Please enter all required values.
Formulas & Mathematical Logic
Step 1: Convert inductance from µH to H: L(H) = L(µH) / 1000000.
Step 2: Maximum ON time: Tonmax = Isat × L / V.
Step 3: Minimum frequency: Fmin = 1 / (2 × Tonmax).
Step 4: Maximum power: Pmax = V × Isat / sqrt(6).
Step 5: Saturation energy: Esat = Isat × Isat × L / 2.
Step 6: Tonmax is displayed in µs, Fmin in kHz, Pmax in W and Esat in µJ.
Step-by-Step Example
Example: Voltage across inductor = 12 V, inductance = 100 µH, saturation current = 5 A.
Step 1: Convert inductance: 100 µH = 0.0001 H.
Step 2: Tonmax = 5 × 0.0001 / 12 = 0.0000417 s = 41.7 µs.
Step 3: Fmin = 1 / (2 × 41.7 µs) = about 12 kHz.
Step 4: Pmax = 12 × 5 / sqrt(6) = about 24.5 W.
Step 5: Esat = 5 × 5 × 0.0001 / 2 = 0.00125 J = 1250 µJ.
About This Calculator
Check inductor current ramp, saturation energy and power limit for switching circuits.
The CalcBoy Inductor Current and Maximum Power Calculator estimates maximum ON time, minimum frequency, maximum power and saturation energy from voltage, inductance and saturation current.
In switching power supplies, the inductor current does not jump instantly. It ramps upward based on the voltage across the inductor and the inductance value. If the switch remains on for too long, current can reach the saturation current rating. Once the core saturates, inductance drops sharply, current rises faster and MOSFETs, diodes, sense resistors or windings can be stressed.
This calculator is useful for buck converters, boost converters, flyback startup checks, pulse inductors, solenoid drivers, current ramp circuits, SMPS troubleshooting and coil energy estimation. The maximum ON time result helps compare PWM duty cycle or pulse width against the safe current ramp before saturation. The saturation energy result helps understand how much magnetic energy is stored at the rated saturation current.
Use the result as an engineering estimate. Real designs also depend on DCR, temperature, ripple current, switching losses, core material, saturation curve shape, PCB copper temperature and current sense behavior.
Best UseInductor current ramp and saturation checks.
Supported InputsVoltage, inductance in µH and saturation current.
Helpful ForBuck, boost, flyback, SMPS, pulse coils and energy storage circuits.
Design ReminderKeep margin below saturation current, especially at high temperature.
Tip: Datasheet saturation current is often measured at a specific inductance drop percentage. Always check the test condition, not only the headline current rating.
Frequently Asked Questions
What is Ton Max?
Ton Max is the maximum switch on-time before inductor current reaches the saturation current estimate.
What is inductor saturation current?
It is the current where the magnetic core begins to saturate and inductance drops from its normal value.
Why does higher voltage reduce Ton Max?
Higher voltage makes inductor current rise faster, so it reaches saturation current in less time.
What does saturation energy mean?
It is the stored magnetic energy in the inductor at the saturation current level.
Can this be used for SMPS design?
Yes. It is useful for early buck, boost, flyback and pulse power checks, but final designs need datasheet and hardware verification.
Does this include resistance or core loss?
No. The original formula uses ideal inductor ramp and energy equations and does not include DCR, core loss or temperature effects.