ClarityHow to use this tool
- Enter maximum junction temperature, ambient temperature, dissipated power, junction-to-case resistance, case-to-sink resistance.
- Select Calculate to view the result.
- Check the method and assumptions below before using the result.
The method, explained
Allowed sink-to-ambient resistance = (Tj−Ta)/P−Rθjc−Rθcs.
Using maximum junction temperature = 125 °C, ambient temperature = 40 °C, dissipated power = 10 W, junction-to-case resistance = 2 °C/W, case-to-sink resistance = 0.5 °C/W, the result is 6 °C/W. Change these example inputs to match your task; use the method above to check each step.
Understanding your result
Steady-state lumped model. Airflow, orientation, transient peaks and interface quality affect real temperatures.
What to keep in mind
Steady-state lumped model. Airflow, orientation, transient peaks and interface quality affect real temperatures. Ideal-component calculation for study and estimation. It does not select safe wiring, protective devices or component ratings for an installation.
Common questions
How do I use this heat sink thermal resistance calculator?
Estimate the maximum sink-to-ambient thermal resistance allowed by a thermal budget. Enter maximum junction temperature in °C, ambient temperature in °C, dissipated power in W, junction-to-case resistance in °C/W, case-to-sink resistance in °C/W. The starting example is editable; use values for the same system or project.
Which assumptions affect this result?
Steady-state lumped model. Airflow, orientation, transient peaks and interface quality affect real temperatures.
Methodology maintained by ClarityKit. How these tools are built and checked.