At 05:18 AM 2/13/2010, you wrote:
>ivp ha scritto:
> > Dario, can you guarantee the voltage drop across the diodes as the
> > load varies won't affect the circuit ? For example,
> >
> > 1N4001 0.7V @ 10mA, 0.75 @ 100mA, 0.9V @ 1A
> > BAT46 0.25V @ 1mA, 0.4V @ 10mA, 0.75V @ 100mA
> >
> > diode-ORing them followed by an LDO 3.3V regulator perhaps
>
>Thank you:
>yes a LDO would be better, have considered it.
>
>Actually, the slight variations in the load (which should actually
>always be in the range 250-350mA), should allow for a 1N4007 diode.

I would suggest this is not prudent-- you *could* get flaky Ethernet
performance if the analog circuitry internal to the ENC does not have a
well-regulated supply. IIRC, only the digital circuitry has an internal
regulator.

>Best regards,

Spehro Pefhany --"it's the network..."            "The Journey is the reward"
speff@interlog.com             Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog  Info for designers:  http://www.speff.com



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