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LM3151 issues

Kai Kloepfer
Prodigy 60 points

2313.Vreg WebenchReportsServlet.pdf

Hi all,

I built a board directly based on a webench design that is attached. When I plug in my power source (LiPo battery pack) I get nothing on the output. The IC is seated correctly on the PCB and I measure ~5.9V on the VCC pin. There is 7.9v(source voltage) going into M1 but nothing coming out. I'm completely stuck, any ideas?

Thanks,

Kai Kloepfer

  • 0
    TI__Mastermind 45250 points

    Kai,

    Everything looks OK in the design.

    What is the voltage on the EN pin?

    Do you see any activity on the HG or LG pins?

    What is the voltage at the BST pin?

    Are you seeing this on a single chip or on multiple boards?

    If this is a single board please try another IC as the converter should start with the conditions that you stated.

    Please let me know the results of your tests.

    Richard Elmquist

     

  • 0 in reply to Richard Elmquist
    Prodigy 60 points

    Thanks for the quick response,

    The EN pin was left floating, measuring against ground, the voltage varies from ~ 1v to 500mv.

    300mv on HG and LG, both fairly steady 

    BST pin: 5.23v

    I will go replace the chip and see if I get anything different. Unfortunately I don't have access to a scope right now, so the above readings are made with a good quality multimeter.

    Thanks,

    Kai Kloepfer

  • 0 in reply to Kai Kloepfer
    TI__Mastermind 45250 points

    Kai,

    The EN voltage should be higher than this.

    Can you put a 5V or 3.3V signal into the EN and see if it starts?

    Let me know if it operates.

    Please let me know if you have further questions.

    Richard Elmquist