Low side current sensing

 

• The above circuit senses the current flowing to the load.
• The sensing mechanism is low side sensing as the current flowing through the ground is sensed using sense resistor
• The current drawn by the operational amplifier is not sensed by the current sense circuit
• The operational amplifier is in inverting mode and the gain is R2/R3
• The voltage developed across the sense resistor is amplified by the operational amplifier circuit
• The output of operational amplifier is an analog voltage connected to the ADC of the micro controller
• Depending on the current to the load sense resistor need to be chosen
• The operational amplifier gain need to be chosen based on the analog input allowed to the micro controller
• If a single supply is desired for load and operational amplifier, Operational Amplifier selection depends on the supply to be provided to the load
• The operational amplifier quiescent current must be low
• For this kind of application, input offset voltage must be very low such that the circuit doesn't introduce undesired voltage