Lpc2000

--- In lpc2000@yahoogroups.com, "lp2000c" <lp2000c@e...> wrote:
> 
> There's that little gotcha of these parts being 5V tolerant only 
when 
> 3.3V is present on the i/o supply.
> 
> Since in most designs with 5V and 3.3V, one would likely generate 
the 
> 3.3V from the 5V supply, there will likely be a period of time when 
> 5V is present and 3.3V is not.
> 
> Unless one adds a bunch of hardware to prevent this, it sort of 
makes 
> the 5V tolerant feature worthless.

Tip!

Run the regulators(zener+resistor+charge cap) in paralell,
(not in series)then use a larger charge cap on +5V or if
a variable regulator are used use a (voltage settling delay)
cap on adjust pin. It will also add for increased performance
by filtering noise on the adjust pin!

Or set every +5V external IC's in tristate at power on!! Urg!!

REG
KD