I bought a DAC AK4490EQ not knowing it has differential outputs. I was planning on creating a class A output stage using 2SA1313 to power some HIFIMAN HD5SE, but I don't know what actually comes out of a differential output? I am aware of the recommended circuits.
The bare chip. I'm building my own module for a Raspberry Pi 4 B 8GB sweet, this will simply be a DAC Amp module. I want to run pure class A on the output. This was the first time I'd looked at a DAC. I didn't expect a differential output, and I'm still not entirely sure which of several types of out is this differential output?
Is it a positive and a negative swing?
Is it they swing at the same time but in opposite directions?
I hear that there are design concerns because either the positive or negative are dominant over the other, is this an issue?
The recomended circuits requires an op-amp Low Pass Filter and a differential in single-ended pre-out. I considered alternatives and they weren't very good. I would've just used a coupling transformer but well I haven't given up on using a coupling transformer, but probably not.
Is it a positive and a negative swing?
Is it they swing at the same time but in opposite directions?
I hear that there are design concerns because either the positive or negative are dominant over the other, is this an issue?
The recomended circuits requires an op-amp Low Pass Filter and a differential in single-ended pre-out. I considered alternatives and they weren't very good. I would've just used a coupling transformer but well I haven't given up on using a coupling transformer, but probably not.
It is described completely on Page 61 of the datasheet and on Page 9. They are 2.8 Vpp centered on half of the reference voltage.
AOUT (typ.@0dB) = (AOUT+) - (AOUT-) = +/-2.8Vpp * (VREFHL/R - VREFLL/R) / 5
The outputs are 180 degrees out of phase with respect to each other.
The little formula wasn't obvious to me, and the literature I read, though mostly supported the idea of a 180degrees out of phase, still didn't leave me with a solid answer.
At any rate thanks for clearing that up.
At any rate thanks for clearing that up.
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You don't technically need to use both outputs, especially if you are not looking to preserve the best measured performance. It is highly recommended, though, since there is probably a lot of common-mode output that AKM intends for you to cancel.