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TPS7H4001-SP: Output Changes when Input changes

Kang Quan
Prodigy 100 points
Part Number: TPS7H4001-SP

We are using TPS7H4001-SP to generate 0.95V output, input is 5V. we have two CCAs, one CCA : when input changes from 4.9V to 5.1V, Vout = 0.965V. another CCA: when input changes from 4.9V to 5.1V, Vout = 0.965V to 1.025V. it looks like it is not a design issue, maybe it is a manufactory issue, but we don't know how to debug it, could you guys provide any guidance?

  • 0
    TI__Genius 14540 points

    Hi, 

    I looked back on some of my characterization data and do not see this behavior even for a much greater PVIN variation. For instance,

    PVIN=3.0V, IOUT=12.0A, VOUT=0.9904453V

    PVIN=5.0V, IOUT=12.0A, VOUT=0.9905394V

    I do see that the VOUT does show more variation if the IOUT changes.  How are you setting the output current load?  I am using an electronic load.  Can you confirm that IOUT is remaining unchanged between measurements with PVIN=4.9V and PVIN=5.1V?  Also, at what load current are these measurements being taken?

    Thanks,

    Christian

  • 0 in reply to Christian Yots
    Prodigy 100 points

    Output 0.95V was designed to handle 9 to 10 A

    Yes, I can confirm Iout is remaining unchanged between measurements with Pvin = 4.9V and Pvin = 5.1V.

    it is a little hard to measure the load current at 0.95V rail, but I am pretty sure it should be about 3 to 5 A at 0.95V since we didn't load any image into FPGA yet.

    I can show you our LTspice simulation file, but I don't know how to attach the file in here.

  • 0 in reply to Kang Quan
    TI__Genius 14540 points

    Hi,

    Are you able to open circuit the rail so the converter is not loaded and then monitor output voltage versus input voltage.  I just want to understand if this is some interaction with the FPGA load.

    Thanks

    Christian

  • 0 in reply to Christian Yots
    TI__Genius 14540 points

    Hi Kang,

    Seems as if you might have resolved the issue since I haven't seen a response in a week.  I will close the thread but feel free to reply if you still have questions/issues and it should re-open.

    Thanks,

    Christian