Hello,

One can easily find information about the differences between SLC, MLC and TLC, but actually how do you know if a NAND chip is a SLC, MLC or TLC ?

As datasheets/specifications of NAND chips seem sometime difficult/impossible to find, I assume the way to go is knowing the general rules used by the producers to name their chips.

For Toshiba, I assume that TLC is when you have a "T" at the second position ; eg. TT58G2JAJA
because on the page 3 of this document http://www.triton-prog.ru/Dnl/Nand_Toshiba_NEW.pdf, C is for single chip and H for multi-chip. Can someone confirm this ?

These days you cant really understand what chip you dealing with MLC or TLC until you read it (SLC is past).
More to say, in ~30% of all cases you cant even know who's vendor of chip until you read its ID, because in the era of TLC chips there's such a huge amount of defective chips at factory, that vendors don't get rid of them (in ideal world they have to), but resell it to small "companies" who change the label or make their own.
And you don't really need to care about these SLC/MLC/TLC things because each chip-off tool has it's own NAND chip database.
Every "official" chip has company name/logo on the package (in 100% of cases) - Toshiba, Sandisk, Samsung, Hynix, Micron, Intel.
TT58G2JAJA is a chip that didn't pass QC successfully and was sold as noname one in a huge amount (shame on you Toshiba!).
You can see on the picture below it has same ID as normal chips, and can be recovered as well. It just has more bit errors, bad columns and bad blocks.

_________________
VISUAL NAND RECONSTRUCTOR. A big revolution in chip-off data recovery

Thank you Sasha.

The TT58G2JAJA chip came in my case from a Sony USM-X series:
http://www.sony.net/Products/Media/Micr ... cts/usm-x/
Sony isn't really what we call a small company ...

And the sticks came with a 5-years warranty.
Well, this is also marketing, but Sony is a renowned brand and if the chips were poor quality, they probably wouldn't take the risk to see too many coming back in the next 5 years.

From what I read, the same chip was however also used by Kingston DataTraveler, probably on the lower segment with two years warranty (as for the DataTraveler).

I purchased several Sony USM-X series in the context of a flash stick repair.
The one with a 8 GB stick was branded Toshiba.
The 32 GB ones were "no names", but seemed labeled according Toshiba's naming conventions.

There could be other reasons to "no-name" chips. Toshiba may sell its technology under license, or sell/rent older some production chains to finance new ones, a.s.o.
But maybe are you more informed than me.

Are you sure that the second "T" on a Toshiba model is not for "TLC".
It seem that this second letter was codified as the NAND type in the past (see the document that I attached in the original post).
Maybe, with enough "TT..." chips it would be possible to check if all are TLC or not.

The chip that you highlighted is a TT17G2JAJA, not a TT58G2JAJA.

When you read a chip, how are you sure that you don't damage it with overvoltage?
So, how do you know that the chip doesn't work at 1.8V, especially when the chip is not in databases?

"Sony is a renowned brand and if the chips were poor quality, they probably wouldn't take the risk to see too many coming back in the next 5 years."
"Same chip was however also used by Kingston DataTraveler, probably on the lower segment with two years warranty (as for the DataTraveler)"
As you said, they just give away this warranty because they know that nobody will come and bring 10$ device to warranty exchange after 1 yr usage.

"There could be other reasons to "no-name" chips"
Nope

"The chip that you highlighted is a TT17G2JAJA, not a TT58G2JAJA"
Same

"Are you sure that the second "T" on a Toshiba model is not for "TLC"
Could be. Then "D", "T", "U", "H" also stand for TLC. And pretty much half of alphabet
All the chips on the pic made by Toshiba

_________________
VISUAL NAND RECONSTRUCTOR. A big revolution in chip-off data recovery

You have the PCBs. Measure the voltages across the supply bypass capacitors adjacent to the NANDs.

_________________
A backup a day keeps DR away.

There's even faster solution, just set initial voltage as 1.8V, power up memory and have a look in dump.
If it looks OK (you can see at least some data in Bitmap/Hex), then chip works fine, stay at 1.8V.
If chip/reader hangs or show blank dump then it's too low power, go for 3.3V.
Almost all raw NANDs used in flash devices support both standards 1.8/3.3V. However, many old smartphone chips work under 1.8V

_________________
VISUAL NAND RECONSTRUCTOR. A big revolution in chip-off data recovery

Thank you Sacha. I learned a lot from your messages and the screenshots you uploaded.