Unlimited write cycle memory


I need a memory which a small byte value (10 bytes) must be written to on the order of 1,000 times per day, with a life time of 5 years minimum, and retain through power cycles. The maximum time the machine will be off will be a few days, much like a pc, any longer and it does not need to retain this data.

I have heard of some battery-backed ram chips, or even IC's with the battery 'built in' and a very long life, i like the sound of this, minimum fuss.

Flash memory is no good, as i understand it they only guarantee around

100,000 writes to any particular location.

Anyone have some suggestions ? The interface is not important, we will do what we have to (microprocessor) to use it, and writing speed is also not an issue. We want relaible long-term storage and many writes.

Thanks :) Alex.


Reply to
Loading thread data ...

Sorry just to clarify the above, the memory only needs to hold the '10 bytes' at any one time, each subsequent write will overwrite the last.


Reply to

You probably want a non-volatile SRAM.

Check digikey or whoever your prefered supplier is for NV SRAM.


Reply to

Either Ramtron FRAM, or as your data is so small, use an eeprom with an algorithm to distribute the writes over several locations. The latter approach can also be designed to guard against corruption if power fails during a write.

Reply to
Mike Harrison

Look at FRAM. Ramtron/Infineon.

10^10 read/write cycles, and a predicted 45year life. It also is as fast to write as SRAM.

formatting link

To my mind, for many high endurance applications, it is the 'best' of the current offerings.

Best Wishes

Reply to
Roger Hamlett

algorithm to distribute the

As long as writes can be done per byte... use a byte for flag and append the data. First write all data, sequentially, with the flag 0. Then overwrite everything with the flag 1. Then use the flag set to 0 again.

After a power failure, go scan the memory and check what the last written flag was (where the change is). That is the wanted data.

It might be slightly better to write more than 2 flag values, but then it might not be. Also ensure that an erased block has no valid flag values.

For a 32 megabyte flash, the life would expand a factor of 3 million from the number for the device.


Reply to

u must use serial eeprom 24c01 OR 24c02

they offer unlimited read/write cycles, its fit to your application the last for more then 7to 9 years...

i have been using one since last 2 n half year or so....

they r the best for u

they r compact (8pin) to improve circuit portability and are reliable....

they can retain data with no time constrains......

(personal experience - once i turned on my circuit after 2 or 3 months and the data was still there...)

this chip is gr8 man ....

go on and do wat u wanted to....

Reply to

algorithm to distribute the

guard against corruption

That's the most cost effective answer.

Many Eeproms are now rated for one million writes IIRC.

A 24C01 used that way would fit the bill.


Reply to
Pooh Bear

Re: "Unlimited write cycle memory"

As a useless observation... All memory has unlimited write cycles. Question is, when do the subsequent read cycles stop working?

I'm thinking of the infamous data sheet from a-long-time-ago provided on April 1 for the new WOM device. I should post a link but I'm too lazy* and someone else will probably step up.

Ah, well, it is Friday night.

  • (rethinking) How hard is Google? Here is one link...
    formatting link

Not a great scan, but others can google for a better one.

Reply to

Finally some1 who writes understandable w/o 2 many letters.

ciao Ban
Bordighera, Italy
Reply to

Not true. Read the datasheet. Write endurance for eeproms is typically 100K to

1M writes.
Reply to
Mike Harrison

Thanks Everyone for your suggestions.

I have gone with some NV SRAM, specifically; BQ4011,

formatting link

256k, 10 year 'off' life (in reality many more years because of a very low 'off' time) Fast and unlimited write cycles. Also fairly cheap at about 5gbp a piece. (farnells,uk)


Reply to

ElectronDepot website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.