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'[PIC:] Finding the current hog...'
2004\05\19@115428 by Mike Hord

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I have a low power design that I'm trying to get as far down
as possible.  It sits at ~980 uA right now, but over 500 uA of
that is a "low power" op amp that I'm shopping for a
replacement for.

I've already gone through the PIC, minimized its current draw
as much as possible (pins not pulled externally are outputs,
being driven high or low).  The remaining ~440 uA still seems
a bit high, since everything on the board is shutdown but the
voltage regulator.  The sleep currents for the other
components on the board sum up to less than 200 uA.  Can
anyone give me some general troubleshooting advice to find
the hog that's sucking up the other 250 uA?

Mike H.

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2004\05\19@134522 by Bob Ammerman

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Place resistors in series with the power pins of the devices and measure the
voltage across them.

Bob Ammerman
RAm Systems

{Original Message removed}

2004\05\19@162343 by Jose Da Silva

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On Wednesday 19 May 2004 08:54, Mike Hord wrote:

>I've already gone through the PIC, minimized its current draw
>as much as possible (pins not pulled externally are outputs,
>being driven high or low).  The remaining ~440 uA still seems
>a bit high, since everything on the board is shutdown but the
>voltage regulator.  The sleep currents for the other
>components on the board sum up to less than 200 uA.  Can
>anyone give me some general troubleshooting advice to find
>the hog that's sucking up the other 250 uA?

PORTB Weak Pullups 250 typical
BrownOut 350uA typical
don't forget Watchdog takes current too.

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2004\05\19@163755 by Bob Axtell

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A/D Converter running? PORTB pullups on?

Any digital inputs between states (that one got ME once).

Scope the PIC pins while in the low power state to see if the "natural"
state of the pins without being driven is opposite to what you think it
is; could be pulling that 250uA that way.

I agree- 980uA seems too high to me as well. You could try the L parts,
they DO draw a lot less.

--Bob

Mike Hord wrote:
{Quote hidden}

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               Bob Axtell
       PIC Hardware & Firmware Dev
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