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dbotkin
Joined: 08 Sep 2003
Posts: 197
Location: Omaha NE USA
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 Posted: Fri Apr 23, 2004 7:58 am |
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Yes, you can turn on the comparator (or ADC, or whatever else you need) just while you need it, then turn it back off.
Bear in mind that the internal Vref is no more than a voltage divider referenced from Vdd... so the internal reference won't do you any good for detecting low battery. You'll need an external Vref.
Dale |
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willie.ar
Joined: 21 Jan 2004
Posts: 15
Location: Argentina
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| Posted: Tue Nov 06, 2012 12:59 pm |
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| PCM programmer wrote: | | Quote: | | Errrr, do I detect a hint of sarcasm? |
Actually it was mild exasperation. I know I shouldn't do it,
but sometimes I just give in to it. 
But truly, the current data sheet (Rev. C) for the 12F629/12F675
is a lot better in the Electrical section than the typical Microchip
data sheet. The typical data sheet has "TBD" or "Preliminary"
plastered all over the charts. The Rev. C data sheet has very
detailed charts for power consumption. For example, Tables
12-3 and 12-4 show the following values for 3.0v operation:
LP MODE: 18 ua
WDT: 1.8 ua
BOD: 58 ua
T1OSC: 4.6 ua
CVREF: 85 ua
COMP: 6.1
--------------
Total 173.5 ua
That list above explains most of the current draw that you're seeing.
There may be other peripherals that you have turned on, that I'm not
aware of. Also, the values given above are from the "Typical" column
in the chart. It also gives "Maximum" values, so one or more of the
numbers above could actually be higher. Then it would explain the
entire 190 ua that you're seeing.
This is why I was mildly bugging you to look at the data sheet.
It's because the answer is there. |
This is an interesting post and has abundant information.
I was trying to find what was draining so much current in sleep mode without success. After reading this post I found I left the BOD enabled. In my case, on a 12F675 @ 5 V consumption was 100 uA. After disabled it, input current can´t be read with my tester. Thanks for your contribution. |
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