Lpc2000

--- In lpc2000@yahoogroups.com, "philips_apps" <philips_apps@y...> wrote:
> btw. the device will not be 100% pin compatible because we listen to
> all your guys inputs and improve our devices step by step. Single
> voltage supply and a 32 kHz input for the RTC are the two features
> that make pincompatibility impossible.
> 
> Regards, Robert

If you are going to add a 32 kHz crystal input for the RTC, it would
be very useful to make the RTC power independant of the rest of the
chip.  The Atmel AT91M55800A did this very well.  The RTC can be used
to control the power to the rest of the chip for timer based power
savings.  The RTC runs on a separate Vdd and can be powered by a Li
coin cell for years.  

I would also suggest that the PLL be designed so that the 32 kHz clock
can be the reference for the master clock PLL to save the need for a
second crystal or oscillator.  

These suggestions can save around $2 in system cost in a small
embedded system which is what your parts are targeted to.  

BTW, if you go to a single power voltage approach, which voltage will
it be, 3.3 or 1.8?  I don't understand how you can run the core from
3.3 volts and I don't understand how you can have 5 volt tolerant IO
(or 3.3 for that matter) with 1.8 volt powered IOs.  You're not
putting an LDO inside the chip are you?  That's one of the features
they use on the newest CPLDs that ruin their quiescent power ratings.