Thermal Widerstand Rechner — Formel
## Thermal Resistance Chain
### Formula
**T_junction = T_ambient + P x (θjc + θcs + θsa)**
Thermal resistances add in series like electrical resistances. Each interface adds temperature rise per watt of dissipation.
- θjc: junction to case (from datasheet)
- θcs: case to heat sink (thermal pad/paste)
- θsa: heat sink to ambient (heat sink rating)
### Formula
**T_junction = T_ambient + P x (θjc + θcs + θsa)**
Thermal resistances add in series like electrical resistances. Each interface adds temperature rise per watt of dissipation.
- θjc: junction to case (from datasheet)
- θcs: case to heat sink (thermal pad/paste)
- θsa: heat sink to ambient (heat sink rating)
Lösungsbeispiel
5 W dissipation, theta_jc=3, theta_cs=1, theta_sa=8 C/W, 25C ambient.
- Total theta = 3 + 1 + 8 = 12 C/W
- T_junction = 25 + 5 x 12 = 85C
- T_case = 25 + 5 x 9 = 70C