9 Evaluation Board Component Selection

This section describes the design process for the LM27402 evaluation board. Unless otherwise indicated, all formulae assume units of the following:

• Amps (A) for current
• Farads (F) for capacitance
• Henries (H) for inductance
• Volts (V) for voltage

The first equation to calculate for any buck converter is duty ratio:

Equation 1.

Due to the resistive powertrain losses, the duty ratio will increase based on the overall efficiency, η. Setting η = 1 yields an approximate result for D.