OPA2227: new parts with very high input bias current

Hello Uwe,

Valid OPA2227U product is fully dc tested in production and the input bias current must not be greater than the +/-10 nA maximum listed in the Electrical Characteristics table. An input current of 83 nA would indicate something is out of line; possibly the device had been ESD damaged, there's PC board flux contamination adding a leakage current component to the normal bias current, or its not legitimate OPA2227U product. If you are purchasing the OPA2227U product from an authorized TI distributor it should be valid TI product.

I don't have direct access to lot code information, but I am able to check the OPA2227U topside marking information. The 3rd line is the date code. It should have 6 alphanumeric characters. Some date codes you have listed only have 5, which do not conform to our marking requirements. Also, there should be a separate alpha character towards the right end of the second line. Below, I show an OPA2227U image I pulled from Google images. It provides an example of the correct package topside marking formats.

Regards, Thomas

Precision Amplifiers Applications Engineering

Hello Thomas,

thank you for your fast response.
To clarify the problem we have attached some images from our used OPA2777U with different codes.
The following things were noticeable to us:
The codes always have 5 characters and not as you have highlighted "It should have 6 alphanumeric characters.".

The parts with the code "19ZM6" are the bad parts with the high input bias current. (we have not onlyone part, in this modul production ALL parts have this error!!!, more than 600 parts.)

We can see differences in the laser print, but don't know if it is importent (the wrong parts have the pin 1 sign as a deepening in the housing, all other parts have it laser printed).

We can also exclude problems with the ESD handling, because the production is fully ESD certified and verified. PC board flux contamination can also be excluded. After exchanging the parts with the parts from our stock with the "good" date codes all works fine and the input current is below 1 nA.

Our only guess is the delivery of not legitimated OPA2227U products we have to check with our assembly company. That's why it is important for us to know, if the date code "19ZM6" (see image) is a valid TI code.

Thank you very much for your support,

Best regards, Uwe

Sorry, I don't know how to attach pictures. Is it possible to mail it to you? the problem date codes are: 19ZM6, the good ones are: 31ZB8, 57AP45, 7623H, 8BER8

Hello Uwe,

The OPA2227U marking documentation indicates that the pin1 identifier is ink marked, and additionally identified by a broader bevel on the end of the package adjacent to pin 1. See the Plastic Small Outline drawing for the D (R-PDSO-G8) package near the end of the OPA2227 datasheet pages. I don't think that the pin 1 dimple has been used for this product for many years.

Product markings have changed across the decades and it may be the 19ZM6 devices are very old and used a different marking system. However, if that is the case they would have been out of warranty long ago. On the other hand, since all of these devices are failing the input current specification by a large amount their origin may be suspect.

I don't have access to lot code information because TI tightly controls its use. There was a TI E2E blog some years ago that provides information about dealing with suspect material. Please see this:

Regards, Thomas

Precision Amplifiers Applicaitons Engineering

Hello Thomas,
thank you for your fast reply. So we will start to analyze the supply chain of our module manufacturer. I also believe that the origin of this "OPA2227" parts may be suspect.

Thank you for your support, have a nice day...
Best regards, Uwe