- Calculate the inductor Volt microsecond constant E × T (V × μs) with Equation 4.
Equation 4. where
- VSAT = internal switch saturation voltage = 0.9 V
- VD = diode forward voltage drop = 0.5 V
- Calculate the inductor Volt • microsecond constant (E × T) with Equation 5.
Equation 5. - 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.
Equation 6. E × T = 35.2 (V × μs)
- On the horizontal axis, select the maximum load current: ILOAD(max) = 0.5 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 35 (V × μs) horizontal line and the 0.5-A vertical line is 150 μH, and the inductor code is L19.
- Select an appropriate inductor from the four manufacturer's part numbers listed in Table 9-3.
From Table 9-3, locate line L19, and select an inductor part number from the list of manufacturers' part numbers.