Lpc2000

Please, need an element of practicality here.  We are talking about a 
lot of i/o lines, in our design we are looking at 3 x 8 way solenoid 
drivers, that's 24 signals.  Would make more sense to use a 3.3V to 
5V logic translator(s), but I am trying to save the board space and 
cost.
Michael.


--- In lpc2000@yahoogroups.com, Alaric B Snell <alaric@a...> wrote:
> onceinfour wrote:
> > I want to connect the LPC2114 (or other LPC2xxx) to 5V solenoid 
> > drivers (eg. UDN2981's).  Can I pull up the outputs of the LPC to 
5V 
> > with say 10K, to satisfy the input reqmts of the driver?
> 
> Hmmm. You might be able to do that with a diode, to prevent it from 
> back-feeding current into the internal 3.3v line from the 5v line 
when 
> it's trying to pull the line high.
> 
> On the other hand, there is a neat circuit to bidirectionally 
convert 
> between logic levels, I seem to recall... put a MOSFET between the 
3.3v 
> part and the 5v line (as in, drain to source) and connect the gate 
of 
> the FET to 3.3v, or somesuch. I found the circuit while googling 
for 
> ways of communicating between 3.3v and 5v I2C.
> 
> I'm planning on putting 5v pullups on the I2C lines from the LPC - 
but 
> they're pull-down-only, so that's meant to be OK.
> 
> > Michael.
> 
> ABS