The inductor value affects the peak-to-peak ripple current, the PWM-to-PFM transition point, the output voltage ripple, and the efficiency. The selected inductor has to be rated for its DC resistance and saturation current. The inductor ripple current (ΔIL) decreases with higher inductance and increases with higher VIN or VOUT and can be estimated according to Equation 1.
Equation 2 calculates the maximum inductor current under static load conditions. The saturation current of the inductor must be rated higher than the maximum inductor current, as calculated with Equation 2, which is recommended because during a heavy load transient the inductor current rises above the calculated value. A more conservative way is to select the inductor saturation current according to the high-side MOSFET switch current limit, ILIMF.
Table 9-2 shows a list of possible inductors.
|Inductance [µH]||Inductor Series||Size Imperial (Metric)||Dimensions L × W × T||Supplier(1)|
|0.47||DFE18SAN_G0||0603 (1608)||1.6 mm × 0.8 mm × 1.0 mm maximum||Murata|
|0.47||HTEB16080F||0603 (1608)||1.6 mm × 0.8 mm × 0.6 mm maximum||Cyntec|
|0.47||HTET1005FE||0402 (1005)||1.0 mm × 0.5 mm × 0.65 mm maximum||Cyntec|
|0.47||TFM160808ALC||0603 (1608)||1.6 mm × 0.8 mm × 0.8 mm maximum||TDK|
|1.0||DFE201610E||0806 (201610)||2.0 mm × 1.6 mm × 1.0 mm maximum||Murata|