INA118UB instrumentation amp woes
 

Hello,

Has anyone seen any lot problems with BB/TI INA118UB instrumentation amps?
http://focus.ti.com/docs/prod/folders/print/ina118.html

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.

INA118UB instrumentation amp woes
 

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:
Hello,

Has anyone seen any lot problems with BB/TI INA118UB instrumentation amps?
http://focus.ti.com/docs/prod/folders/print/ina118.html

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.

INA118UB instrumentation amp woes
 

"JW" wrote in message
...
It occurred to me that these could be
forgeries.

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

INA118UB instrumentation amp woes
 

JW wrote:

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.

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.

INA118UB instrumentation amp woes
 

On 26 Jul 2006 03:17:01 -0700 "Mr. Wizard" wrote in
Message id: .com:

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?

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.

I'm sure you ruled
out all other possibilities before coming to the conclusion that it is
indeed the instrument amp.

Yes.

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

cheers

I will, thanks.


JW wrote:
Hello,

Has anyone seen any lot problems with BB/TI INA118UB instrumentation amps?
http://focus.ti.com/docs/prod/folders/print/ina118.html

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.

INA118UB instrumentation amp woes
 

On Wed, 26 Jul 2006 08:55:26 -0700 "Walter Harley"
wrote in Message id:
:

"JW" wrote in message
.. .
It occurred to me that these could be
forgeries.

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


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

Thanks to all for your followups.

INA118UB instrumentation amp woes
 

On Fri, 28 Jul 2006 12:18:50 -0400 JW wrote in Message id:
:

On Wed, 26 Jul 2006 08:55:26 -0700 "Walter Harley"
wrote in Message id:
:

"JW" wrote in message
. ..
It occurred to me that these could be
forgeries.

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


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

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.

INA118UB instrumentation amp woes
 

JW wrote:
On Fri, 28 Jul 2006 12:18:50 -0400 JW wrote in Message id:
:

On Wed, 26 Jul 2006 08:55:26 -0700 "Walter Harley"
wrote in Message id:
:

"JW" wrote in message
. ..
It occurred to me that these could be
forgeries.

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


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

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.

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.