Tuesday 31 October 2017

microcontroller - Current sensing nA to mA


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:



  1. 5 V USB PSU

  2. Must be able to sense currents in the range of nA to mA with high accuracy/precision. (I figure 1 nA to 500 mA)


  3. Only measure the current of the target MCU and not the interface.

  4. 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.




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