The first step in measuring current flow is to convert the electrical current into a more easily measured voltage parameter. Current shunt resistors are inexpensive components that accomplish this task.  Cost-effective shunt resistors surpass Hall sensor and become a more popular passive component for current sense, such as MMS8420 from Microhm Electronics.


However, the value of a shunt resistor should be low to minimize its impact on the circuit, and to minimize power dissipation in the resistor itself.

Other significant parameters for current shunt resistors include TCR and thermal EMF, both of which can significantly affect the current measurement accuracy.

Finally, to maximize measurement accuracy, it’s critically important to keep the high current flowing through the current sense resistor out of the sensing path, either by using a special printed circuit layout that creates a Kelvin connection for a two-terminal current sense resistor, or by using a four-terminal current sense resistor, like MVR2321-4, MVR3825-4 and MVR4618-4.

As a low resistance value means that the voltage developed across the current sense resistor will be small. Therefore, AFE is designed to amplify the low voltage into a larger one, allowing it to more easily be measured by an ADC.