LM2575 CODE MARK

Hi people. I'm in doubt about the provenance of a lot of LM2575 IC's that have reached the company. All of them are marked with the code "(National Logo) JM21RP LM2575T -5.0 p +." How can I check if code is true ess and ensure the provenance of the component?

My source of information is this page:

http://focus.ti.com/quality/docs/gencontent.tsp?templateId=5909&navigationId=12626&contentId=153966#assembly.

However it does not clarify some information:

• U = Wafer Fab Code
• Z = Assembly Plant Code
• TT = 2-Digit D/Run

What are the values ​​that these markings can take.

Perhaps there is some document that clarify it but not found.

I would like your help to make sure the code above is true or it is fake.

Tank you!