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TPS65131 High Current Draw

Patrick Mcguirk
Prodigy 70 points
Other Parts Discussed in Thread: TPS65131

Hi,

   I utilized a TPS65131 on a board design to convert +5V input to +/-15V output.  The assembly appears good.  

   However, with the load disconnected, I can't bring up the converter. My +5V supply only makes it to ~1.3V before the +5V power supply current limits at 500 mA.

   Anyone have an idea of what this could indicate?  Attached is my schematic excerpt.

Thanks,
Pat 

  • 0
    TI__Guru 67355 points

    Hello Patrick,

    Please check if the IC can start with a power supply with higher input current limit or limit the inrush current by turning on one converter after the other. At the moment both converters are turning on at the same time.

    I would as well check if the startup is ok when removing the feedforward resistors and capacitors next to the 1Mohm resistors in the feedback nodes. For stability these parts are not necessary they just make the transient faster.

    Another possible issue could be the impedance between AGND and PGND. The part needs a low impedance connection between AGND and PGND. Please review the EVM layout for more details about this. An easy test to check this is taking an EVM putting all the components from your design on it and connect it to your power supply and load.

    Best regards,
    Brigitte