Lpc2000

to Q1: in my opinion 5V tolerant means 5V tolerant within the full spec. But 
I am not Philips insider, so I don't know any life time lack with this 
assumption. I use it that way...

to Q2: it seems to me ok with the restriction that you won't have the full 
speed of the output because the RC of the pullup and the C of the load. It 
stays in any case faster then a ULN2003! And obviously you software port 
modell shoud be set on open-drain.

to Q3: I sugest you to reduce from 5V to 3.3V with a simple resistor 
attenuator. I prefer this solution because also in case of transients, the 
ADC voltage newer get any peaks higher then 3.3V. Overvoltages may produce 
crosstalk between ADCs. A second positiv effect is that a R load to a sensor 
amplifier forces the opamp to work in class A. I experienced better response 
with small signals.

to Q4: sorry, no idea

Kurt


>From: "dijucthat" <bigdaddy81@...>
>Reply-To: lpc2000@yahoogroups.com
>To: lpc2000@yahoogroups.com
>Subject: [lpc2000] 5v system integration
>Date: Wed, 15 Mar 2006 18:06:14 -0000
>
>I have a project that was setup for a 5v AVR that I would like to
>convert to an LPC2294.
>
>Q1: Is it better to use a simple voltage divider on the GPIO Input (to
>get 3.3v) or should I leave it at 5v? (I know it says 5v "tolerant",
>but is it safer at 3.3v)
>
>Q2: On GPIO outputs, can I use a pullup to get 5v, or should I use a
>buffer, ULN2003, etc.? (again, I am concerned with reliability)
>
>Q3: On the sensors designed for 5v operation, is an op-amp with gain
><1 the best solution to achieve 0-3.3 scale?
>
>Q4: On the ADC inputs, I have read that you should ues pullups even if
>they are not in use.... does this apply to all LPC?
>
>Thank you very much for any response!
>   Daniel.
>
>
>