Lpc2000

> Message: 22        
>    Date: Tue, 06 Dec 2005 16:56:45 -0200
>    From: Mauricio Scaff <scaffm@...>
> Subject: Re: Re: Still need help...
> 
> No, they are all pulled up or are outputs (outputting 0 in 
> port0 and 1 
> in port1).

If there is a path (impedance) from your pulled-up pins to ground, that can
suck power out the pullups - I've done it before.  Look very closely at the
leakage of things on the other end of the pin - some fet's I've used have
bad leakage specs - each sucks some number of uA from your pullup, you get
in trouble fast.  Since most devices have fet-inputs (being made of cmos)
you can get in trouble quickly.  Lots of devices (i.e. LDO regulators) used
to have really bad specs on their shutdown current too - I made a board with
some accelerometers that had to have pfets on their power-supply pins, even
thought they supposedly had disable capability - the spec'd 100uA of disable
current was eating most of my power budget!

Best,
Steve

Steve Franks, KE7BTE
Electrical & Firmware Engineer
Tucson Embedded Systems
(520) 575-7283 x171