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TPS65130: TPS65130 voltage output issue from calculated values

Joao Campos
Prodigy 10 points

Part Number: TPS65130

Tool/software:

Hi Team,

I'm designing a DC/DC converter that uses 5V DC directly from the USB VBUS and is meant to output +/-15V.

The problem I'm having is that I have 0V at the output capactiors of the V_POS (+15V) and -5V at the V_NEG (-15V). Load-wise, I just have 350kohm load for the time being on each, which is nothing current-wise.

My schematic is as below:

My layout is as below:

I've also looked into other posts on this part number and I've also tried adding the 51kOhm resistor as suggested on TPS65130: Inverting converter is not regulating under load - Power management forum - Power management - TI E2E support forums and TPS65130: TPS65130 negative output issue - Power management forum - Power management - TI E2E support forums, however the result is still the same.

Some information on the components being used:

  • Schottky diode: MBRM120LT1G
  • PMOS: SI2323DS-T1-GE3
  • L2/L3: NRS6028T4R7MMGK

Would it be possible to provide some guidance? Please let me know if any further information is required.

Thank you very much!

  • 0
    Prodigy 10 points

    A few more bits of information from the voltages measured:

    • Vin: 3.83V
    • INP: 0V
    • INN: 4.5V
    • FBN: 1.36V
    • Vref: 1.21V
    • CP: 1.23V
    • CN: 0.88V
    • FBP: 0V
    • INP: 0V
    • INN: 4.5V
    • OUTN: 11.2V

    The source voltage on the USB is 5V (measured 5.02V) but once the DC/DC circuitry is connected, it drops to ~4.5V (which makes sense with the INN measured voltage).

    One other aspect is that the DC/DC converter starts to heat up as soon as it's powered on. I'm not leaving it powered for too long to prevent any permanent damage.

    Also, to note that this is reproducible on more than one of our assembled boards.

  • 0 in reply to Joao Campos
    TI__Expert 5771 points

    Hi Joao,

    Our expert will reply to you later. Thanks for you patience.