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REF5030A-Q1: The output voltage of chip REF5030AQDRQ1 is abnormal

Chong Yu
Intellectual 1435 points
Part Number: REF5030A-Q1

Hi,

My customer need assistance.

The output voltage of the chip REF5030AQDRQ1 is only about 2.8V, instead of the nominal 3.0V of the chip.Input voltage 3.3V, working environment temperature 20°C.The schematic diagram is shown in the attachment.Among the 30 chips we purchased, there was a faulty chip.

Please help. Thanks.

  • 0
    TI__Intellectual 1210 points

    Hi Chong Yu,

    Can you share a oscilloscope photo of the output signal? There is a ESR requirement for output capacitance and if this is not met, instability may occur.Do you know what is the ESR of the output cap being used in this circuit?

    FYI

    Jake

  • 0 in reply to Jake F
    TI__Intellectual 1435 points

    Hi Jake,

    There is the photo attached by customer:

    I am asking customer for ESR value.

    Regards.

  • 0 in reply to Jake F
    TI__Intellectual 1435 points

    Hi Jake,

    Customer told me ESR is 6.8uF,X7R. I thought it should be with an ohm unit. But cusomter insisted that this is the ESR.

    Regards.

  • 0 in reply to Chong Yu
    TI__Intellectual 1735 points

    Hi Chong,

    You are correct that ESR is equivalent series RESISTANCE, which is ohms. They are likely using an MLCC which has low ESR. Can they get a cleaner scope shot? The noise on that signal makes it hard to tell if those are small oscillations or if it is just a low bit depth. Also try replicating this on another part to confirm it is the setup and not that single IC.

    -Tony

  • 0 in reply to Tony!
    TI__Intellectual 1435 points

    Hi Tony,

    Customer attached a figure of ESR.

    And this is the output voltage waveform of REF5030AQDRQ1 when the timeline is 1us. It can be seen that there is no oscillation in the waveform.

    Customer mentioned that among the 30 chips they purchased, there was one faulty chip.

    Regards.

  • 0 in reply to Chong Yu
    TI__Intellectual 1735 points

    Hi Chong,

    It looks like the MLCC has essentially no ESR, but I doubt that is a factor in this given the rest of the info shared here.

    If it is 1 in 30 parts is a failure, then there is clearly something wrong with the part. These parts are voltage trimmed in the factory, so something would have had to happen afterwards to cause an error like this.

    With the info in front of me, there are three things to consider: design, handling and use. If we have full details of the design, assembly process and application usage we may be able to make some headway here.

    Were all these tested beforehand and the customer found a single faulty chip, or was this an RMA that was tested and found to be faulty?

    -Tony

  • 0
    Prodigy 50 points

    Yes,we  tested beforehand and  found the faulty chip.

  • 0 in reply to Tony!
    TI__Intellectual 1435 points

    Hi Tony,

    user1745073 is customer who is facing this issue. Please keep discussing.

    Regards.