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Question on a TVP5150 capacitor

Anonymous
Anonymous
Other Parts Discussed in Thread: TVP5146, TVP5146M2

Hi All,

 

I would like to ask a question on capacitor connection for TVP5146.

 

 

 

 

In the page for TVP5146M2 connection, found in EVM6437 schematics, capacitor C294 is with a plus symbol.

 

What does the plus symbol mean?

 

I also noticed that its footprint in PCB is quite different from other types of capacitors. So what type of capacitor it is, and why is it used here along with TVP5146?

 

 

 

 

Thanks,

Zheng

  • 0
    TI__Genius 16810 points

    Zheng,

    The schematic symbol was for a polarized cap ( tantalum, electrolytic type), whereas the board may have actually used a ceramic non-polarized type.  The "+" and cap orientation is only important if polarized caps are used.  The 10uF cap is larger, so a larger footprint is used.  It is used to help filter the power supply.

  • Anonymous
    0 Anonymous in reply to Larry Taylor

    Dear Larry,

     

    Briefly and the most importantly, what is the difference between polarized and non-polarized type?

     

    There must be a reason for using polarized capacitor, so doesn’t it matter(any adverse effect: noise, etc.) if the board replaces it with a non-polarized type?

     

     

    Zheng

  • 0 in reply to Anonymous
    TI__Genius 16810 points

    Unpolarized, like ceramic, is typcially limited to smaller capacitance values.  Larger capacitance values are typically polarized, like tantalum and electrolytic.  10uF is near maximum for ceramic type caps.  A 10uF ceramic cap may be physically smaller than a polarized cap but may be more expensive.  In this case, either type can be used for the 10uF supply decoupling/filtering, but if polarized caps are used, the cap must be oriented correctly on the PCB.  The 0.1uF caps at the TVP power pins will be the most important for high frequency supply decoupling.

  • Anonymous
    0 Anonymous in reply to Larry Taylor

    Dear Larry,

     

    I got it, thanks very much for your detailed and clear answer.

     

     

    Zheng

  • Anonymous
    0 Anonymous in reply to Larry Taylor

    Dear Larry,

    Do you mean these capacitors?

     

    May I also ask about the concept of "decoupling"? I only know that there are two types of coupling: DC and AC. So regarding these power pins, is this DC or AC coupling?

    I lack fundamental knowledge on alternating currents (though I know Maxwell equations), and I have found it is not that easy to understand the charging/release process when AC, capacitor, inductor and frequency are involved. Is there a quick and intuitive way to understand what "decoupling" is?

     

     

    Zheng