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  • TI Thinks Resolved

TPS65130: VPOS not correct

Part Number: TPS65130

I used below circuit to generate +/-12V from a +5V supply.  When VIN=5V/1A, VNEG=-11.7V, but VPOS=4.6V.  What could be wrong?

  • In reply to Cindy Wei:

    Hello Cindy,

    I did not see any problem in your schematic. It seems that the boost converter is enabled but is not switching (VPOS ≈ VIN-Voltage drop on D1_1 ). Have you checked the actual values of R3_1, R4_1 and R11_1 on the board. Also, please check the FBP, INP and CP pins at startup with an oscilloscope.

    Best regards,
    Diaara
  • In reply to Diaara:

    Hi, Diaara,

    Thanks for your reply.  I measured below components on board.

    * R3_1 = 264Kohm

    * R4_1 = 119Kohm

    * R11_1 = 0ohm

    I don't know whether the mismatch was caused by TPS65130.  Should they be close to the component values?

    When ENP=3V, FBP = 0.47V.  Below are the start up waveforms of INP and FBP.

    CP stays at 0V during the start up.

    Attached is BOM.

    BOM_TPS65130.xlsx

  • In reply to Diaara:

  • In reply to Cindy Wei:

  • In reply to Cindy Wei:

    Hello Cindy,

    Please replace R3_1 with a new resistor in the value that you have in your schematic and try the startup again. Normally such a mismatch cannot be caused by the IC.

    Best regards,
    Brigitte

    Best regards,
    Brigitte

  • In reply to Brigitte:

    Hello Cindy,

    Have you made any progress in the debugging or is it still not working?

    Thank you for your feedback.
    Best Regards.
    Ilona
  • In reply to Ilona:

    Hello Cindy,

    I haven’t heard back so I’m assuming you were able to resolve your issue. If not, just post a reply below (or create a new thread if the thread has locked due to time-out) – Thanks

    Best regards,
    Brigitte

  • In reply to Brigitte:

    Brigitte,

    I replaced R3_1 but didn't see anything different. The waveforms I observed at INP and VIN are different from what Diaara sent me. Mine didn't have the oscillating part. I tried two boards with the same result. I could not find anything wrong with schematic or layout. In the end, I gave up this design. Thanks for your help.

    Cindy
  • In reply to Cindy Wei:

    Hello Cindy,

    I am sorry to hear that you gave up the design. Is there anything that we can do to help you? e.g. would it help to send an EVM?

    Best regards,
    Brigitte

    Best regards,
    Brigitte

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