°C/W
Celsius degree per watt
Thermal resistanceexact by definition
The Celsius degree per watt is exactly equal to the kelvin per watt, and it is the form printed on every semiconductor and heatsink datasheet. A TO-220 package is about 62 °C/W junction to ambient in free air and 1 °C/W junction to case; the heatsink and interface make up the rest.
Watch out: Datasheet θJA figures are measured on a specified board in still air and are close to useless as an absolute prediction. Treat them as a comparison between parts, not as a design number.
| 1 °C/W | 1 K/W |
Solvers that use thermal resistance