Boost Inductor Value
L = Vin·(Vout−Vin) / (ΔIL·fs·Vout)
Quick answer
This calculator solves L = Vin × (Vout − Vin) / (ΔIL × fs × Vout) for Inductance. With Input Voltage 12 V, Output Voltage 26.4 V, Ripple Current 20 mA, Switching Frequency 100 kHz, the result is 3.273 mH. It solves in 3 directions, so you can enter the values you have and get the one you need.
Calculator
Formula
Description
This sizes the inductor of a boost (step-up) converter for a target peak-to-peak ripple current. The ripple is set by the volt-seconds applied to the inductor during the switch on-time, which depends on the input/output voltage ratio and the switching frequency. A larger inductor or higher frequency reduces ripple at the cost of size or switching loss.
Variables
- L — Inductance (H)
- Vin — Input voltage (V)
- Vout — Output voltage (V)
- ΔIL — Target peak-to-peak ripple current (A)
- fs — Switching frequency (Hz)
Practical Notes
A common design target is ΔIL ≈ 20–40% of the average inductor current. The inductor must not saturate at the peak current Iout/(1−D) + ΔIL/2.
Symbols and units
| Symbol | Meaning | Default unit | Accepted units |
|---|---|---|---|
| L | Inductance | µH | nH, µH, mH, H |
| Vin | Input Voltage | V | pV, nV, µV, mV, V, kV |
| Vout | Output Voltage | V | pV, nV, µV, mV, V, kV |
| dIL | Ripple Current | mA | pA, nA, µA, mA, A, kA |
| fs | Switching Frequency | kHz | Hz, kHz, MHz, GHz |
Step by step
- 1. What you know: Input Voltage 12 V, Output Voltage 26.4 V, Ripple Current 20 mA, Switching Frequency 100 kHz
- 2. The relation: L = Vin × (Vout − Vin) / (ΔIL × fs × Vout)
- 3. Substitute: Vin = 12 V, Vout = 26.4 V, dIL = 20 mA, fs = 100 kHz
- 4. Result: Inductance = 3.273 mH
Related quantities from the same inputs
- P = V × I = 0.24 W
Nearest standard component values
| Series | Nearest value | Error |
|---|---|---|
| E12 | 3.3 mH | 0.83% |
| E24 | 3.3 mH | 0.83% |
Worked examples
Minimum range
Given: Input Voltage 0.33 V, Output Voltage 0.726 V, Ripple Current 100 µA, Switching Frequency 100 Hz
Result: Inductance = 18 H
Low range
Given: Input Voltage 3.3 V, Output Voltage 7.26 V, Ripple Current 1 mA, Switching Frequency 1 kHz
Result: Inductance = 1.8 H
Typical
Given: Input Voltage 12 V, Output Voltage 26.4 V, Ripple Current 20 mA, Switching Frequency 100 kHz
Result: Inductance = 3.273 mH
High range
Given: Input Voltage 0.23 kV, Output Voltage 0.506 kV, Ripple Current 0.5 A, Switching Frequency 0.5 MHz
Result: Inductance = 0.5018 mH
Maximum range
Given: Input Voltage 2.3 kV, Output Voltage 5.06 kV, Ripple Current 5 A, Switching Frequency 5 MHz
Result: Inductance = 50.18 µH
Solving for each variable
Solve for Inductance
Input Voltage 0.33 V, Output Voltage 0.726 V, Ripple Current 100 µA, Switching Frequency 100 Hz → 18 H
Solve for Ripple Current
Inductance 100 nH, Input Voltage 0.33 V, Output Voltage 0.726 V, Switching Frequency 100 Hz → 18 kA
Solve for Switching Frequency
Inductance 100 nH, Input Voltage 0.33 V, Output Voltage 0.726 V, Ripple Current 100 µA → 18 GHz
How Inductance changes with Input Voltage
| Input Voltage (input) | Inductance (result) |
|---|---|
| 1.2 V | 0.5727 mH |
| 3 V | 1.33 mH |
| 6 V | 2.318 mH |
| 9 V | 2.966 mH |
| 12 V | 3.273 mH |
| 18 V | 2.864 mH |
| 24 V | 1.091 mH |
The same result in other units
| Unit | Value |
|---|---|
| nH | 3273000 |
| µH | 3273 |
| mH | 3.273 |
| H | 0.003273 |
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<p><a href="https://vbatpower.com/formulas/boost-inductor-value/">Boost Inductor Value</a> Calculator by vbatpower.com</p>Frequently asked questions
How do you calculate Boost Inductor Value?
Use L = Vin × (Vout − Vin) / (ΔIL × fs × Vout). With Input Voltage 12 V, Output Voltage 26.4 V, Ripple Current 20 mA, Switching Frequency 100 kHz, Inductance works out to 3.273 mH.
What is the formula for Boost Inductor Value?
The formula is L = Vin × (Vout − Vin) / (ΔIL × fs × Vout). This sizes the inductor of a boost (step-up) converter for a target peak-to-peak ripple current.
How do you find Ripple Current when you know the other values?
Rearrange for Ripple Current: with Inductance 100 nH, Input Voltage 0.33 V, Output Voltage 0.726 V, Switching Frequency 100 Hz, Ripple Current is 18 kA.
How do you find Switching Frequency when you know the other values?
Rearrange for Switching Frequency: with Inductance 100 nH, Input Voltage 0.33 V, Output Voltage 0.726 V, Ripple Current 100 µA, Switching Frequency is 18 GHz.
What units does Boost Inductor Value use?
Inductance is shown in nH, µH, mH, H. Values are held in SI base units internally, so you can mix prefixes without converting by hand.
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