Lpc2000

Sorry, could not fully understand your question. 
I was suggesting extra external hardware WDT to Mr Andrew Berney as
there might be cases of CPU not starting up, even with H/W 
reset/power supervisor.  His type of working condition is just too
tough for the CPU.

If external hardware WDT is installed, this type of hardware WDT are
normally cleared by reset (Power supply below threshold level) and
will start to "WDT ticking" only after the reset (Power is above
threshold level + some reset delay).   It will always ensure some
fixed WDT timeout after reset before that WDT "bites" (typically 1-2
seconds).

For the core voltage delay, it is the duty of the reset/power
supervisor chip to have enough extra reset delay, typical 50-200mS 
(extra reset delay after 3.3V power good to be longer than your 1.8V
LDO ramp delay)

Regards

--- In lpc2000@yahoogroups.com, "lpcarmed" <lpcarmed@...> wrote:
>
> I had startup issues when the power supply did not ramp up the 
voltage
> fast enough. The reset supervisor will make sure you reached the
> operating voltage and then apply the delay. If your CPU is locked 
up
> in a slow startup of the core voltage when peripheral supply 
already
> applied the watchdog might not work. Is there a specification for
> these conditions?
> 
> --- In lpc2000@yahoogroups.com, "unity0724" <unity0724@> wrote:
> >
> > Wow, very tough working condition for that Arm Chip...    
> > and interesting...  :)
> > 
> > May be you should use both power supervisor/monitor chip + 
external
> > Hardware WDT. => WDT "kicks" the CPU again if it does not power 
up
> > properly.
> > 
> > I've seen some AVR chips flash program-able for WDT always on 
after
> > reset.  (WDT default as on after reset)
> > 
> > Could you help eMail me your experience after the project??
> > Thanks in advance!
> > Regards
> > 
> > 
> > --- In lpc2000@...m, "Andrew Berney" <amb@> wrote:
> > >
> > > Hi all,
> > > 
> > > We're currently in the process of putting together a device 
that 
> > will be
> > > powered via an induction ring and as such there is the 
potential 
> > for the
> > > device to lose sufficient power intermittantly.
> > > 
> > > I was wondering on peoples' general opinion of using an 
external 
> > supervisor
> > > chip to ensure a clean startup by keeping reset pulled to 
ground 
> > for a
> > > period of around 150 milliseconds.
> > >
> >
>