Lpc2000

Vol ??? You do mean Vih, don't you? In my experience I've never had a 
problem with driving 5V logic from 3.3V as the minimum Vih in is 
specified for full-speed digital switching. The 3.3V definitely drives 
the 5V logic as a logic high but it may not work to "parametric" 
specification at 100Mhz etc. For all your normal I/O work it is never a 
problem and I don't let myself lose sleep over it.

You can though for peace of mind and sleep use pull-up resistors to +5V 
on the output lines and simply simulate open-drain drivers by writing 
the IODIR. It doesn't matter if you initially drive them to 3.3V and 
then float by switching to inputs with the pull-up. IMO, skip the 
buffers, they are always overkill.

my2cents
*Peter*

p.s. Hey Rob! I dug out the TI yellow bible and mine is dated 1988. I 
also remember my first logic data book, it was a big red Fairchild 
Semiconductor TTL data book from the early '70s. Back then you needed 
PSUs that could supply amps, none of this itsy-bitsy pencell battery 
stuff! Plus you had to worry about fanout (both the blower type and 
driving type).


javida13 wrote:

>I have a 5 volt logical display that I'm driving.  The Vol for this 
>part is 3.5 volts (.7*Vcc).  I have 3-signals that must be driven to 
>this logic level.  Is there a LS type of device that can be used as the 
>level translator, where is can be powered by 5 volts and its input 
>level can be driven by 3.3 volt logic? 
>