频率与波长转换计算器 — 公式

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)

    • 计算示例

    5 W dissipation, theta_jc=3, theta_cs=1, theta_sa=8 C/W, 25C ambient.

    1. Total theta = 3 + 1 + 8 = 12 C/W
    2. T_junction = 25 + 5 x 12 = 85C
    3. T_case = 25 + 5 x 9 = 70C