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LM5170: LM5170 IC FAILURE

Marco Bonfoco
Prodigy 20 points
Part Number: LM5170
Other Parts Discussed in Thread: LM51581

I have three electronic cards with the IC damaged at the first start, between VCC and GND i found about 1ohm.

The component is supplied by a voltage regulator with 11V output and the voltage (for the LM5170: the maximum supply voltage is 14V, raccomanded max 12V) is stable in all conditions.

During the power on the voltage rise to 11V in 47ms and there aren't overvoltages.

Do you have any suggestions?

  • 0
    TI__Genius 10385 points

    Hi Marco,

    Thank you for using E2E forums, regarding your query it seems the VCC of the IC is damaged, what is the 11V supply feeding into? VCC? 

    Is the waveform you attached for the Vin or Vout? Could you please share more information? it is impossible to suggest without any information.

    BR,

    Haroon

  • 0 in reply to Haroon Wardak
    Prodigy 20 points

    The LM5170 is supplied by a regulator with output voltage 11V directly connected on the pin N°19 (VCC) and the waveform attached in my precedent message  rappresent the startup of this voltage (11V). As you can see from the waveform there aren't overvoltages, the voltage rise up to the 11V and remain stable.

  • 0 in reply to Marco Bonfoco
    TI__Genius 10385 points

    Hi Marco,

    Was this waveform taken during the time it got damaged? our recommended voltage on this pin is maximum 12V, could you share the schematic and help fill out this excel sheet for your design https://www.ti.com/tool/download/SNVC205 ?

    BR,

    Haroon

  • 0 in reply to Haroon Wardak
    Prodigy 20 points

    No, the waveform sent cannot be the one at the time of the failure, I did not expect a breakdown of the IC. The fault occurred, without any reason, on electronic cards number 7,8,9 under test. I can not send you the diagram, but the voltage regulator is made by a SEPIC regulator made with the LM51581 that guarantees to me 11V (form the LM5170 datasheet: max RACCOMANDED voltage 12V and ABSOLUTE maximum 14V) to power the integrated LM5170. The voltage regulator is stable in any condition, even in case of overload.

  • 0 in reply to Marco Bonfoco
    TI__Genius 10385 points

    Hi Marco,

    Thank you for your reply, I am sorry to hear that. Could you tell me how many of the ICs you had this issue? is it possible that there was a spike on the external supply feeding the VCC and that might have caused this issue? normally 11V could be quite high as even a 10% spike would make it go beyond our recommended rating.

    BR,

    Haroon

  • 0 in reply to Haroon Wardak
    Prodigy 20 points

    Three IC, but i have tested only 12 electronic cards.

    About the spike, i have removed the damaged LM5170 from one electronic card and i have tested his voltage regulator (LM51581), you have see the waveform of the voltage regulator output. I have made many test on it, the voltage rise up no more of 11V. I have tested an overload too, when the load is removed the voltage goes to 11V without spikes. As soon as possible i change the LM5170 and i try to restart the card again.

  • 0 in reply to Marco Bonfoco
    TI__Genius 10385 points

    Hi Marco,

    So you were using LM51581 as a voltage regulator to feed the VCC of the LM5170's VCC pin?

    BR,

    Haroon

  • 0 in reply to Marco Bonfoco
    TI__Genius 10385 points

    Hi Marco,

    It is hard to say what is the cause of the issue as we do not have any waveforms from when this issue happened, would it be possible to recreate this and collect the waveforms this time and then we can deep dive into what is the cause and what is happening? just from what you have described I cannot say what is the reason for VCC pin being shorted or damaged.

    Thank you 

    BR,

    Haroon

  • 0 in reply to Haroon Wardak
    Prodigy 20 points

    Unfortunately I discovered that some wrong components were mounted on the electronic board by mistake, this is the cause of the failure of the integrated circuit. I'm sorry I didn't notice this earlier, thanks for the great support.