Currently we do not have a 16Kbit FRAM with its own unique read only ID. I have passed the information to our team and RAM BU and they will check on this. Let me get back to you on your other queries in some time.
Please find our comments below.
1) The commands/opcodes of the Excelon devices are compatible with the existing FRAM memories.
2) You have to follow our reflow procedure as mentioned on our website. You can be then 100 % sure that the value is correct as it is tested.
3) You can check our website to buy the excelon parts if you are having difficulties in obtaining the parts or samples.
We do have a plan of incorporating a unique read only ID to smaller FRAM memories to. For more details please contact your nearest Cypress representative or you can create a Customer Marketing case with us.
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Putting additional comments on your query in 2).
2) It’s recommended to append the checksum to the 7-byte user-defined serial number. However, a similar verification isn’t provided for unique ID. Is it? Datasheets state that the unique ID registers are guaranteed to retain data integrity of up to three cycles of the standard reflow soldering. Let’s assume that the FRAM device is exposed to unacceptably high temperatures or other unallowed conditions during PCB assembly. How can users be sure that a virtually random value is correct without checking it?
Response - The 8-byte unique ID is programmed at Cypress factory and unique to each device. UID is a read only register, hence its content can't be altered in the field. If the unique ID happened to corrupt due to any circumstance, it can't be determined in the user mode. In case if the F-RAM happens to expose to a very high temp (beyond recommended reflow temp profile) and if that impacts the unique ID registers, in that case even the 8th byte as checksum won't help to detect reliably because the checksum byte will have equal chance to corrupt itself. Hence, in case if the soldering flow has susceptibility to violate std temp profile than JEDEC recommended, you can build some reliable workaround in FRAM by using its special sector (256 byte) which also guarantees at least three re-flow cycles.
1- Read unique ID at normal temp
2- Create a copy of the unique ID by writing to special sector. You can then calculate the checksum and secure that as well in the special sector.
3- Read unique ID register after the re-flow, calculate the checksum and compare with the stored checksum in SS. If the checksum match found, means unique ID remains intact. If mismatched you can compare the UID with stored 8-byte in SS. This methods only adds redundancy, hence reduces the chance of occurrence.
I will keep in mind the Excelon devices for our current and further products.
For smaller FRAM memories, MSP430 FRAM microcontrollers are also available from Texas Instruments.
However, this solution requires separate programs for MSP430 microcontrollers.
On the other hand, a custom protocol is possible for data exchange.
Thank you for your response.
As I understand, you suggest to read the unique ID and create a copy of it with corresponding checksum before reflow.
This approach demands additional procedures because we usually start to read/write data after assembly.
I will think over your offer.