I need to sense the current of a target MCU through various periods of its on/sleep/off state and then need to send this data back to another interface MCU to read out the value. They will be both on the same board, powered by 5 V USB.
However these are the requirements I have:
- 5 V USB PSU
- Must be able to sense currents in the range of nA to mA with high accuracy/precision. (I figure 1 nA to 500 mA)
- Only measure the current of the target MCU and not the interface.
- Must output maximum 3.3 V interface MCU
I have looked at available options and current sense amplifiers by Texas Instruments can't sense nA due to higher bias currents. So therefore I feel I would need a precision amplifier.
However I am stuck on how to proceed with this because, I need to somehow have a automatic dynamic current range and I am fairly new to current sensing and am not really sure on all the specifics.