Looking for large serial EEPROM or FLASH like Atmel's DataFlash

Jun 24, 2004 7 Replies
T

I'm looking for a large serial EEPROM or FLASH chip that comes in a small package and uses a serial interface. I need something in the range of 1024 kbit - 2048 kbit in an 8-SOIC or smaller package, and it needs to be as cheap as possible. :)



So far I've only found I2C EEPROMs like the 24C512, but these only seem to go up to 512 kbit or 1024 kbit, and they also get very expensive when you go up to that size. Atmel has their "DataFlash" series which are fairly inexpensive, and they fit my needs in terms of package size and capacity, but the stupid



264-byte page size and lack of linear addressing makes them almost unusable in my application. I just don't have enough CPU cycles left over to divide by 264 every time I need to seek to a new location.

Does anyone know of any other chips out there that have the same cost-per-bit as the DataFlash and also have the same ease-of-use as the 24Cxx series?


--Tom.


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J

You want the 25F serial FLASH devices, see

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and also

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-jg

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F

maybe here..

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"Tom" a écrit dans le message de news:TBrCc.864742$oR5.460604@pd7tw3no...

cheap

go

up

inexpensive,

stupid

unusable in

264

cost-per-bit

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J

How about this one (M25P20):

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2MBit SPI-Flash from ST

Jens

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R

Hi Tom

cheap

go

up

inexpensive,

stupid

unusable in

264

What is when You only use 256 byte per page? We are using the remining 8 byte for a checksum.

Reto Felix

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J

Use only 256 bytes per page and leave the rest blank. You loose 3% capacity.

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M

SGS-Thomson do some similar devices, I think they have sensible page sizes

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T

I had this idea as well, but it doesn't work when you're doing a sequential read. The sequential read doesn't automatically skip past the 8 unused bytes, so you will get "gaps" of 8 bytes at the end of every page. So now I would have to keep track of the current offset within a page, and then remember to skip past the 8 unused bytes at the end of every page, and also clock the SPI at a faster speed (I'd have to change the CPU crystal here) in order to quickly skip past the 8 extra bytes and still get the next useful data byte in time for when I need it. This is just more hassle than its worth.

As for the other suggestions that people have mentioned, here's what I've found so far:

SST: Looks like a good choice, the SST25VF010 is 1Mbit and lists for $1.32 at future-active.com and SST also has 2, 4, and 8 Mbit versions.

Atmel's 25Fxxx series: Looks OK, and the price for a 25F1024 is also $1.32 at digikey.com and they also have the 2 Mbit AT24F2048 for $1.87 but there's nothing bigger than 2 Mbit in the same family.

Ramtron: The biggest device they have is only 256 Kbit.

STMicroelectronics: Ok, first of all I HATE their website but the M25P10 looks like a good device and Digikey has them for $1.37, they also have 2 Mbit, 4 Mbit and 8 Mbit versions for $1.76 and $2.10 respectively.

Thanks for all the suggestions and keep them coming if you know of any companies that make serial EEPROM or FLASH!

--Tom.

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