Aroio HAT masse

[audiogio]

Hi,
sorry for the language but I cannot speak German.

A question about Aroio Hat. On the back side of the card there is a jumper connecting DGND (DAC digital section ground) and AGND (DAC analog section ground) and other two jumpers connecting RPI +5V to AVDD (DAC analog section) and DVDD (DAC digital section).

Aroio DAC HAT jumpers.jpg (254.05 KiB) 19160 mal betrachtet

As expected, from my tests, without the jumpers AVDD and DVDD are not connected togather or to RPI +5V, while AGND and DGND seem to be connected togather and to RPI ground inside the Aroio DAC HAT card.

So if you have three different PSU for RPI, digital DAC part and analog DAC part you can just
- take all jumpers away
- power up RPI via the normal USB connector (or through +5V and ground GPIO pins)
- power up the digital DAC section connecting digital PSU +5V to DVDD and digital PSU ground to DGND
- power up the analog DAC section connecting analog PSU +5V to AVDD and analog PSU ground to AGND

Is all this correct?

If this is correct, I cannot understand the reason for the jumper between AGND and DGND: if the two lines are already connected elsewhere, the jumper should not be necessary at all, and possibly build up a ground loop.
Could you please clarify this point?

Thank you in advance
Giorgio

[audiogio]

No one can explain me the situation? I did not mean to be argumentative, I am just really worried I might have missed or overlooked anything important...
Thank you

[Hanno Sonder]

Dear Gorgio,

in the datasheet of the DAC-Chip PCB5122 you find in chapter 11.1 Layout Guidelines. It sais

The PCM512x family of devices are simple to layout. Most engineers use a shared common ground for an
entire device. GND can consider AGND and DGND connected

.
So actually there is no need to seperate those, but we added the jumper so we can optimize GND-routing in our Aroio-products.

Best regards
Hanno Sonder

[audiogio]

Thank you Hanno,
in the meanwhile I tested the Aroio with a separate linear power supply on AVDD only, and it seeems to sound a tad smoother and polite than with a single supply for both DAC and RPI. Not bad at all, indeed.

regards
Giorgio