Lpc2000

If you're struggling for space, why not use 0603 or smaller caps? 

---------------------------------------------------------------------------------

Owen,

if anything the LPC2000 devices do not have enough VDD/VSS pairs. If
you do not connect them all the chip MIGHT still run but usually the
pairs are responsible to provide power to logical blocks close to the
pins. Internally power is usually connected but you might loose some
voltage along the internal power traces.  If you do so, you reduce the
possible performance of the chip. 
As a result you could see random effects of some stuff not working or
temperature dependencies, almost impossible to find with debugging.
To avoid this trouble either for you and / or your customers, you
really want to connect all VDD/VSS pairs. For a clean power you should
also follow Leon's proposal to decouple each pair.

hth, Bob

--- In lpc2000@yahoogroups.com, "Leon Heller" <leon.heller@d...> wrote:
> ----- Original Message ----- 
> From: "Owen Mooney" <ojm@s...>
> To: <lpc2000@yahoogroups.com>
> Sent: Tuesday, February 08, 2005 8:59 PM
> Subject: [lpc2000] VSS and VDD lines
> 
> 
> >
> > I hope this question is not too ignorant!
> >
> > Is it necessary to link to all the VSS and VDD lines in the chip?
> >
> > I'm working on a tight 2 layer layout.
> >
> > Why are there so many?
> 
> I wouldn't just tie them together, I'd decouple each Vdd pin with
its own 
> capacitor. That's why they are brought out to separate pins.
> 
> Leon 
> 
> 
> 
> -- 
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