what's the best ground pin on the Teensy to return the DAC signals to?

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jwatte

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Title says it all :) This question was hidden in my massive wall of text previous question, so let's break it out simply:

What's the best ground pin on the Teensy to return the DAC signals to?

I'm assuming AGND for now. I route AGND to a central point, where a "cuttable board jumper" connects it to the GND plane.
 
I have a 1oz ground plane, only pierced by some vias and through hole pads (such as for mounting the teensy.)
Are you saying that making a small zone for AGND that connects to GND only in one spot, isn't going to bring noticeable improvement? I'd happily just fill and connect it all to the unbroken plane.
 
If you have a look at the Teensy schematics you'll see that Agnd has filtering separating it from the digital gnd, so if you were using it idea would be to keep it isolated from normal gnd and arranged to minimise EMI from other sources. Unless your application is chasing the last couple of significant digits in ADC reads probably not going to justify the design effort.
 
My connector is right next to the AGND pin (which is annoyingly far from the DAC pins, btw,) so hooking the return to that rather than the GND plane is not a bother for me.
I'll just totally separate the AGND from GND on the board, and rely on the Teensy ferrite to de-couple transients.
 
If using agnd, make sure whatever you are doing with the signal is noise free and running through it as well. If your sensor is grounded through digital ground then you may be better of using that gnd so any transients effect both.

Not actually sure if the DAC signal is gnd reference or agnd referenced. It's main purpose is for ADC where you are using seperate Vref and Agnd levels into the ADC, with the sensor being ADC'd powered from a stand alone high stability supply.
 
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