Calculadora de Resistência Térmica
Calcule a resistência térmica para dimensionar a dissipação de calor em componentes eletrônicos.
Junction Temperature
85.0 °C
Junction Temperature vs Power Dissipated
Formula
## 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)
Exemplo Resolvido
5 W dissipation, theta_jc=3, theta_cs=1, theta_sa=8 C/W, 25C ambient.
- 01Total theta = 3 + 1 + 8 = 12 C/W
- 02T_junction = 25 + 5 x 12 = 85C
- 03T_case = 25 + 5 x 9 = 70C
Perguntas Frequentes
Where do I find theta_jc?
In the component datasheet under thermal characteristics. It depends on the IC package.
What is theta_cs?
Thermal resistance of the interface between IC case and heat sink. Thermal paste: 0.2-1 C/W. Bare contact: 1-3 C/W.
How accurate is this model?
It is a simplified steady-state model. Real systems have transient thermal behavior and non-uniform heat distribution.
Aprender