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TPS54334: breaks down on some pcb's

Grad Tacken
Prodigy 101 points
Part Number: TPS54334
Other Parts Discussed in Thread: TPS5430

Hi, I have a design with the TPS54334. And on some boards is breaks down. 

I made 4 boards and at 2 boards the TPS54334 is completely destroyed. I think it happens when switch on the board but I am not sure. I do not think it is not the 24V supply because I use two broads at the same supply and one is destroyed and the other not. The load is defined and shoot be within 2.3A.  

The two other boards run for two months and are switched off/on ones a day and newer break down. 

The layout is as specified in the datasheet.

Input 24V/8A

Output 5.3V, max load 2.2A (load is a MAX1978 Peltier cooler with current limit 2.2A and a DC Brushless Fan 100mA)

Input capacitors 10uF, output capacitor 40uF ceramic, inductor 10uH (5.5A)

Anyone an idea how this can happen or how to prevent this from happening?

  • 0
    TI__Mastermind 18510 points

    Hi,

    Please make sure it is not soldering issue.

    Have you tried to change new IC and duplicate the issue at the burnt board? If the issue follow the board, maybe there is bad component or bad soldering with the board.

    And please upload your schematic and layout, I will ask my teammate to reivew.

    Regards,

    Yuchang

  • 0 in reply to Yuchang Zhang
    Prodigy 101 points
    Hi, thanks for the quick response!

    I think the soldering was ok, made by a contract manufacturing services.The board was well operating for an hour and after a switch off/on it broke down. Just tested the electronics after the switcher and everything is ok. I used an external 5V supply instead of the switcher.
    On a previous board I replaced the switcher and after that the board is ok and is functioning for weeks already.

    Would be good to review the design, were can I upload the files? Gerber or Altium 17?

    Regards,
    Grad
  • 0 in reply to Grad Tacken
    TI__Mastermind 18510 points

    Hi Grad,
    You said after "switch off/on", then the chip got broken. what's the switch used for? and also what's the swicher you mentioned?
    Please help to upload schmeatic(PDF is ok) and layout(PDF and altium).
    I will forward to teammate, expert of this part, to help look into this.

    Regards,
    Yuchang

  • 0 in reply to Yuchang Zhang
    Prodigy 101 points

    Hi,

    With switched ON I meant switching on the 24V power supply.

    With switcher I meant the TPS54334.ee attached the schematic and layout (pdf). I can mail the Altium files but prefer not to post them in an public forum.Power5V3A.pdfSiPM_new_boardR2.pdf

  • 0 in reply to Grad Tacken
    TI__Expert 4035 points
    Hi Grad,

    I'm the application engineer who covers this part. There is no concern from your schematic related to TPS54334, but it's not easy or convenience to review your PCBLayout. If possible, you could send me the altium files to me or contact with me by mail (ryan-hu@ti.com).

    we attach importance to this issus, but it's very difficult to analysis this break down issue without any test waveforms, since you could repeat this issue, could you please capture some abnormal waveforms?

    BRs,
    Ryan
  • 0 in reply to Ryan Hu (BSR-MV)
    Prodigy 20 points
    Hi,
    I'm very intrested to this issue because I have exactly the same problem with TPS5430. Some pcbs work for months than it bursts. It does not happen often but one every 100 pcbs.
    Besides I confirm the problem alwais happens after "switch on/off" the power input.


    Best regards
    Giancarlo
  • 0 in reply to Giancarlo Dani
    TI__Expert 4035 points

    Hi Giancarlo,

    What's your Max input voltage? For TPS5430, the ABS MAX is 40V, usually even though the avg input voltage is only 32V, but when switch ON/OFF, the spike of the voltage would be very high if your power supply is ready and then you connect and disconnect the supply with a very high operating frequency.

    If your input voltage is in a high level, you could double check by decreasing the inputvoltage a little or parallelling a 36V or lower TVS with the input cap near to the device Vin pin. Rule out the factor of input voltage first.

    BRs,

    Ryan

  • 0 in reply to Ryan Hu (BSR-MV)
    Prodigy 20 points

    Thanks Ryan for your reply.

    The input voltage is alwais 24VDC, normally it comes from a commercial switching power (example MeanWell RS-50.-24). The output current (on 5V) is 0,5/1,5A.

    The ON/OFF cycle is very slow, our pcbs usually work in the automation and they are switched on/off no more two time a day.

    One TVS (SMA6J33A) is already present at input pin (about 10mm away).

    I tried to post schematics and layout but I didn't succeded, I try to send them by email.

    Best regards

    Giancarlo

  • 0 in reply to Giancarlo Dani
    TI__Expert 4035 points
    Hi Giancarlo & Grad,
    Since we have talked by mails and your problem has been solved, if no more feedback, I'd like to close this thread.
    Ryan