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

T

#### Tom

Jan 1, 1970
0
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.

J

#### Jim Granville

Jan 1, 1970
0
Tom said:
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.

You want the 25F serial FLASH devices, see
http://www.sst.com/news/?id=244

and also
http://www.atmel.com/dyn/products/datasheets.asp?family_id=668
-jg

J

#### Jens Hildebrandt

Jan 1, 1970
0
Tom said:
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.
http://www.st.com/stonline/books/pdf/docs/7736.pdf
2MBit SPI-Flash from ST

Jens

R

#### Reto Felix

Jan 1, 1970
0
Hi Tom
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.

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

Reto Felix

J

#### jetmarc

Jan 1, 1970
0
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

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

T

#### Tom

Jan 1, 1970
0
Use only 256 bytes per page and leave the rest blank.
You loose 3% capacity.

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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