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I know, they are technically the same, but from what I read, NAND flash chips can be controlled better like putting it into standby and waking it up in the matter of a few nanoseconds, which could be useful for recording projects that need to transfer the RAM buffer every few seconds.

I would need at least 128GB / 1TBit, so NOR flash chips are unfortunately not an option.

It would be worth it to implement a BGA package, but only if that saves more power than a micro SD card which is typically designed to be as fast as possible for the end consumer.

Also, I was not able to find out much about that, but I read that NAND flash chips have two modes: SD and SPI. Does that mean they can be connected just like a micro SD card via SPI protocol to a MCU just with the addition of more pins like chip enable, etc.?

Unfortunately, it is pretty hard to find any datasheets of bigger NAND flash chips, so maybe some people with experience on that matter can help. :)

And besides all of this, is there any other method to save data more efficiently on battery powered devices?

I apologize for any spelling/grammar errors - I'm not a native English speaker.

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There are a number of different NAND devices - The ‘usual’ is a parallel interface like ONFI like you’ll find in usb sticks, ssd etc There’s serial NAND that use a serial interface like SPI as the interface Then we get into the ‘smarter’ flash devices that have a flash controller that implements things like wear levelling and bad block management like eMMC, usb sticks, sdcard and its variants. I suspect this is what you want. eMMC will have the amount of storage you require. Effectively they are a sdcard in a bga package. I’ve not compared power consumption. You can find data on emmc from suppliers like Digikey. Kioxia is one manufacturer.

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Your 'bigger NAND chips' are essentially eMMC i.e. the memory used in smartphones. They are not exactly easy to use if you don't have their control circuitry in you CPU, however.

Also you didn't say what your transfer rate would be. In fact even the cheapest SD card will go in sleep when not addressed; a huge part of the power consumption is for the high speed data lines (the other being essentially programming power). Be careful that unmanaged NAND (raw NAND with ONFI or similar) is subject to errors and bad blocks (you have to handle them in code) while managed one (SD, eMMC).

Look in using the minimum transfer rate for your application and compare the available chips.

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  • \$\begingroup\$ About every second, the RAM buffer of about 7 kilobytes has to be transferred into the memory chip. This is a very low rate, so I assume there could be ways to use a slower communication for power saving. \$\endgroup\$
    – Krauseler
    Apr 19, 2021 at 14:10
  • \$\begingroup\$ @Krauseler You get to pick the sd card clock, so use something slow. Also try to write as much data at once and in larger powers of 2 so you don't write out half empty blocks. \$\endgroup\$
    – user1850479
    Apr 19, 2021 at 14:14

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