12v A2D circut with minimal power consumption

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What circuit and technique should I use for a lest power consuming design for 8 bit AVR measuring the charge of a 12V battery bank?

 

* Post your questions in the appropriate forum. The "AVR Freaks Projects" forum is for questions about existing, fully completed submissions in the "Projects" area. Moderator. *

Last Edited: Thu. Nov 22, 2018 - 01:07 AM
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One approach is to put a FET switch between the battery and the resistor voltage

divider that feeds the ADC input.  Switching it on to measure, then off, keeps current

consumption low. 

 

Here is a diagram for measuring a 9V battery:

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another example that's for a 4S Li-ion battery :

AVR1300: Using the AVR XMEGA ADC

(page 21)

via AN2535 AVR1300: Using the XMEGA ADC | Application Notes | Microchip Technology Inc. 

Adjust the source resistance as XMEGA can have a larger source resistance than megaAVR at a given sample rate.

 

Edit: source R

 

"Dare to be naïve." - Buckminster Fuller

Last Edited: Fri. Nov 23, 2018 - 07:16 PM
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I never posted a thank you for these circuits, Thank You! I have a related problem. I need a minimal power consumption AVR solution for 13.5-11V DC. Can I somehow beat the voltage divider method of powering this AVR? I want it to mostly sleep. 

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capnkeith wrote:
I need a minimal power consumption AVR solution for 13.5-11V DC.

Do you mean you need a voltage regulator for your project? 

One linear regulator I have used on past for a battery powered project was the TI LP2985, the quiescent current is only 95uA.

You may have even better results using a switching buck regulator, other freaks may be able to offer examples of these.

 

Good luck with the project.

 

Jim

 

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