Boost Converter Calculator — Duty Cycle, Inductance & Switch-On Time

Boost Converter Calculator

Our boost converter calculator is here to help you find the duty cycle and inductance of your circuit, characterizing your boost converter. Keep with us in this article to explore:

• What is a boost converter?
• How to make a boost converter?
• How do you choose the boost converter switching frequency?
• What is the difference between a boost converter and an inverter?
• What is the difference between a buck and a boost converter?
• How do you calculate the switch-on period for a boost converter?

So, let us step up your voltage with the boost converter calculator.

What is a boost converter? How do you make a boost converter?

The boost converter is an example of a DC-to-DC converter, which steps up the input DC voltage to a higher output DC voltage. It is also a class of the so-called switched-mode power supply (SMPS), which are electronic circuits that incorporate a switching regulator to convert electrical power efficiently.

They have several applications in battery-powered devices, power supplies, LED drivers, and electric vehicles.

A typical boost converter can be built using key components: an inductor, switch, diode, capacitors, and a control circuit. In a standard boost converter, C_in and C_out are the input and the output capacitors, L₁ is the inductor, D₁ represents the diode, Q₁ is a transistor working as a switch for the boost converter, and V_in and V_out are the input and the output voltages, respectively.

Components, duty cycle and inductance

This DC-to-DC converter can be characterized by computing the duty cycle and the inductance. The duty cycle measures how long the switch stays on relative to the total switching period. It can be determined using the formulas below:

• D = 1 − Vin / Vout
• D = Ton / Tsw

where:

• V_in — Maximum value of the input voltage;
• V_out — Output voltage measured at the end of the circuit;
• T_on — Period when the electronic switch is on; and
• T_sw — Period of the switching oscillatory cycle.

The duty cycle has a direct impact on the efficiency of the circuit. Basically, for low values of D, we have high efficiency at the cost of a low boost ratio (V_out/V_in). If we have high values of D, then we have low efficiency due to high conduction and inductor losses. Therefore, the ideal scenario is to have moderate values of D, optimizing the balance between the efficiency and the boost ratio.

Another relevant parameter to characterize the boost converter is the inductance, whose equation is:

L = Vin × (Vout − Vin) / (ΔIL × fsw × Vout)

where ΔI_L is the inductor ripple current and f_sw is the switching frequency. The ripple current ΔI_L is usually chosen as a fraction (typically 20–40%) of the average inductor current, which for an ideal (lossless) converter equals the input current I_in = I_out × V_out / V_in.

How do you choose the boost converter switching frequency?

The switching frequency is a design trade-off. A higher frequency lets you use a smaller inductor and smaller capacitors (saving size and cost), but it increases the switching losses in the transistor and diode, lowering efficiency. A lower frequency improves efficiency but requires bulkier magnetics. Most discrete boost converters operate between roughly 50 kHz and 1 MHz; integrated controllers often run from a few hundred kHz to a few MHz.

Boost converter calculator: an example

Suppose you want to step up a V_in = 5 V battery to V_out = 12 V, delivering I_out = 1 A at a switching frequency of f_sw = 50 kHz, and you target a 30% inductor ripple current. The calculator returns:

• Duty cycle: D = 1 − 5/12 ≈ 58.3%
• Input current: Iin = 1 × 12/5 = 2.4 A
• Ripple current: ΔIL = 0.30 × 2.4 = 0.72 A
• Required inductance: L = 5 × (12 − 5) / (0.72 × 50000 × 12) ≈ 81 µH

Enter your own values above to characterize any boost converter design.

FAQs

What is the difference between a boost converter and an inverter?
A boost converter is a DC-to-DC converter: it takes a DC input and produces a higher DC output. An inverter is a DC-to-AC converter: it takes a DC input and produces an AC output (for example, to run mains-powered appliances from a battery). Many practical inverters use a boost stage internally to raise the DC voltage before the DC-to-AC conversion.

What is the difference between a buck and a boost converter?
A buck converter steps the voltage down (V_out < V_in), while a boost converter steps the voltage up (V_out > V_in). In a buck converter the duty cycle is D = V_out/V_in, whereas in a boost converter it is D = 1 − V_in/V_out. A buck-boost converter can do both.

How do you calculate the switch-on period for a boost converter?
First compute the switching period T_sw = 1/f_sw, then multiply by the duty cycle: T_on = D × T_sw. For the example above, T_sw = 1/50 kHz = 20 µs and T_on = 0.583 × 20 µs ≈ 11.7 µs.

Can the output voltage be lower than the input voltage?
No. A boost converter can only step the voltage up, so V_out must be greater than V_in. If you need a lower output, use a buck (step-down) converter instead.

Measurement units

This calculator works with both the metric (SI) and American engineering unit systems. Electrical quantities — volts (mV, V, kV), amperes (mA, A), hertz (Hz, kHz, MHz) and henries (H, mH, µH, nH) — are identical in both systems, so no separate imperial conversion is required. This calculator performs no monetary calculations.