I'm thinking about current sensing with a high dynamic range (10 mA - 20 A) and using LTC6102 as a high-side current sense amp (the voltage would be 54.6 V max, a 13S6P Li-ion battery).
The ADC I'm planning to use is LTC1407 (12-bit 1.5 MS/s).
I am planning to use OPA2365 as a unity-gain buffer between the current-sense amplifier and the ADC.
The current-sense amplifier provides an output current proportional to the sense voltage and given the high voltage and small package size, the output current has to be 1 mA full scale which requires a rather high value output resistor and thus a buffer is needed between the current-sense amplifier and the ADC.
The op-amp requires a small (-0.1 V) negative supply for the output to go down to 0 and it's important to go down to 0 in my case because of the high dynamic range I want.
I could try and do a negative supply e.g. a crude one with an additional battery between ground and the negative supply of the op-amp, but I would rather avoid it to simplify the circuit.
Is there a way that I can measure down to 0 without a negative supply voltage for the op-amp in this case?
I'm thinking of maybe putting a diode in series with the output resistor of the current-sense amp to offset the output voltage and then correct the scale of the ADC output accordingly, but I'm not sure if this will work. For low currents the diode would be in the region where small current changes would cause comparable voltage changes I suppose.