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Original question:

TL072: TL072CDR Current issue

TL072: current draw from -V

guido cusani
Prodigy 10 points
Part Number: TL072

Tool/software:

Dear TI,

I noticed a similar behavior on our production including TI TL072CPWR: 

  • Quiescent current draw from +15V was ~4mA and didn't change for batches with new IC deliveries
  • Quiescent current draw from -15V halved from ~4mA to ~-2mA for batches with new IC deliveries

I agree "The guaranteed datasheet limits" may have not changed and that TL072 is a TL072H now, but the umbalanced draw worries me, and should worry TI, to be honest 

I attach a picture of the ICs (one old deliveryand one new delivery) because the markings are slightly different and may help to identify the issue.

Best regards

  • 0
    TI__Guru 70331 points

    Hi Cusani, 

    guido cusani said:
    • Quiescent current draw from +15V was ~4mA and didn't change for batches with new IC deliveries
    • Quiescent current draw from -15V halved from ~4mA to ~-2mA for batches with new IC deliveries

    There are PCN issued in TL072 due to FAB change, see the link below. 

    https://mm.digikey.com/Volume0/opasdata/d220001/medias/docus/5488/PCN20230627002.1.pdf

    What you observed are both old and new FABs are being sold currently from inventory. These op amps are equivalent op amps, except the new FAB will draw lower Iq current than the old FAB. There may be some other differences between these op amps due to the FAB change. I suggest that you are checking it out, and validate your existing design. If there are any functional issues, I can suggest modifications to improve the performance.   

    Some designer may use Iq current nominal range to detect DUT's operational state. If this is the case, the detection level may need to be modified. Once the old inventory is depleted, you will only receive the op amp manufactured from the new FAB. TL072H is the part number that is manufactured via the new FAB process, which it has lower Iq current specification. 

    If you have other questions, please let me know. 

    Best,

    Raymond 

  • 0 in reply to Raymond Zhang1
    Prodigy 10 points

    Hello Raymond,

    Thanks for your reply.

    I looked at that before posting, as someone else already pointed it out.

    I find astonishing the statement "These op amps are equivalent op amps, except the new FAB will draw lower Iq current than the old FAB", to be honest, because, if drawing different currents, they are NOT equivalent in any meaningful sense of the word.

    I found not modifyng the datasheet to include the information about the amplifier Typ. current drawing very sloppy by TI standards since it is now almost 0,.5mA or 33% less than stated.

    I, finally, find very strange amplifiers are drawing different quiescent currents from + rail and - rail because a fabrication process has changed.

    Best regards

  • 0 in reply to guido cusani
    TI__Guru 70331 points

    Hi Cusani, 

    When a product is going through a FAB change, certain product specification may be altered. As in this case, the circuit is redesigned and Si-die size is reduced (even though it is kept in the same design of the previous product). For instance, op amp's BW is increased and open loop output impedance is changed etc. These are the side effects when a product is going through FAB change. 

    I understand your frustration. TL072 is a general purpose op amp. When Si-die size is reduced, Iq is typically reduced as well. The lower Iq in any product is typically desired. If you are using the nominal Iq current as a part of design feature, I can understand why a circuit may have issues. 

    We can help you to modify a circuit, if you have issues with the existing design. The PCN and FAB changes are final, and every semi-technology product has to go through a similar phase over a life of product. I agreed that we should have documented these changes in the datasheet more specifically. 

    If you have other questions, please let us know. 

    Best,

    Raymond 

  • 0 in reply to guido cusani
    Guru 311370 points

    The TL072 does not have a ground pin, so all the quiescent current that flows into VCC+ must flow out of VCC−. If the two values are not equal, then there is a load current, or some current is flowing through the input ESD clamping diodes. The latter case would be a problem, so please check if the input voltages are outside the power rails.