I would like to add a differential amp to my battery current sensing. This is due to the resistor in the ground path being to large and creating a negative offset in my analog channels of my data acquisition product. This battery charge IC (DS2715) senses voltage for charging via this resistor in one direction and discharging when the current flow reverses. This has me worried that I may need a negative rail for the amp I'm trying to add in. I would really like to avoid adding yet another power supply especially just for this amp. So I guess my questions are as follows.
1. What low power amp (the bandwidth needs are very low - I'm assuming full differential is required) would be recommended. I was looking at the AD8476 amp.
2. Would I need a negative power supply to handle both polarities (created by charging and discharging)?
3. If the polarity switching is an issue could I just push the dc offset up instead of having a negative supply?
I"m just looking for some general guidance on how to implement one of your amplifiers into this circuit to help bring down that resistor R82. Anything comments are helpful. Schematics attached.