Re: Dual In-line Adaptor Board?
Posted: Mon Dec 21, 2009 5:37 am
That's very nice work Omer. :)
You seem to have nailed that "strip it down to the minimum" concept quite nicely.
The size looks good, but maybe it could be shrunk a bit more? Getting the size down will help in costs as it saves costs on the PCB and the SMD placement because you can get more PCB on each placement panel.
I'm won't pretend to know anything about XMOS JTAG but how many pins does the programming interface actually NEED? It would be great to get rid of that big ugly connector... Even if it must have 20 pins I think a vertical 2x10 plain pin header would save quite a bit of wasted PCB that the angled IDC connector takes up.
And what will the dissipation of U4 be like (1v regulator)? If you have 3.3v reg and 1v reg on board, there is a chance that the user will just connect 6v or 9v to it, and I think that is going to cause problems for a number of reasons.
What I originally imagined was putting the 1v reg on board and run from 3.3v. So the 1v reg has a fixed and predetermined dissipation. Then the 3.3v reg off board, so the module is powered from external 3.3v. This reduces size, cost etc and allows for a larger 3.3v reg. It is not unreasonable in terms of functionality in that the module is basically functioning as a 3.3v powered "chip". It is likely that other external devices will require the 3.3v too.
Moving the 3.3v reg off board and changing to vertical plain 2x10 header and some tweaking could get that PCB down to 70% of its present size.
You seem to have nailed that "strip it down to the minimum" concept quite nicely.
The size looks good, but maybe it could be shrunk a bit more? Getting the size down will help in costs as it saves costs on the PCB and the SMD placement because you can get more PCB on each placement panel.
I'm won't pretend to know anything about XMOS JTAG but how many pins does the programming interface actually NEED? It would be great to get rid of that big ugly connector... Even if it must have 20 pins I think a vertical 2x10 plain pin header would save quite a bit of wasted PCB that the angled IDC connector takes up.
And what will the dissipation of U4 be like (1v regulator)? If you have 3.3v reg and 1v reg on board, there is a chance that the user will just connect 6v or 9v to it, and I think that is going to cause problems for a number of reasons.
What I originally imagined was putting the 1v reg on board and run from 3.3v. So the 1v reg has a fixed and predetermined dissipation. Then the 3.3v reg off board, so the module is powered from external 3.3v. This reduces size, cost etc and allows for a larger 3.3v reg. It is not unreasonable in terms of functionality in that the module is basically functioning as a 3.3v powered "chip". It is likely that other external devices will require the 3.3v too.
Moving the 3.3v reg off board and changing to vertical plain 2x10 header and some tweaking could get that PCB down to 70% of its present size.