On 29 Oct 2010 at 0:04, David wrote:

> (Reposting with tag)
>=20
> Thanks to all for the comments in the "routing SMD boards" thread, which=
=20
> were really helpful in finishing this off.  Opening this to critique on=20
> here will be fun I'm sure :)
>=20
> The circuit is a FT232R breakout, for use with breadboards.  It exposes=20
> all of the serial pins and includes the LEDs, selectable VCCIO and=20
> switched USB power with soft-start.
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> Never having used this chip (and being a complete electronics amateur) I=
=20
> am unsure how well these different features will interact.
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> The board is designed to meet BatchPCB 2-layer rules.  That does mean=20
> fairly large vias.
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> Schematic: http://tinyurl.com/2uhbr68
>       Route: http://tinyurl.com/33kxen6
>        Silk: http://tinyurl.com/3575prt
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> Constructive feedback welcome.

In the schematic T1 is a P channel MOSFET and it appears Drain/Source may b=
e=20
the wrong way around from what is intended. The symbol for the body diode g=
ives it=20
away... with the orientation shown the diode will conduct and USB5V_SWITCHE=
D=20
will be on all the time regardless of the state of the Gate.

I'm not sure what C1 is there for. At power on, assuming C1 is discharged, =
it will try=20
to turn the MOSFET on - probably creating a a power on glitch in=20
USB5V_SWITCHED which may not be desireable.

Otherwise it looks good~!

--=20
Brent Brown, Electronic Design Solutions
16 English Street, St Andrews,
Hamilton 3200, New Zealand
Ph: +64 7 849 0069
Fax: +64 7 849 0071
Cell: +64 27 433 4069
eMail:  brent.brown@clear.net.nz


--=20
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