Two methods for measuring current and what sense amplifier used are tackled in this app note from Texas Instruments. Link here (PDF)
Current is a signal that can provide valuable insight into how a system is operating. Under defined conditions, the amount of current required to perform a task is consistent, making the current information a useful indicator to determine if the system is operating within expectations. There are multiple measurement methods and locations where current is measured to evaluate this informative signal.
from Dangerous Prototypes https://ift.tt/2EIkdpA