Is there anyway to get these links working again? They don't seem to be functional. Also, I'm assuming that the output of the voltage divider is unaffected by the capacitor.
So with a fully charged lithium ion batter (4.2V) you would expect to see a voltage of
4.2*(2.2/10) = .924V
Is the functionality of the circuit as follows? The capacitor is just acting to store up some charge to dump charge into the internal capacitor used by the ADC. It is essentially acting as a low impedance voltage source for the ADC sampling circuit?
Actually, the maximum voltage that is input to the ADC for this setup is approximately:
4.2V * (2.2M/(2.2M+10M))=0.76V
and the minimum voltage is approximately
2.7V * (2.2M/(2.2M+10M))=0.49V
Your assumption is correct, the capacitor charges up before sampling, and holds the voltage steady for adequate time during the sampling period. The voltage will of course drop a little bit but the capacitor is dimensioned so that discharging during the sampling period (68 microseconds)is less than what corresponds to 1 bit when sampling with 10-bit resolution, so the error is not noticable.
Actually, the maximum voltage that is input to the ADC for this setup is approximately:
4.2V * (2.2M/(2.2M+10M))=0.76V
and the minimum voltage is approximately
2.7V * (2.2M/(2.2M+10M))=0.49V
Your assumption is correct, the capacitor charges up before sampling, and holds the voltage steady for adequate time during the sampling period. The voltage will of course drop a little bit but the capacitor is dimensioned so that discharging during the sampling period (68 microseconds)is less than what corresponds to 1 bit when sampling with 10-bit resolution, so the error is not noticable.
