At 15:22 06/02/17, sbdwag wrote:
>f anyone has time please critique my first attempt<snip>
>Does anything stand out? All comments are appreciated.
>
>http://www.wagsterstuff.com/photos/psbd.jpg
>http://www.wagsterstuff.com/photos/psobj.jpg
I don't mind the layout not being perfectly symmetrical.
What I don't understand is why the negative output is
a model of good decoupling and the positive output
is quite the contrary.
On the negative side, capacitors C6, C8 are directly on the
output track and on a large common ground island.
On the positive side, capacitors C5, C7 are each on a stub
track off the output track and they are on separate ground areas.
These are split by the hooked track which runs between the
pads of both capacitors though there seems no reason why
it should since there is a direct path available.
Also close to having isolated copper fill islands there too.
As part of this layout style, three tracks seem to run to
a star point at the diode when what should happen is
that the output current track visit each decoupling
capacitor, thus eliminating the stub tracks.
Caps C10, C9 could be closer to their Adjust pins, too.
On the input side reservior caps C1, C2 are on stubs:
the rectifier output should be taken to the reservior
then the reservoir to the regulator Input.
Wouldn't hurt to have C3, C4 on the current path too
but priority is to get them as close as possible to their
Input pins because they help guarantee regulator stability.
Eliminate stubs, shorten current paths, minimize current loop areas.
Regards. Len Warner
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