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TPS5430: VERY STRANGE BURST NEAR PIN 7 OF TPS5430

Mirkuzz
Prodigy 30 points
Part Number: TPS5430

Hi all,

In the last production cycle we are the TPS5430 bulk regulator burst up the pin 7 !!!. I think is the internal mosfet.

You can see in the photo attached here. The TPS5430 are powered with 24Vdc. 

Do you have any idea why it happens? Can you help me to resolve this problem?

  • 0
    TI__Mastermind 22301 points

    Hi Mirkuzz,

    It looks like your diode is damaged? Is that diode rated for the voltage / peak currents? The maximum current limit of the part is up to 6A so your diode needs to be rated for that.

    If your diode shorts then the internal MOSFET can be damaged as well.

    Hope this helps,

    Orlando

  • 0 in reply to Orlando Murray
    Prodigy 30 points

    Hi,

    In the last production cycles we don't have problems with the step-down circuit.

    All the problem come up with the TPS5430 with marking code TI 944 ZE8YG4

    I make some test with this production batch (TI 944 ZE8YG4) and I see is much more

    sensitive to disturbances on the power line that cause it to break and burns.

    TPS5430 of different series purchased in the past never break compared to this series with the same stress test.

    As a stress test I intend to supply the board with 30Vdc with a two-meter cable, thus creating spikes at the input of the integrated circuit due to the inductance of the cable itself.

    However, the problem arose by feeding them at 24Vdc always with a two-meter cable during assembly.

    Do you have any information about it ?

    Mirko

  • 0 in reply to Mirkuzz
    TI__Mastermind 22301 points

    Mirko,

    Are the problems only with (TI 944 ZE8YG4) TPS5430 IC's and not the other TPS5430 IC?

    Can you share scope plots of the failure?

    Yes if the wire inductance cause a spike that would be bad, also the ceramic capacitance should cause ringing on the VIN node which is also bad.

    Can you place a cap with ESR (like electrolytic) on the VIN node to dampen the ringing from wire inductance?

    -Orlando

  • 0 in reply to Orlando Murray
    Prodigy 30 points

    Orlando,

    Yes, is the problem is present only in the serie TI 944 ZE8YG4 of TPS5430 IC and not other TPS5430.

    Days ago I did the same tests on a new reel marked 5430 | TI 044 | ZHT3G4  and they didn't have any problems.

    In the attached image you can see the spike induced in the input pin of the TPS5430.

    The series with problems burns after a couple of this spike with 24Vdc of power supply

    (voltage used during the production test of the usb charger) while the other series never burns even after 200 spike with 30V of power supply

    (voltege that I use in laboratory to stress the IC once I understand the problem).

    In the picture below you can see the spike induced with 24Vdc power supply

    For the next production batches, we have inserted a NTC on the regulator input to dampen the spikes with excellent results. No more spike in the input of the TPS5430.

    How can we explain the fragility of the series 944 ZE8YG4 ?

    Thanks so much,

    Mirko

  • 0 in reply to Mirkuzz
    TI__Mastermind 22301 points

    Mirko,

    There will be some part to part variation as well as variation between lots as you see.

    We test to make sure the part is within the specifications listed on the electrical characteristics table, but anything outside of that cannot be guaranteed.

    I actually expect ~45V spike to damage the device as the VIN is exceeded, I'm not sure why the other device was not damaged by the spike.

    Hope this helps

    -Orlando