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Atmega8L using 3v Battery

jackorocko

Apr 4, 2010
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http://www.atmel.com/dyn/resources/prod_documents/doc2486.pdf

• Operating Voltages
– 2.7V - 5.5V (ATmega8L)

• Power Consumption at 4Mhz, 3V, 25°C
– Active: 3.6mA
– Idle Mode: 1.0mA

http://panasonic.com/industrial/includes/pdf/Panasonic_Lithium_CR2032_CR2320.pdf

Looking at the datasheet for the battery (second graph), @50% capacity the V would be less then the operating voltage of your MC@2mA of current, so it would be worse for the [email protected]

Looking at the third graph, the capacity of the battery would be only about 100mAh at around 2mA, your situation would be worse.

So in theory, it might be able to run the Atmega8L for a very short time, I would think about ~10 hours if you was lucky(you would have to be really lucky, odds are this is unattainable) at full load of the Atmega8L. If you are unlucky, a lot less.
 
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OLIVE2222

Oct 2, 2011
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Hi,

The are way's to improve the battery live.
jackorocko estimation's applies for a continuous usage. But, depending of your application you can:

-Wake-up your circuit at fixed interval with a timer to have maybe few % of active current (discontinuous usage).
-Add a large (low leakage current) capacitor to limit battery peaks and so increase is life.
(this is almost the trick applied on some TV remote control where they are IR led currents peaks)
-Reduce the atmega clock as low as possible for your application (32Khz can be already enough)

Sure the battery life will not become years, but it's can help.

Olivier
 

[email protected]

Dec 29, 2010
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@ jackorocko : I finally ran atmega8L on cr2032 batteries and they actually ran for more than 20 hrs without any battery saving optimizations told by OLIVE2222. I believe the battery saving optimizations would help even more to extend the continuous usage time.
 

jackorocko

Apr 4, 2010
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I finally ran atmega8L on cr2032 batteries and they actually ran for more than 20 hrs without any battery saving optimizations told by OLIVE2222

don't blame me, the datasheets lied. To be honest, the datasheets give worse case scenarios, the uC probably consumed less power then its max is my guess.

Did you read your battery voltage when you where at 20 hours? What did you do with the uC for those 20 hours, was it in idle mode?
 
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