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TLV773: TLV773 Quiescent current issue

Damon(Shenzhen) Luo
Prodigy 70 points
Part Number: TLV773

Tool/software:

HI TEAM,

Our customer had conducted an experiment under the datasheet condition and the test result of Quiescent current is around 130uA, which is much higher than the typical value (80uA). I also conduct a test by myself, and the test result is 138.9uA. The test environment is shown in figure below by using a digital multimeter in series with the DC Input and Vin.

1: Can you conduct the experiment on your EVM and send me the test result? Thanks!

Damon

  • 0
    TI__Genius 12100 points

    Hi Damon,

    I suspect the added quiescent current in this setup may be due to the electronic load. Even if the load is disabled, an input resistance of 100kΩ would not be unexpected, which would add an additional 33µA of load in addition to the quiescent current. I would recommend re-testing with the load completely disconnected.

    Best Regards,

    Alex Davis

  • 0 in reply to Alex Davis
    TI__Prodigy 70 points

    Hi Alex,

    As you recommended, I disconnect the electronic load and the result is 130uA this time, which is also much higher than the typical value. Meanwhile, I also test the impedance of the electronic load, and its value is 280K.

    1: The quiescent current result does not make sense, please help me conduct an experiment on your EVM and send me the test result, thanks!

    Best Regards,

    Ying

  • 0 in reply to Damon(Shenzhen) Luo
    TI__Genius 12100 points

    Hi Ying,

    I'll double-check quiescent current on an EVM soon. I'll update within 2 business days.

    Best Regards,

    Alex Davis

  • 0 in reply to Alex Davis
    TI__Prodigy 70 points

    Hi Alex,

    I am looking forward to your reply, thanks.

  • 0 in reply to Damon(Shenzhen) Luo
    TI__Genius 12100 points

    Hi Damon,

    I assembled a TLV77333 onto an EVM with 1μF input and output capacitors. After assembly with no-clean flux, the PCB was cleaned thoroughly with isopropyl alcohol to remove all visible flux residue. Testing at the same conditions as in the datasheet (5.5V Vin with Enable tied to Vin) I measured an 87.6μA quiescent input current.

    I have a few suggestions to troubleshoot on your EVM: 

    1. Clean any flux residue remaining on the PCB. If no-clean flux was used, isopropyl alcohol, flux remover, or another chemical product may be necessary. If water-soluble flux was used, cleaning in an ultrasonic bath with distilled or deionized water is recommended. Flux contamination could be responsible for some additional leakage current, though I think it is unlikely to cause the ~50μA of additional current seen in your test.

    2. Swap the leads connected to the LO and I terminals of the DMM. This will help rule out the DMM as a source of error. If the measurement is identical in magnitude but with opposite sign (e.g. 130μA before, -130μA after swapping), that would suggest the source of the additional current is on the PCB itself. If the current measured is not identical, it may suggest an offset inside the DMM itself.

    3. Is there any possibility the TLV773 being tested could have been damaged, whether by thermal overstress, electrical overstress, or an ESD event? If so, as a last test, I'd recommend replacing the TLV773 and retesting

    Best Regards,

    Alex Davis

  • 0 in reply to Alex Davis
    TI__Prodigy 70 points

    Hi Alex,

    Thank you for your reply and I think the answers are very helpful to me. I will try the approaches list in the suggestions and reply to the customer. If they have further questions, I will contact to you.

    Best Regards,

    Damon Luo