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TPS62150: Device damaged during start-up

Joe Miller
Prodigy 160 points
Part Number: TPS62150
Other Parts Discussed in Thread: TPS63710

Dear Sir/Madam,

I have a board that is fully TI and the +4V5 DC/DC (TPS62150) keeps getting damaged during power-on.

Three out of three boards have failed. Some powered a few times before failing.

The devices are:

(1) TPS25940AQRVCRQ1 for input protection. +12V input.


(2) TPS62150 for +12V to +5V5
(2.1) TPS7A4701 for +4V5. Load current = 0.5A


(3) TPS63710 for +12V to -5V5

(3.1) TPS7A3301 for -4V5. Load current = 0.5A

I have pulled of the TPS62150 and connected a bench supply to input of TPS7A4701 and the board power and functions fine.

I have looked at the TPS63710 to TPS7A3301 power-on and it looks fine. The start-up time is about 50ms.

I cannot check the TPS62150 power-on however the  SS/TR capacitor is 3n3F approx. 1.65ms.

Only the TPS62150 gets damaged. What could possibly cause the TPS62150 to get damaged?

Regards Joe

  • 0
    TI__Mastermind 26740 points

    Joe,

    Few questions:

    1. Can you please check the TPS62150 startup independently?

    2. Is the device failing during startup?  You may need to replace TPS62150 IC and try this out again while watching startup waveforms on VIN, SW, SS/TR.

    3. Does the device work properly for some time before powering down?

    4. What is output current requirement on the TPS62150 load?

    5. Do all boards exhibit same behavior?

    Please check if section 11 layout guidelines on datasheet pg 29 and 30 are being followed and ensure the thermal pad is soldered correctly -.it must be connected to AGND (pin 6), PGND (pin 15,16) and common ground plane. Check layout example figure on page 29 section 11.2. If you can share schematic, BOM and layout, we might be able to review it.

    Regards,

    Amod

  • 0 in reply to Amod Vaze
    Prodigy 160 points

    Hi,

    Thank you for the response.

    When the TPS62150 fails there is jump in supply current on the +12V input. 

    This is how I know something has gone wrong with the TPS62150.
    When this happened I removed the TPS62150 and tried powering just the negative rail and the current draw is much higher on the TPS63710.
    To get start-up captures for the negative rail I had to inject a voltage into the output of the TPS62150. When this was done both supply current draw was as expected.  

    If a split supply powers up at different times can current be forced through the load device into the other rail?

    ie. can the output of the TPS62150 sink current. I do not know why the TPS7A4701 is never affected just the TPS62150.

    >> 1. Can you please check the TPS62150 startup independently?

    I will need to wait for parts to re-test.

    >> 3. Does the device work properly for some time before powering down?

    Failure only happens if the boards have been sitting over night then turned on.

    >> 4. What is output current requirement on the TPS62150 load?

    440mA on the TPS62150. 

    >> 5. Do all boards exhibit same behaviour?

    Yes.

    The layout follows the EVM.

    I can supply whatever files if you can contact me off line.

    Regards Joe

  • 0 in reply to Joe Miller
    TI__Mastermind 26740 points

    Hi Joe,

    I sent you an email to get more details on the design. We can circle back here once done or can continue communication via email.

    Regards,

    Amod