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Original question:

TPS61022: IC get damaged same times

TPS61022: TPS61022

Harit Shukla
Prodigy 70 points
Part Number: TPS61022

Hi,

e2e.ti.com/.../871303

I have same issue as explained in above link. Please check I have attached my layout is there any issue with my layout?

Regards,

Harit

  • 0
    TI__Mastermind 34201 points

    Hi Harit,

    The failure is related to the layout. 

    1. Two output ceramic capacitors should be placed close to IC. The below picture shows how C2 should be placed. C3 could be placed with 90 degrees rotated.

    2. Don't use thermal relief pattern because it will increase the PCB parasitic impedence.

    3. Don't connect FB trace with polygon as it will increase parasitic capacitance between FB to GND.

    4. Place vias close to IC GND pins and lower feedback resistor R4 GND pad to reduce return path.

    You can refer to the TPS61022 layout guideline.

  • 0 in reply to Zack Liu
    Prodigy 70 points

    Hi Zack Liu

    I have change my layout as you suggested please verify it tell me if any further changes required.

    Regards,
    Zack Liu

  • 0 in reply to Harit Shukla
    TI__Mastermind 34201 points

    Hi Harit,

    The new layout looks good.

  • 0 in reply to Zack Liu
    Prodigy 70 points

    hi Zack,
    we have changed layout of our PCB as per your guideline. the PCB Manufactured-Soldered-Tested successfully
    without any bug. We have tested for around 23 hours continuously. after some time when we were measuring temperature 
    of PCB (as one of the main application of this PCB is Lighting 2 Power LEDs of 1W each, so temperature of the board goes around 55-60 C) during measuring temperature, i have accidentally touched green marked area as per the attached image. the IC immediately failed. i have found that SW(PIN-2) and GND shows short.
    please share solution to this problem, (sounds like the main problem is not solved yet, as main issue from the beginning is IC fails whenever any person touches it knowingly/unknowingly).
    the Boost input in my case is battery (3.3V), so the input will be touched by user frequently. so will have to found exact and robust solution (also suggest me similar IC if avalible)
    please let me know if you need more details about the Circuit or PCB layout images etc.
    Regards,
    Harit shukla
  • 0 in reply to Harit Shukla
    TI__Mastermind 34201 points

    Hi Harit,

    Sorry to hear that. It seems to be a ESD(HBM) cause fail.

    I would to confirm with you:

    1. How many failed boards have you met and what's the failure rate now?

    2. Have you tried touching the board frequently? I mean you can touch it once the board is working.

  • 0 in reply to Zack Liu
    Prodigy 70 points

    Hello,

    The boards were actually working fine.
    up to 3 days in testing they were doing Okay.

    We don't know the exact failure cause.

    We were testing other things, And the IC just went off.
    IC is very sensitive to many things, So we want to figure out what precautions we will need to protect IC from being damaged for anything.

    The possible reasons defined by us which may cause the failure. We need other possible reason with the help of yours so we can actually identify the problem.

    1) IC is put up with PCB where there are LEDs. The PCB heats up, up to 80-100 degree.

    2) If IC is shouldered and found it working in PCB. Are there any chances of ESD failure afterwards it?

    3) What kind of other scenarios where IC can get failed.

    4) The failure ratio is now 30~40%.

  • 0 in reply to Harit Shukla
    TI__Mastermind 34201 points

    Hi Harit,

    The failure rate is quite high. Is the 30~40% failure rate for the updated pcb or for the original PCB?

    May I konw what's the downstream circuit of TPS61022? Would it possible that the downstream circuit would have a reverse energy back to TPS61022 output? We used to see some customer used TPS61022 to supply motor drivers. When motor driver is shutdown, the reverse current will charge the output capacitor to very high DC level, which cause TPS61022 EOS damage.

  • 0 in reply to Zack Liu
    Prodigy 70 points

    Hello,

    It's not possible for any back current due to motors,

    We don't have a motor in our circuit,

    The things we have,

    1) LEDs

    2) USB connectors.

    The live problem we faced was,

    While IC was giving 5V nicely,

    When someone touched the IC it failed.

    So if we can be sure the ESD is not an issue?

  • 0 in reply to Harit Shukla
    TI__Mastermind 34201 points

    Hi Harit,

    Understood. I just gave you an motor example that we met.

    TPS61022 can only survive with +- 2000V electrostatic discharge while the ESD voltage created by human may be higher than 10,000V. 

    I would suggest don't touch it when testing the circuit and adding a ESD protection circuit on your board to absorb the energy from USB connector.