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LM5180EVM-S05: About Input EMI filter.

teritama
Expert 1640 points
Part Number: LM5180EVM-S05

Hi team,

We want to use this device for size limited application. In hits EVM, C2 is equipped as input filter.

If we could change this electric capacitor to  more small one, the size requirement may be achieved.

Could you please advise on the tolerance for smaller capacitors or other parts?

※As for the transformer, we are already considering it.

best regards,

teritama

  • 0
    TI__Mastermind 27030 points

    HI

    pls refer to datasheet 8.2.1.2.7, normally , you need to know the input ripple requirement. and for avoid input choke resonant with input cap when there is no room for electrical cap, it is better to have ceramic cap series with 1ohm for damping 

  • 0 in reply to Daniel Li14
    Expert 1640 points

    Hi

    Thank you for reply.

    >pls refer to datasheet 8.2.1.2.7, normally , you need to know the input ripple requirement.

    ⇒In Equation20, Cin means sum of C2, C4 and C5, right?

    And I think that if LC filter(L2 and C4) was removed, the input noise through to trance and affect to output voltage almost directly. So this condition cause critical bad EMI characteristic. Is this understanding correct?

    best regards,

    teritama

  • 0 in reply to teritama
    TI__Mastermind 27030 points

    if you remove L2, then Cin means C2, C4 and C5, if you not remove L2, it means C5 and C2, C4 with L2 is filtering the noise from flyback.

    Removing L2 will cause bad EMI especially at your working frequency .