To achieve the highest regulation accuracy over wider load range, the user should target to create 50-mV of V_CS at full current. Therefore, R_CS should be selected as Equation 47:

Equation 47.

Ideally, a 1.5-mΩ current sense resistor should be chosen for this example. However, owing to availability, a standard non-inductive 1-mΩ current sense resistor is selected, namely,

Equation 48.

Because R_CS conducts the same current as the power inductor, its power dissipation is also determined by I_{Lm_RMS}.

If the selected R_CS has parasitic inductance (assuming it is 1 nH), it should be compensated, and the compensation capacitor C_CS should satisfy Equation 37.

Equation 49.

Select the closest standard capacitor, C_CS = 0.47 µF.

For optimal performance, it is good practice to add a 100-pF ceramic capacitor at each current sense pin to filter out common-mode noise, as shown in Figure 9-9.

Figure 9-9 Current Sense With Compensation to Cancel the Effects of Parasitic Inductances