Calculate the inductor Volt • microsecond constant E × T (V × μs), with Equation 4:
VSAT = internal switch saturation voltage = 1.16 V
VD = diode forward voltage drop = 0.5 V
Calculate the inductor Volt • microsecond constant
(E × T),
Use the E × T value from the previous formula and match it with the E × T number on the vertical axis of the Inductor Value Selection Guide shown in Figure 9-8.
E × T = 34.2 (V × μs)
On the horizontal axis, select the maximum load current.
ILOAD(max) = 3 A
Identify the inductance region intersected by the E × T value and the maximum load current value. Each region is identified by an inductance value and an inductor code (LXX). From the inductor value selection guide shown in Figure 9-8, the inductance region intersected by the 34 (V • μs) horizontal line and the 3-A vertical line is 47 μH, and the inductor code is L39.
Select an appropriate inductor from the manufacturers' part numbers listed in Table 9-1. From the table in Table 9-1, locate line L39, and select an inductor part number from the list of manufacturers part numbers.