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I'm planning on using the SN65MLVD080 differential line driver IC in a design. Its the first time however I've used an IC with many VCC pins (11 VCC pins and 12 GND pins). The data sheet doesn't mention anything about decoupling. I'll be working on a 4 layer board, so will have a ground and power plane to use. So I was imagining that I would decouple each VCC pin with a 0.1 µF cap pretty close to the pin following the usual rules of small trace paths etc.

So my main question is, do I have to decouple each of the 11 VCC pins independently? And if not, which pins would be required to have a decoupling cap?

SN65MLVD080 pin description

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Yes you should decouple each pair. Further, place decoupling capacitors on the top of the board, adjacent to the pads, and route the power/ground traces through them to the down-vias. This reduces the loop area of the decoupling so it will work better.

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Yes, you need to decouple them all if you want it to work properly anywhere near the speeds it can run at. A cap as close as possible for each pair of Vdd and GND pins closest to each other. Because a wire isn't just a wire. It's a piece of inductor.

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  • \$\begingroup\$ And the higher the frequency, the more a wire looks like an open and the more an open looks like a wire. At increasing frequency as the wire starts looking more open, the "open" capacitor starts looking more wirey. ;) \$\endgroup\$
    – jonk
    Commented Feb 28, 2022 at 2:31

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