OPA4134: DC Offset spec issue

Hello BR,

The OPA4134 has a maximum specified voltage offset of +/-2 mV, at TA = 25C . With the noise gain set to +101 V/V, the output referred  voltage offset contribution from the maximum input offset would be 101(+/-2 mV), or +/-202 mV. Input bias current contributes to the output referred voltage offset as does CMRR, PSRR, etc, but their contribution would be very small compared to the input voltage offset. Thus, the 381 mV that you measured is high compared to the +/-202 mV maximum. TI would have tested the OPA4134 device at both probe and final tests to make sure that it meets the specified maximum input offset. Verify that the OPA4134 devices you have were obtained either from TI directly, or one of TI's authorized distributors. If they were obtained elsewhere they may not be actual OPA4134 product.

I am not finding the Offset Voltage Production Distribution you reference on Page 20, but I do find Figure 21, Offset Voltage Production Distribution, in the datasheet. The graph provides information regarding the input voltage offset distribution obtained from testing many OPAx134 devices. The distribution shown is that of a normal, or Gaussian distribution. It reveals that the OPAx134 input voltage offset is centered at 0 uV, with most devices having an offset close to 0 uV. Then, as the offset moves away from 0 uV in either direction less and less devices have a higher offset magnitude. Very few devices have an offset as high  as the +/-2 mV maximum.

Regards, Thomas

Precision Amplifiers Applications Engineering

Hello!

Thank you for your reply.

I understood your comment, How I request analysis fake or not this parts from T.I? If Can T.I analysis How much cost and How long report time?

if analysis result Fake, How to many have Fake parts In market?

Please advice.

Rigards, Richard.

Hi Richard,

Where did you get these OPA4134 parts from? Did you order them directly from TI.com? You may order samples of this device from our online store and test them:

http://www.ti.com/product/OPA4134/samplebuy

-Tamara

Hello Richard,

Unfortunately, TI cannot reveal product marking information details because product counterfeiters can use such information to mark their counterfeit products. It is common for counterfeit Op amps marked with a particular model number to function as an Op amp, but then not to achieve the electrical specifications of the authentic product. If your OPA4134 product was purchased directly from TI, or one of TI's authorized distributors, then it should comply with the electrical performances listed in the Op amp's datasheet Electrical Characteristics table.

I would take Tamara's advice and order some OPA4134 samples from TI's online store and test them. When tested they should provide offset performance that complies with the datasheet specifications.

Regards, Thomas

Precision Amplifiers Applications Engineering

Hello, Thomas,

We purchased fron from third party supplier marked on OPAMP (93FK5XK). +19year producte date, and I requested another + 19year Product date samples also all have mix bad part.

The samples marked 93FK5XK on OPA4134 alone at 25 dgree DC offset test  resullt as below.

1. 24mV

2. 293mV

3. 111mV

4. 281mV

5. 52mV

6.314mV