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TL072: TL072CDR

Tsutomu Matsumura
Prodigy 15 points
Part Number: TL072

Tool/software:

Our customer is experiencing issues with the parts. After reviewing the details, your engineer confirmed that our customer had been using older material from a different fab, which was functioning properly. However, the parts from the new location that we purchased this time are having issues due to slight variations in the new fab, although the device remains within spec.

Your engineer mentioned that the application may have been fine-tuned for the older device and suggested raising the issue here to receive guidance on resolving it.

We have submitted all necessary information, including waveform data, through the production return page (CPR251123565).

Could you please advise on how to resolve the issue with the parts from the new location?

Thank you for your assistance.

  • 0
    TI__Guru* 77061 points

    Hi Tsutomu-san,

    Tsutomu Matsumura said:
    Could you please advise on how to resolve the issue with the parts from the new location?

    Yes, the post-PCN (new FAB) TL072 has slightly high BW and will need to compensate slightly different from the pre-PCN product. 

    If you send me the schematic, I will take a look and compensate the op amp accordingly. 

    If you do not want to post the schematic in the E2E open forum, please post a "friendship" request over the E2E. Once we are able to establish the private communication, you may send it over for a review. 

    Tsutomu Matsumura said:
    through the production return page (CPR251123565).

    I do not have visibility in the above document, which is designed for customer service. I am working in the product's application engineering, and do not talk the customer service people in general. 

    If you have other questions, please let me know. 

    Best,

    Raymond

  • 0 in reply to Raymond Zhang1
    Prodigy 15 points

    Hello Raymond, Thank you for your quick response. They mentioned that they cannot change their schematic in the near future, so they have requested the following information: 1) What are the specific differences in specifications between the old and new parts? 2) If the issue in this application is due to subtle specification differences (within the official specs) noted in 1), they would like to select a device that meets the required specifications. Do you have any recommendations for backward compatible products, if available—such as TL072A or TL072H?

  • 0 in reply to Tsutomu Matsumura
    TI__Guru* 77061 points

    Hi Tsutomu-san,

    Tsutomu Matsumura said:
    Do you have any recommendations for backward compatible products, if available—such as TL072A or TL072H?

    There is no backward compatible product in the series, unless you change the op amp part number. The post-PCN or RFAB process has activated and the old FAB is being shut down. If any small modification is not possible, I do not have a suggestion for the matter. The small change that I refer to may be as simple as change a capacitor value in your circuit, which is a part of op amp compensation loop. 

    When FAB is changed in an op amp, certain things will change due to process differences. This is very common in the manufacture process of the semi-technology, even though op amp's design remains the same or near identical. In this case, the GBW of the post-PCN is increased from 3MHz to approx. 5.25MHz. Although the open loop output impedance did not change significantly in the post-PCN design in TL072x, the increased BW will crease some issues for certain op amp configuration, where phase margin will be further reduced for some customer, which it lowers the loop stability of a design. This instability behavior is especially sensitive to certain marginal design op amps, and proper op amp compensation is needed. 

    Without looking at your schematic, it is difficult to say what is the issue. My guess is that the post-PCN may exhibit instability issues that resulting slight oscillatory effect, draw more current, poorer performance in handling certain transient behaviors etc., 

    If you are able to send me the schematic via Private E2E messaging system, I may be able to suggest a solution for the change or compensation. 

    If you have other questions, please let me know. 

    Best,

    Raymond