Work out heat sink size instantly with clear inputs, formula shown and shareable results.
The thermal chain is junction to case, case to sink through the interface, then sink to ambient. Total allowable thermal resistance is the permitted temperature rise divided by the power, so the heat sink must supply whatever is left after subtracting the junction-to-case and interface resistances.
Thermal sizing
Rth(total) = (Tj(max) - Tambient) / P; Rth(sink) = Rth(total) - Rth(jc) - Rth(interface)
Electrical results are planning estimates only. Verify against the applicable wiring rules (IEC 60364, BS 7671, NEC or local code) and have all installation work designed and checked by a qualified electrician.
The device cannot dissipate that power at that ambient, no matter what sink is fitted. Reduce the power, use a better package, or add forced air or liquid cooling.
No. Derate to 80% or less of Tj(max) — reliability and lifetime fall roughly exponentially with junction temperature.