Data Sheet

LT8277

analog.com

Rev 0

16 of 31

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Inductor Selection

Select inductors with a saturation current higher than the programmed inductor current limit with some margin. The

inductance requirements will change based on switching frequency, programmed current limit, and input voltage.

Use Equation 1 to estimate the inductance needed for each phase. Additional margin is recommended.

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If parallel RC current sensing is to be used, be sure to select an inductor with reasonable limits on its equivalent

series resistance. A table of manufacturers appears in Table 6.

Table 6. Recommended Inductor Vendors

NAME

WEBSITE

Wurth Elektronik

www.we-online.com

TDK

www.tdk.com

Vishay

www.vishay.com

Coilcraft

www.coilcraft.com

Input Capacitor Selection

The input capacitor supplies transient current to the part and power stage. The X7R type ceramic chip capacitor is

often the best choice. Choose capacitors with a voltage rating around 60% higher than the maximum input voltage

the part will see. For a boost or SEPIC converter, the input capacitor can often be smaller than the output capacitor.

Use Equation 2 to choose an input capacitor. This relationship assumes that the inductor was selected using the

above guidance. Here, n represents the number of phases. Additional margin is recommended.

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The current flowing in the input capacitor of a boost converter is typically lower than the current flowing in the output

capacitor. A normalized plot of peak-to-peak current flowing in the input capacitor appears in Figure 29.

Normalized to:

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