Thermal management

Sowmiya

Hi Team,

We are currently using the MOSFET C3M0040120J2-TR in our design and are in the process of selecting a suitable heat sink for thermal management.

We kindly request your support in:

• Recommending a compatible heat sink for this part
• Providing guidance on thermal design considerations (natural / forced cooling, mounting, etc.)

Additionally, our design conditions are approximately:

• Power dissipation: ~8–10 W
• Ambient temperature: ~60°C
• Cooling method: forced

Please suggest suitable heat sink part numbers or references based on the above conditions.

Forum_Moderator

Thank you for your post, it has been approved and we will respond as soon as possible.

SudharsanC

Hi Sowmiya,

Based on your design requirements:

Thermal requirements:

Temperature difference (junction to ambient): ΔT=175°C (max junction) −60°C (ambient)=115°C

Total allowable thermal resistance

RθJA (junction to ambient): = ΔT/ P =115/10 (power dissipation -worst case) = 11.5°C/W

The total thermal resistance from junction to ambient(RθJA) is the sum of all intermediate resistances along the heat flow path: RθJA=RθJC+RθCS+RθSAR

Where:

• RθJC: Junction-to-case thermal resistance
  • RθJC = 0.39 °C/W (from datasheet)
• RθCS: Case-to-heat sink resistance (depends on TIM / thermal pad)
  • RθCS ≈ 0.5–1 °C/W (depending on thermal interface material and mounting quality)
• RθSA: Heat sink-to-ambient resistance
  • RθSA = RθJA − (RθJC+RθCS)
  • RθSA=11.5 − (0.39 + 1)
  • RθSA ​≤9–10 °C/W under your operating conditions (forced convection),
  • choose heat sink based on (RθSA: Heat sink-to-ambient resistance) ​≤ 9–10 °C/W
  • Ensure proper use of thermal interface material and good mounting contact to achieve the expected performance.

All thermal resistances from the chip to ambient (including TIM, heat sink, and mounting interface) must collectively remain within the 11.5 °C/W budget to meet the design requirement. Including this heat sink in your design can help to maintain at an ambient of 60 °C, if ambient is at room temp i.e., at 25 °C then proceed the above calculation with 25°C as ambient.

Thanks,

SudharsanC