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ADS8556: About decoupling capacitors

Ryu Yamashita
Genius 3685 points
Part Number: ADS8556

Hi team,

The decoupling capacitors connected to AVDD are written in the pin description column as 0.1μF and one 10μF for each pin.
However, Figure 43 on p36 shows a 40μF capacitor connected.
Also, the EVM has six 1μF and one 10μF connected.
What values should I connect as decoupling capacitors?
Please let me know the minimum value and how to connect it.
Also, up to what tolerance should I connect the capacitors?

Sincerely.
Ryu.

  • +1
    TI__Guru 63915 points

    Hello Ryu,

    Please follow the datasheet recommendations of at least one 10uF bulk capacitor for the full IC, plus one 0.1uF capacitor for each of the main AVDD inputs.  Increasing these capacitors to 1uF as the EVM has done will further help with power-supply noise rejection and decoupling.  Place one capacitor at each of these locations: Pin 26, Pins 34/35, Pins 40/41, Pins 46/47, Pin 50, Pin 60.   

    The tolerance doesn't really matter that much, but be sure to put the correct voltage ratings of the capacitors and use at least 2x larger voltage ratings than the application (e.g. for a +5V rail, use at least 10V capacitors).  X5R/X7R dielectrics are better than Y5V. 

  • 0 in reply to Collin Wells
    Genius 3685 points

    Hello Collin,

    Thank you for reply.
    I understand very well.

    Sincerely.
    Ryu