Hi,

I need to measure the voltage of a battery, so i'm going to be using a resistor voltage divider to drop the voltage down to <5v that the ADC can handle. Like this:


Battery +ve ------- 18k Resistor ------- ADC Pin ------- 4.7k Resistor ------- Ground

My question is, what is my impedance for calculating the min ADC acquisition time in this instance? Is it just the impedance to ground (i.e. 4.7k)? Or do I have to consider the 18k resistor as well?