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TPL7407L - Ccom

Hirotaka Matsumoto
Guru 27525 points
Other Parts Discussed in Thread: TPL7407L

Hi all

Would you mind if we ask TPL7407L?

On the datasheet P9 shows that Ccom is 0.1uF.
We guess that this is to reduce noize, why is 0.1uF used for?
And if  it has some formula to caluculate, could you let us know?

Kind regards,

Hirotaka Matsumoto

  • 0
    TI__Mastermind 26065 points
    Hi Hirotaka,

    This 0.1uF should be the power decoupling cap which stable the Vcom voltage when loads change.
    For motor driver device we normally recommend 0.1uF plus with a bigger bulk cap. That is for inductance load or high peak current. Should be the same senario for TPL7407L. If only a level shifter use, with small current, one 0.1uF will be enough.

    Best regards,
  • 0 in reply to Wilson Zuo
    Guru 27525 points

    Wilson san,

    Thank you for your reply always!

    How much of a bigger bulk cap is fitable in case of unipolar stepping with 150mA(RMS)?(22uF upto 47uF?)
    Does it depend on situation?

    Kind regards,

    Hirotaka Matsumoto

  • 0 in reply to Hirotaka Matsumoto
    TI__Mastermind 24485 points
    Hello Matsumoto-san,

    Wilson is correct. This is simply a power decoupling capacitor to help keep the voltage to the device stable in cases where the device may get loaded quickly.

    There is not necessarily a cut and dry method of determining cap size. It really depends on what the loading conditions are and what kind of ripple you are willing to accept on the device. Bigger will help to reduce ripple due to transients, but 0.1 to 1uF should be plenty. You shouldn't need something like a 22uF capacitor.

    Best,
    Michael
  • 0 in reply to Michael J Schultis
    Guru 27525 points

    Michael san

    Thank you very much for your reply!
    OK, we got it!

    Kind regards,

    Hirotaka Matsumoto