How to sniff fake TDA7293s ?

[jondoe]

I'm in a little dilemma here...
I want to build a simple but kinda ok 5.1 system with these TDA's.
At my local shop i can get 1 TDA7293 for 9.65 $.
I found another one that has them for about 7.
I also found modules ready to run with TDA7294 for cca. 11 $
Now, i found these 7293's for about 4.1 $ that i can get delivered by mail.

Q:
How can i tell which one's are fake ?
The reason: lots of stuff here are cheap fake junk.
(about 90% of parts are fake, from my pov, either don't have the advertised capabilities or they tend to blow)

The expensive one's are, ... well ...., expensive....
(i kinda need 13 of them)
The cheap ones are, ... well ...., cheap....

From my POV, neither are real, and no shop here can guarantee they are true ST brand. I did heard that the store selling the 4.1$/pc is quite big and self respected. But can i really trust it ?

Can some analisys be made on the price ?
Or do i get one, break it to pieces an see it's guts ?
But then, how does one's stomach look like?

HELP !!!

[gatedriver]

4,10 USD is really cheap.
one of the cheapest shops here has them for 5,25 EUR. I recently bought four and they don't look like fakes. I haven't used them yet.

Why don't you buy just one or two of the cheap ones and see if they're fake..
You can find out if they're fakes if they don't meet datasheet specs and/or have fake packages. See the various transistor fake threads with pictures for reference.
Of course you need a genuine part to compare against if you want visual inspection of the die.. but many fakes have white glue on the die or other unprofessional artefacts.

some manufacturers quote prices on their web site so you could check against that.

[aditaquil]

Hi, for me if the TDA not show the ST logos, and printed bad that the fake one.
In my near distrib its cost only US$ 3.1, close to LM3886 price.

[jondoe]

I've seen all kind of prints... all wearing the ST logo...
Some with white paint, some by engraving ...
Also the metal backplates i've seen, some were shiny stainless stell like, other were mate, more like aluminium and with the consistency of compressed steel-aluminium chips (more like the leftovers from drilling - sory, don't know the english word for this).
In other words, seen all kinds of packages...

I have built in the past a stereo bridged amp using 4 of those engraved ones, and it rocks. Long term shorts on the output at full power -> nothing happened, it was perfectly happy (other amps i had would just blow fuses or worse). I lend it to some idiot friend of mine who somehow plugged a 35 volt dc powersource to it's outputs. Guess what ? Nothing happened. And it sounds good too...
The bad thing, the source for these is long gone...

So what do you say, how does yours look like ?

[eborgard]

Package and info on the package depends on the company (and line) that made the encapsulation of the silicon die.

So , there are NO fakes, just different machines/companies that put the silicon in a plastic package. And there should be no difference in quality at the end.

[jondoe]

I was under the impression that ST was packaging these babies.
If not, i'm in deep LULUland.

[eborgard]

I believe so: the package was designed by ST, is mostly used by ST (although there are a few other companies designing chips for this package type), and ST has inhouse assembly facilities....