance also depends on the RF power of the reader side and its antenna size.

The PCD side can be any ISO14443 compatible reader with NDEF file system support. A customized closed loop system would not have any limitations (see chapter 2.1 of the FAQ document https://www.ti.com/lit/pdf/sloa244). TI also provides a reader device TRF7970A (https://www.ti.com/product/TRF7970A) and its evaluation bundle DLP-7970ABP + MSP-EXP430F5529LP.

The RF430CL331H is acting as a pass through device, but it has some buffer memory.

A smartphone can communicate to the RF430CL331H, but we have heard of file size limitations, especially on iOS.

I also want to mention, that the RF430CL331H requires some MCU control to handle the data transfer. So if you want to load a FW to an empty MCU then this MCU has no FW to control the RF430CL331H. If you want to replace FW in an MCU, then this problem does not occur.

Best regards,

Andreas.

Hello Andreas,

Thank you for the great answers.

Do you happen to know what file size limitations on iOS devices exist for an iPhone or other iOS mobile device to be able to send data to the RF430CL331H? Where can I find out more information on this topic?

Do the same file size limitations exist on Android smartphones?

Hello Jorge,

I don't know all the details, but I heard of problems in iOS for a file size >35kB. I think this was not the case for Android. But there is a general limitation for NDEF messages of 65536 bytes (NFC Forum Standard). The only workaround would be a fully customized close loop system, which does not have this limitation.

Best regards,

Andreas.

Hello Andreas,

Why am I seeing two part numbers for the same VQFN package?:

RF430CL331HIRGTR

RF430CL331HRGT

Are these identical parts?

Hello Jorge,

where did you find these two part numbers?

The TI store is providing two part numbers but for different packages (RF430CL331HIPWR for TSSOP package and RF430CL331HIRGTR for the VQFN package).

Usually the R at the end of a part number just indicates that it is packed on a reel.

Apart from that I would assume these are the same parts.

Best regards,

Andreas.

Hello Andreas,

One was from the DS itself, the other one I cannot remember now; but when searching on DigiKey, only one shows up so I'm OK with that.

Thank you,

Jorge.