Junction Temperature

Steady-state junction temperature and heat-sink sizing for power semiconductors via the θjc → θcs → θsa thermal-resistance chain

Operating Point

W
°C
°C

Package & Sink

K/W
K/W

Thermal Interface

W/(m·K)
mm²
K/W
Design looks good
Within Rating
84.2
Junction Temperature (°C)?
35.8
Headroom Below Derating (°C)?
17.17
Required θsa at Derated Limit (K/W)?
ambientdiecaseTIMPTj 84.2°CTc 76.7°CTs 75.0°CTa 25.0°C

Results

Junction Temperature(Tj)?
84.2°C
Case Temperature(Tc)
76.7°C
Sink Temperature(Ts)
75.0°C
Total Thermal Resistance(θtotal)
11.833K/W
Case-to-Sink Resistance(θcs)
0.333K/W
Required θsa at Derated Limit(θsa_req)?
17.17K/W
Required θsa at Abs Max(θsa_abs)?
23.17K/W
Derated Tj Limit(η·Tj_max)?
120.0°C
Headroom Below Derating(ΔT_derate)?
35.8°C
Max Power at Derated Limit(P_max)?
8.03W
Power Headroom(P_max/P − 1)?
60.6%

Junction Temp vs Power

Tj_maxη·Tj_max
P = 5 WTj = 84.2 °CTj_max = 150 °C

Created by Catlynn Nguyen & Jie Chai · 2026