Inductor Temperature Rise

ΔT = Ploss · Rth

Quick answer

This calculator solves ΔT = Ploss × Rth for Temperature Rise. With Total Loss 10 W, Thermal Resistance 20 °C/W, the result is 200 °C. It solves in 3 directions, so you can enter the values you have and get the one you need.

Calculator

Temperature Rise (°C)
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Formula

ΔT = Ploss × Rth

Description

An inductor’s temperature rise above ambient equals its total power loss (copper plus core) times its thermal resistance to the surroundings. Manufacturers often specify a rated current as the value that produces a fixed temperature rise (typically 40 °C). Checking the actual loss against the part’s thermal resistance ensures the inductor stays within its temperature limit at the real operating point.

Variables

  • ΔT — Temperature rise above ambient (°C)
  • Ploss — Total power dissipated (copper + core) (W)
  • Rth — Thermal resistance to ambient (°C/W)

Practical Notes

Datasheet "rated current (temp rise)" is derived from this. Core loss adds to copper loss; at high ripple the core term can dominate and must be included in Ploss.

Symbols and units

Symbol Meaning Default unit Accepted units
dT Temperature Rise °C °C
Ploss Total Loss W µW, mW, W, kW
Rth Thermal Resistance °C/W °C/W

Step by step

  1. 1. What you know: Total Loss 10 W, Thermal Resistance 20 °C/W
  2. 2. The relation: ΔT = Ploss × Rth
  3. 3. Substitute: Ploss = 10 W, Rth = 20 °C/W
  4. 4. Result: Temperature Rise = 200 °C

Worked examples

Minimum range

Given: Total Loss 10 mW, Thermal Resistance 0.1 °C/W

Result: Temperature Rise = 0.001 °C

Low range

Given: Total Loss 100 mW, Thermal Resistance 1 °C/W

Result: Temperature Rise = 0.1 °C

Typical

Given: Total Loss 10 W, Thermal Resistance 20 °C/W

Result: Temperature Rise = 200 °C

High range

Given: Total Loss 1 kW, Thermal Resistance 100 °C/W

Result: Temperature Rise = 100000 °C

Maximum range

Given: Total Loss 10 kW, Thermal Resistance 1000 °C/W

Result: Temperature Rise = 1 × 10⁷ °C

Solving for each variable

Solve for Temperature Rise

Total Loss 10 mW, Thermal Resistance 0.1 °C/W → 0.001 °C

Solve for Total Loss

Temperature Rise 2.5 °C, Thermal Resistance 0.1 °C/W → 25 W

Solve for Thermal Resistance

Temperature Rise 2.5 °C, Total Loss 10 mW → 250 °C/W

How Temperature Rise changes with Total Loss

Total Loss (input) Temperature Rise (result)
1 W 20 °C
2.5 W 50 °C
5 W 100 °C
7.5 W 150 °C
10 W 200 °C
15 W 300 °C
20 W 400 °C
40 W 800 °C
70 W 1400 °C
100 W 2000 °C

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Frequently asked questions

How do you calculate Inductor Temperature Rise?

Use ΔT = Ploss × Rth. With Total Loss 10 W, Thermal Resistance 20 °C/W, Temperature Rise works out to 200 °C.

What is the formula for Inductor Temperature Rise?

The formula is ΔT = Ploss × Rth. An inductor’s temperature rise above ambient equals its total power loss (copper plus core) times its thermal resistance to the surroundings.

How do you find Total Loss when you know the other values?

Rearrange for Total Loss: with Temperature Rise 2.5 °C, Thermal Resistance 0.1 °C/W, Total Loss is 25 W.

How do you find Thermal Resistance when you know the other values?

Rearrange for Thermal Resistance: with Temperature Rise 2.5 °C, Total Loss 10 mW, Thermal Resistance is 250 °C/W.

Related Concepts

All Inductors formulas →
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