Yahoo Groups archive

Lpc2000

Index last updated: 2026-04-28 23:31 UTC

Thread

RE: [lpc2000] Digest Number 856

RE: [lpc2000] Digest Number 856

2005-12-06 by Steve Franks

> 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

Re: [lpc2000] Digest Number 856

2005-12-06 by Mauricio Scaff

Well,

The only components that i have connected besides the processor are the 
reset circuitry (1 cap, 1 diode and 1 resistor), the RS232 driver 
(MAX3238), the regulator (MCP1701), the USB circuitry (now with 2 470K 
pulldown in the D+ and D- lines) , the crystal and pullups in 3 P0 pins.
Without the processor, the board consumes less de 2uA.



Steve Franks wrote:
> > 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
>
>
> SPONSORED LINKS
> Microprocessor 
> <http://groups.yahoo.com/gads?t=ms&k=Microprocessor&w1=Microprocessor&w2=Microcontrollers&w3=Pic+microcontrollers&w4=8051+microprocessor&c=4&s=93&.sig=tsVC-J9hJ5qyXg0WPR0l6g> 
> 	Microcontrollers 
> <http://groups.yahoo.com/gads?t=ms&k=Microcontrollers&w1=Microprocessor&w2=Microcontrollers&w3=Pic+microcontrollers&w4=8051+microprocessor&c=4&s=93&.sig=DvJVNqC_pqRTm8Xq01nxwg> 
> 	Pic microcontrollers 
> <http://groups.yahoo.com/gads?t=ms&k=Pic+microcontrollers&w1=Microprocessor&w2=Microcontrollers&w3=Pic+microcontrollers&w4=8051+microprocessor&c=4&s=93&.sig=TpkoX4KofDJ7c6LyBvUqVQ> 
>
> 8051 microprocessor 
> <http://groups.yahoo.com/gads?t=ms&k=8051+microprocessor&w1=Microprocessor&w2=Microcontrollers&w3=Pic+microcontrollers&w4=8051+microprocessor&c=4&s=93&.sig=1Ipf1Fjfbd_HVIlekkDP-A> 
>
>
>
> ------------------------------------------------------------------------
> YAHOO! GROUPS LINKS
>
>     *  Visit your group "lpc2000
>       <http://groups.yahoo.com/group/lpc2000>" on the web.
>        
>     *  To unsubscribe from this group, send an email to:
>        lpc2000-unsubscribe@yahoogroups.com
>       <mailto:lpc2000-unsubscribe@yahoogroups.com?subject=Unsubscribe>
>        
>     *  Your use of Yahoo! Groups is subject to the Yahoo! Terms of
>       Service <http://docs.yahoo.com/info/terms/>.
>
>
> ------------------------------------------------------------------------
>



[Non-text portions of this message have been removed]

Move to quarantaine

This moves the raw source file on disk only. The archive index is not changed automatically, so you still need to run a manual refresh afterward.