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ADS131E08: AVDD bypass capacitor

user4365836
Prodigy 10 points

Part Number: ADS131E08

Good day.

 

Please tell us about bypass capacitor of ADS131E08.

It's described as to connect 0.1 uF and 1 uF to each of 19, 21, 22, 56, 59 pins. (datasheet page 62)

Does 21 and 22 pins require bypass capacitors each? (total 4 pcs)

Can we use a capacitor as common for two pins?

 

Best regards,

  • 0
    TI__Guru** 101005 points
    Hi,


    Normally, I'd look at the ADS131A08EVM and the board layout. The EVM can often be thought of as a reference design and I would copy the layout and decoupling capacitors from that. However, the EVM user guide photos aren't very revealing for the layout and the layer photos are too low in resolution to help.

    However, I do have a board here and I've taken a quick look. There are 5 pairs of capacitors from the schematic. Each are 1uF and 0.1uF pairs. Looking at the schematic C6/C16, C7/C19, C8/C15, C4/C14, C17/C18. However, on the board C7/C19, and C8/C15 are not populated, meaning that the decoupling capacitors are common for multiple pins.

    For the EVM, I can't see all of the layout, but based on the EVM user's guide pictures pins 19, 21, and 22 share a common connection and decoupling capacitors. It also looks like 56 and 59 also share a common connection with 54. For these connections, both tie back the C6/C16 and C17/C18.


    Joseph Wu