Lpc2000

At 06:10 PM 1/7/06 -0500, Robert Adsett wrote:
>At 02:29 PM 1/7/06 -0500, Tom Walsh wrote:
> >Pieter Verstraelen wrote:
> >
> > >Hello all,
> > >
> > >a hardware related question: the LPC2210 has a dual power supply: 1.8V
> > >core voltage and 3.3V for the I/O.
> > >Is the power-on (and power-off) sequence of these 2 voltages critical?
> > >Will a 1.8V regulator behind the 3.3V regulator do the job? The 1.8V
> > >will be a little bit later during power-on.
> > >
>
><snip>
>
> >I use a 3.3v regulator feeding a seperate 1.8v regulator.  So, the 1.8v
> >stabilizes before the 3.3v and the 3.3v dies before the 1.8v.  The 1.8v
> >is feeding the ARM core and the 3.3v is for the external logic
> >interface. Following logical flow of the powerup / power down sequencing
> >of supplies would be that the 1.8v core would be active before and after
> >the 3.3v stabilization / decay.  I would suspect, that internally
> >reverse biasing the 1.8v core via the 3.3v could be a "bad thing"?  :-P
>
>Experimentally I've powered the 2106 with large delays (on the order of a
>second or so)in both directions w/o any observable effect.  Both bring up
>the 3V3 before and after the 1V8 rail.  At one point philips_apps stated
>that there were no sequencing issues and that appears to be borne out in
>practice so far.
>
>I wouldn't deliberating bring them up on widely different timescales in
>production but I also would spend effort sequencing them.  I would,

Oops that's 'wouldn't spend effort sequencing them'

>however, put in a 'proper' power monitor chip on the reset line.
>
>There doesn't appear to be any sequencing issues at all.  I've even run the
>1V8 at 5V accidentally w/o observable effect although I wouldn't want to
>use that chip as a production chip.
>
>Robert
>
>" 'Freedom' has no meaning of itself.  There are always restrictions,   be
>they legal, genetic, or physical.  If you don't believe me, try to chew a
>radio signal. "  -- Kelvin Throop, III
>http://www.aeolusdevelopment.com/
>
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" 'Freedom' has no meaning of itself.  There are always restrictions,   be 
they legal, genetic, or physical.  If you don't believe me, try to chew a 
radio signal. "  -- Kelvin Throop, III
http://www.aeolusdevelopment.com/