Circuit for review

bambino

I want to monitor the voltage of·my battery. It's a 7.2 volt·NIMH and fully charged it runs about 8.5 max.
I don't want a lot of accuracy, I just need to know when it's about to drop my 5 volt regulator.·And maybe judge what run time I have left.
I have put in a voltage·divider and was curious if·I had thrown off the adc circuits ability to measure the signal?.······

Thanks

Beau Schwabe

bambino,

Don't forget to take into account a 0.6V diode drop before figuring your voltage divider values.

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Beau Schwabe

IC Layout Engineer
Parallax, Inc.

bambino

Thanks Beau,
My display runs off of the 5V, so it's important to know about when to turn it off and sound a low bat warning or it will constantantly turn on and off with the battery charge!

Post Edited (bambino) : 6/16/2008 5:00:51 AM GMT

Rayman

I think you could also view your circuit as having a pull-down resistor to Vss...

I have a calculator for this case here:

http://www.pulsedpower.net/Applets/Electronics/SigmaDeltaADC/SigmaDeltab.html

william chan

Is the diode really necessary?
Don't forget that this circuit also adds to the drain of the battery.

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