Lpc2000

On Fri, 05 Mar 2004 13:22:37 +0000, Alaric B Snell 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
=====================================================================
IDT <www.idt.com> make a product line called QuickSwitch which uses
this technique.  They are bi-directional and fast.

Regards
-Bill Knight
R O SoftWare