Lpc2000

--- In lpc2000@yahoogroups.com, "onceinfour" <mmack287@h...> wrote:
> Owen,
>     Thanks for advice re using mosfets instead of UDN2981.  I think 
> you will find thought that the Mosfet solution could not compete on 
> price, or reliability either with a dedicated solenoid driver which 
> the UDN2981 is.  We use 24V to power solenoids.  Still interested
in 
> Mosfet circuits.
>     My next problem is to guarantee that the drivers come up in the 
> off state after power-up.  i.e. need to ensure the i/p's remain low 
> until the micro is running and sets up states correctly.  On
LPC2xxx 
> gpio pins are initialised as inputs, so presumably I need
pull-downs 
> on each pin.  Not very elegant!

What is wrong with pull downs?  That seems very simple to me.  

But with this chip, unlike TTL, I think you don't need a pulldown. 
The circuit looks to me like it needs to be pulled up somewhat stiffly
(~0.25 mA @ 3.3 volts) to turn on, so a high impedance LPC output
would leave the driver off by default.