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WEBENCH® Tools/LM5017: Problem to LM5017

Ravi Shidore
Prodigy 135 points
Part Number: LM5017

Tool/software: WEBENCH® Design Tools

When we give directly input voltage 72V DC to the LM5017 Pin no.2 , IC
will burst.
As per manufacturer datasheet it is operated on range 7.5-V to 100-V Input So,
why this happen?

I'm attaching my schematic block diagram for you to reference plz find and give me solution to this problem as early as possible,

Thank you.


problem to lm50170001.pdf

  • 0
    TI__Mastermind 30830 points
    Hello,

    Typically a failure at Vin suggests electrical over stress (EOD). This is because the Transient conditions cause the vin to over shoot at the device pin. Please ensure your layout is designed in such a way that the Cin Ceramic is very close to the IC . Also I note that the Cin Ceramic is only0.1uF? I am wondering if the 33uF is a ceramic and close to the pins of the IC? If not I would increase value of the Cin cap to 2.2uF and make sure its sitting next to Vin and Gnd of the device.
    Also that the cables to your board do not add inductance and as such the input can overshoot, to prevent this you can add a damping cap, which will be an electrolytic, say 150uF with an ESR of ~0.5ohm to 1ohm? This cap will dampen the input overshoot and minimize overshoot fo the input voltage upon a Vin transient.

    hope this helps?

    Kind regards,

    David.
  • 0 in reply to David Baba
    Prodigy 135 points

    I will work on it, Thank you.

  • 0 in reply to David Baba
    Prodigy 135 points

    1) Cin cap 0.1uf (smd 1206) is close to the IC and it is placed in between pin no 1 and 2.
    2)  33uf cap is electrolytic cap with value 33uf / 250V.

    3) Damping cap is not required as there is no inductance generated. 

    Plz reply

  • 0 in reply to Ravi Shidore
    TI__Mastermind 30830 points
    Hello Ravi,

    What is your output current requirement?

    I recomend the following modifications to your schmatic and retest.

    1. C26 - Make 1uF
    2. L2 - Choose 220uH with Isat >1.3A
    3. if using Type 3 Ripple injection
    (i) Change C23 to 3.3nF
    (ii) Change R62 to 0hom


    Kind regards,

    David.