Inductor Temperature Rise

Formula

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.