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TPS65150-Q1: The output is abnormal

Cera Wei
Intellectual 2010 points
Part Number: TPS65150-Q1
Other Parts Discussed in Thread: TPS65150

Hi team,

My customer are using TPS65150, but the output is abnormal, and the boost output is the same as Vin. VGH and VGL are 0V. The schematic is as follows:

Do you have any comments?

Thanks,

Cera

  • 0
    TI__Intellectual 2010 points

    Hi team,

    We tried to disconnect the SUP pin with the boost output, the boost output turns right. It's so weird. 

    We also checked the all the capacitors and resistors, they are all correct. 

    Thanks,

    Cera

  • 0
    TI__Intellectual 2010 points

    Hi,

    We found that if we set the boost output to 13.5V, it works. But when we set it to less than 11V, the output is wrong, and the chip seems not working.

    The VGH is 18V and VGL is -12V.

    Could you help me answer the following questions:

    1. Is there any threshold for the boost output voltage? Or is there any limitation for the VGL and boost output?

    2. As you can see in my schematic, the VGH is set to 18V. But the output is 23V.  Do you know why?

    3. What's the meaning of VGL output voltage? Any VGL smaller than -2V is ok? 

    Thanks,

    Cera

  • 0 in reply to Cera Wei
    TI__Guru 65200 points
    Hello Cera,

    FDLY makes sure that the whole IC shuts down if one of the outputs falls out of regulation for too long. Please check the datasheet for the timing. You can disable FDLY by connecting the pin directly to VIN.

    With the voltages you mention above, I am sure that the problem is caused by the VGL charge pump. The negative charge pump is configured as a inverter and therefore cannot deliver more than -Vs+2*(diode drop). Therefore it is not possible in this configuration to create -12V from -11V. See more details on the function of the charge pumps in this application note: www.ti.com/.../slva794

    If you are adding a second stage to the negative charge pump, the circuit will function properly.

    Best regards,
    Brigitte
  • 0 in reply to Brigitte
    TI__Intellectual 2010 points
    Hi Brigitte,

    Thanks for your help. I changed the VGL to -4V, it finally works.

    Regards,
    Cera