Getting the clean current sense voltage with Parasitic Inductance in current sense resistor – Low side current sensing

Thread Starter


Joined Nov 28, 2012
we are evaluating MIC21LV32 from microchip in one of our applications.

For the current sensing we have used 3mΩ sense resistor(1206,1%,1W), as these sense resistors have higher ESL+ parasitic inductance in PCB. During testing with R1=R3=100Ω, No C2,C3,C4, we are seeing large spikes on CSP-CSN nodes.

My question is, for the current sense filter circuit (R1, R3, C2, C3, C4) below,

how can I decide the values of Input filter components (R1, R3, C2, C3, C4) so, that I can get clean voltage across 3mΩ resistor alone even though ESL present.

Below is the simulated circuit.


Below is the response of the circuit.

I have chosen Common mode filter values (R1, R3, C3, C4) and, Differential mode filter values (R1, R3, C2) randomly.

With same values I have done testing, but I do not see such improvement in the captured waveforms. Simulation to Actual HW only difference is AGND & DGND are connected at one place(near thermal pad), in simulation i have shorted it directly.

How can i go systematically to improve the response of the circuit?