- regarding the edge_cuts; I realized I don't actually have board outline. I just have the measurements for the chip itself from the Analog Devices library.
Howdy! The measures aren't going to help—the manufacturer needs an outline in the edge.cuts layer that they can use to size, position, and route your board. This is as simple as adding a rectangle that encloses all your traces, parts, and mechanical elements to that layer; if you want to post your KiCAD project, I'm sure one of us can help you add it.
- This is the hard part for me; I'm not sure where in datasheet I should look for regarding the decoupling caps and what values I would need. My main idea is that once I have this board with the chip I can connect it directly to arduino nano ? Does that make sense ?
I understand what you want to do, but it's not
quite right. Bypass caps should be as close to the chip as possible in order to be effective, so mounting them outside the board may not achieve the results you want. (In all fairness, the chip may work perfectly fine regardless, but then again it might not, at which point you won't know why.)
There is no shortcut to reading through the datasheet to figure out what support circuitry you may need; I know it can be a slog, but, without it, the risk of malfunction and/or failure are pretty high
A cursory look at pages 20 and 21, which show the pin assignments, tells me that you need capacitors between these pins and ground:
- A 4.7µF cap on VREF_1V82
- A 470nF cap each on VBIAS_CAP, VREF_2V5, and DVDD_REG_1V8
- There is an additional AVDD_REG pin that could use a cap for the internal LDO regulator; it doesn't specify a value, so maybe I would throw anything between, oh, say 1µF and 10µF (but I'm just guessing, someone with more experience might be able to give you a better idea).
Note also that the chip operates between 2.8 and 3.6V, whereas most Arduinos operate at 5V; if that's the case for you and your Arduino doesn't provide 3.3V outputs, you will need to add some preregulation from 5V to 3.3V so that you can power the device from the Arduino's VCC pin, and then level shifting at least in the direction from Arduino to the AD5941 so that you can safely interface the Arduino's output pins to the '5941's input pins (this won't be necessary in the other direction). Again, you may get away without the level shifting (but not the 5V->3V3 regulation!), but you'd be taking the chip's life in your hands every time you put power to it
Note that this last bit of support circuitry doesn't
have to be on your board—you could just power the chip from an external 3.3V supply and use a commercially available level shifting breakout (like
these ones, which are very cheap and readily available), for example, just as long as you don't forget.