Finding EEPROMS suitable for HATs

Question

I'm working through the HAT design guide to work out what kind of EEPROMs I can use.

To quote it:

• 24Cxx type 3.3V I2C EEPROM must be used (some types are 5V only, do not use these).
• The EEPROM must be of the 16-bit addressable type (do not use ones with 8-bit addressing)
• Do not use 'paged' type EEPROMs where the I2C lower address bit(s) select the EEPROM page.
• Only required to support 100kHz I2C mode.
• Devices that perform I2C clock stretching are not supported.
• Write protect pin must be supported and protect the entire device memory.

I would like to clarify a few things:

1. Where it says the type "24Cxx" must be used: if an EEPROM has the prefix 24C, does this mean it might still be 5v only? And if it has that prefix, does that still mean it might not be 16-bit addressable, might be paged, might perform clock stretching, and might not have a WP pin that protects the entire memory?
2. To save a lot of work, is there a list of potentially suitable EEPROMs?

Answer 1

Download a datasheet from a manufacturer which is available in your country. E.g. here's one from Microchip. Go to the "Device selection table" section and look for devices with the right parameters:

• voltage range 1.7-5.5V or 2.5-5.5V (not 4.5-5.5V)
• package with WP pin and "Entire array" protection
• density 32 to 1024 kbit (smaller densities are not 16-bit addressable)

You can apply essentially the same filters to large IC shopping websites, e.g. Mouser

A list of all compatible parts from all manufacturers would include literally hundreds of devices.

Answer 2

Don't know about a list but I used this part from DigiKey: CAT24C32YI-GT3, part #CAT24C32YI-GT3OSCT-ND. I was able to program it...and then read it.

Answer 3

I use FRAM devices,non-volatile ferroelectric memory, such as the FM25L256B-G. They are available in I2C and SPI interfaces. They do not lose data when powered down, almost unlimited read/write cycles, fast and no delay when writing or page or segment boundaries. Use it like RAM, the big difference it remembers when the power goes out. You can use the EEPROM drivers if you want, just remove the delays. Many are good for 3.5 or 5 Volts so no level translator. I2C units are available for less then $1.00 from my favorite china supplier. Several have the same pinout as EEPROMs.