Questions NOR flash memory

[tiago1986]

manufacturers of NOR flash memory chips say that they retain data for up to 20 years but I am doubtful if it is possible to increase this retention estimate a lot? I write the firmware only once in the flash memory and store it

 

I don't want to lose retention

[David Hess]

My solution for that in the past has been to maintain a second copy so that the stored data can be periodically refreshed.

[mikerj]

The cooler you can keep the device the better the retention will be.

[DavidAlfa]

20 years is usually for NOR EEPROM. NOR flash often has >100 years data retention.
Anyways, you can find arcade eeproms perfectly readable after >35 years.

[tiago1986]

Here are the photos of the board and chips

[ataradov]

20 years is a very conservative estimation over the full voltage and temperature range. If your device would be stored and working at room temperatures, then you should not worry about it, it will be fine for a long time.

At the same time, if you are really worried, you need to implement a refresh procedure that reads and writes back the entire flash once every few years.

[tiago1986]

if I use to power this cartridge card 1x a year will the data be released more quickly in these NOR flash memories?

[ataradov]

Storing in a non powered state is generally preferable for longevity.

But again, you are overthinking it. The retention numbers are highly conservative. 20 years is basically just a "meaningful lifetime of a consumer product". Manufacturers don't want to commit to more time than they need to, and 20 years is the time frame that removes the market pressure.

[tiago1986]

What are the main manufacturers of NOR flash and flash memories? I intend to contact them

if i don't use these cartridges 1x a year will they live 20 years of data retention in flash memory?

[ataradov]

They will live for 20 years no matter what you do to them (operate continuously or just once) as long as you won't exceed the maximum operating conditions. 20 years is a guaranteed time for normal use.

There are lots of manufactures, but I seriously doubt you will get a better from them. ST is one, as shown on your picture. Just go to the Mouser or digikey and search for NOR flash and you will get a complete list.

Why are you so concerned with this? What is your use case?

Oh, I looked at your old posts. You seem to overthink things a lot. Relax, you will spend your entire life thinking of how to preserve stuff that you will never actually enjoy using it.

[tiago1986]

I just want to preserve the retention of data in the NOR M29W640FT flash memory and not have an expectation of failure on it but surpass 20 years to not put my electronics in the trash

[ataradov]

Again, don't worry about it. That 20 years retention time is for when you are running it at 85 C 24/7.

Your cartridge will last longer that you will.

[tiago1986]

the temperature here varies from 30 to 33ºC and I will use 1x a year? I have two cartridges the same one I use constantly and the other saved and both use this NOR flash memory ST M29W640FT  where the OS firmware is saved

[ataradov]

What do you want from us? The manufacturer guarantees 20 years of retention in that scenario.

I tell you that in reality it will be much longer. Relax.

[tiago1986]

I did not find any information about the manufacturer of the NOR ST M29W640FT flash chip for 20 years at 85 C 24 hours a day, 7 days a week

where did you see this information?

[ataradov]

In the datasheet for the device is says that minimum  data retention time is 20 years. And unless otherwise specified, the parameter applies to the whole range of normal operating conditions. And maximum nominal operating temperature for the device is 85 C.

[tiago1986]

Where do I find this datasheet?

20 years is for 85ºC every day? for 33ºC what would be the correct calculation?

[ataradov]

Google "M29W640FT". How else do you find datasheets? Here it is http://www.farnell.com/datasheets/40281.pdf

20 years is the industry standard value, literally nobody cares about longer longevity, except for you, apparently. The actual value is probably way over 100 years.

It will be even longer for lower temperature. There is no point in discussing the exact numbers, they are high enough that other factors will start to play bigger role. The soldering and other mechanical parameters are not guaranteed for that long.

[tiago1986]

100 years is a long time of data retention I did not have this information I just know that the temperature in my house is 33ºC but I thought that regardless of temperature and humidity, data is automatically erased in 20 years

in the pictures of the card that I posted have any other memory chips?

[ataradov]

Why would it erase after 20 years automatically? This makes no sense. All memory devices degrade over time. The manufacturer guarantees that the data will be retained for at least 20 years under the worst case operating conditions.  I mean in theory it has full rights to just erase after 20 years, but that is not what happens in practice.

MAX 2 CPLD is a programmable device. I don't see any longevity specifications in the datasheet, but it would be also at least 20 years.

20 years is a long time, are you sure the rest of the stuff you plug in your cartridge into will last that long? Are you accounting for wear on the card edge connector? It may not last 20 years of continuous use.

And that CIC chip substitution seems to be some sort of PIC microcontroller, so it is also a programmable device.

And that Ramtron chip is also technically a non-volatile memory, but I'm guessing it gets reloaded on each power up anyway. And it has 45 years of retention specified.

So apart from a voltage regulator all chips are programmable.

[tiago1986]

I read the datasheet thanks but I didn't find a reference for data retention in flash memory NOR model ST M29W640FT 70N6 H for 20 years at 85ºC

[ataradov]

Table 8 in the datasheet I linked specifies the retention time.

[tiago1986]

table 8 it doesn’t refer to what temperature

[ataradov]

That's how datasheets work. All parameters apply to a full operating range unless otherwise specified. That's why you see temperature specified for the typical values.

Table 11 specifies operating temperature range, which is a standard commercial range of -40 C to 85 C.

[tiago1986]

Thanks for the answer now I understood and I was surprised by the condition of this NOR flash memory to retain data for 20 at a temperature of 85ºC this memory is very resistant to heat

this datasheet is from the numonyx brand and my NOR flash memory is from the ST brand, is the datasheet the same for the two brands of M29W640FT 70N6 H?

during the use of the cartridge in the SNES at which maximum temperature does the ST M29W640FT 70N6 H flash chip reach?