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INA118UB instrumentation amp woes

Hello,

Has anyone seen any lot problems with BB/TI INA118UB instrumentation amps?

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We've just received 100 of these devices that we use on the front end of a A/D and they all appear to be bad. They are marked INA118UB with lot code

0425. We run them from +5VDC power supply, and regardless of their input, their output is pegged at 4.2VDC. It occurred to me that these could be forgeries.

Also, they were purchased from Part Miner and it's beginning to look like they may be putting up a fight with regards to our returning them - has anyone had problems with this sort of thing with them?

Thanks.

Reply to
JW
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You pose a good point about knock off chips. I'll keep that one in mind whenever I purchase parts through part miner.

Is this a new circuit you are using the IAMP in? I'm sure you ruled out all other possibilities before coming to the conclusion that it is indeed the instrument amp.

Please, post how it goes. I'm interested in knowing if the part houses are passing along forgeries.

cheers

JW wrote:

Reply to
Mr. Wizard

Send one or two to TI - I'm sure they'll be able to tell you pretty quickly.

Reply to
Walter Harley

TI's authorized distributors are Arrow, Avnet, Mouser, Digikey, and Newark. I would first ask where Part Miner aquired these because there is an issue with counterfeit parts in the industry...or so I hear.

Reply to
Kingcosmos

Nope. We just built 500 boards - 400 worked or had other issues, The other 100 have bad amps. All the working boards have a different lot code. The two sets of lots were purchased from different vendors.

Yes.

I will, thanks.

Reply to
JW

Good point, I'll see if I can contact someone there...

Thanks to all for your followups.

Reply to
JW

Well, it looks like they're forgeries. This is from the support engineer at TI, after I supplied them with a picture of the markings on the chip:

"I would say that the parts were not manufactured by Texas Instruments. We acquired Burr Brown in 2001 and the top side markings *if* correct would imply a date in 2004. The top side marking standard would have been switched over to TI's 5 or 7 digit date code rather than 4 at a year and definitely by 2004.

It is possible that Part Miner procured the INA118's from our authorized distributors but they will have to be able to show the paper work to prove that they acquired them from such authorized channels. We can guarantee how the parts are stored and shipped when they are sold by our authorized distributors: Arrow, Avnet, Mouser, Digikey, and Newark; however, when parts are obtained on the grey market then all bets are off."

Another reason not to use unauthorized suppliers, and to stay away from Part Miner.

Reply to
JW

Thank you for posting a follow-up. If Part Miner is unwilling to verify their sources then they will definitely go on my no buy list.

Reply to
Mr. Wizard

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