Lpc2000

I'm using the TI TPS77733 for 3.3 volts and the TPS77118 for 1.8
volts.  Both have open-drain, delayed release, -RESET signals which I
tie together and pull-up with a 10K.  That signal is then connected to
the LPC -RESET input.  The 3.3v reg is a bit overkill but is also
powering a bunch of other stuff on the board.  Both are pretty
inexpensive and available from DigiKey.

-Bill Knight
R O SoftWare



On Sat, 28 Feb 2004 17:39:54 -0500, Robert Adsett wrote:

At 04:40 PM 2/28/04 +0000, you wrote:
>--- In lpc2000@yahoogroups.com, "vrrraju" <vrrraju@y...> wrote:
> > Dear Friends,
> >
> > I am trying to make an evaluation board for myself and later for
> > commercial purpose based on LPC2106. I have little doubts on reset
> > circuitry. I am planning to use a RC circuit of 10K and 100nF to
> > reduce the cost. Otherwise is it compulsory to use Reset IC for this
> > purpose. Please suggest me on this circuit.
> >
> > Thanks in advance.

>This is a tricky circuit depending on how well you want it to work.
>Most modern MCUs have a POR (power on reset) and BOD (brown out
>detect) built in.  I am surprised that the LPC parts don't.

I don't know about most.  The ones I've worked with in the past haven't.

I'd use a reset/supervisory circuit myself, they are inexpensive and small 
if you only monitor a single voltage.  I've not found an inexpensive 
multi-voltage monitor.  The closest I've found were some Maxim parts but 
they noted that they wanted minimum orders above 10K units.  You can get 
away with a single monitor if you monitor the voltage that is common to all 
of your voltages and are willing to take the chance that the lower voltages 
will be OK if the higher one is.

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





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