Boost Converter Calculator

A boost converter is a switched-mode power supply that steps up an input voltage to a higher output voltage. The foundational relationship relies on the duty cycle (D), which represents the fraction of the switching period that the internal power switch remains closed. The basic voltage conversion formula assumes an ideal, lossless converter and is expressed as:

duty_cycle = 1 - (V_in / V_out)

To design the energy-storage component, we calculate the required inductance based on the allowable inductor ripple current (I_ripple) and the switching frequency (f_sw). The governing inductance formula is:

inductance = (V_in * duty_cycle) / (f_sw * I_ripple)

Let us walk through a practical scenario where you need to design a step-up power supply. Suppose your input voltage (V_in) is 12 V from a battery, and your target output voltage (V_out) is 24 V for a custom LED driver. Your chosen switching frequency (f_sw) is 100 kHz (100,000 Hz), and you want to keep the inductor ripple current (I_ripple) at 0.5 A.

First, calculate the duty cycle: duty_cycle = 1 - (12 / 24) = 1 - 0.5 = 0.5 (or 50%). Next, determine the minimum required inductance: inductance = (12 * 0.5) / (100,000 * 0.5) = 6 / 50,000 = 0.00012 H, which equals 120 µH. Selecting an inductor slightly above 120 µH ensures continuous conduction mode under these operating conditions.

Always choose an inductor with a saturation current rating significantly higher than your peak switch current to prevent core saturation and sudden efficiency drops. Keep high-frequency current loops as tight and short as possible on your printed circuit board to minimize electromagnetic interference (EMI) and voltage spikes. Finally, account for component parasitics, such as the equivalent series resistance (ESR) of output capacitors and diode forward voltage drops, which will slightly reduce your actual circuit efficiency compared to ideal theoretical models.