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MiniDAC - AD1955 DAC with active I/V - Page 3

post #31 of 33
11/5/08 at 11:34pm
Yeah I'm not really looking to put 500 into that + PSU and what not. I'd love to build something I'd love to see a version that was a little more spaced out. Is it a single sided PCB? If it were I could probably just etch it my self since I have PCB material already. I'm not super worried about compactness. I just thought I'd look around and see what people have done and amazingly for how nice of a DAC it is there isn't a lot.
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post #32 of 33
11/6/08 at 6:34am
Thread Starter 
I think people are scared off by the fact that the DAC can only be configured by a microcontroller. Really though there is very little configuration and for standard CD source you don't even need a microcontroller connected, the default settings are fine. I still haven't got around to writing the code since I don't have a high sample rate or DSD source to use with it.

I think pretty much any board with this chip is going to be double sided, and you'd have a tough time home etching the 0.65mm pitch pads for the AD1955. A project for this is much better suited to a professional board house.

The DAC and I/V sections are pretty much a verbatim copy of the AD1955 evaluation board. I had a detailed PDF on it with full schematics but I've lost it - if anyone has a copy please let me know. They used AD797 for I/V and slightly different supply voltages, so the bias scheme is slightly different (formula in the datasheet). It wouldn't be too difficult to lay out a larger version of it with DIP-8 opamps and the like, but I'm not ready to take this on at the moment as a project. Maybe in the coming year.
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post #33 of 33
11/7/08 at 8:03pm
I agree about the double sided thing - I'm trying to keep the underside as a solid ground plane, and I've had to make some comprimises. I'm still not done with my full layout as I'm putting a PCM2707 on the same board as well and trying to head off any possible noise sources. Ideally I'd love to do it as a 4 layer board, but that would cost.

I've etched a 0.5 mm pitch before at home. It's doable using a sheet of glass to hold a printed transparancy over a photosensitized board. But in this case, considering the overall complexity of the board, cost of parts and the quality of the chip, a PCB is much preferred.
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