I am following this video from EEV blog where he talks about calculating heatsinks and I noticed that he does not talk about multiple components sharing a single heatsink. I have lurked around the web but I have not been able to figure out how it is done.

This is the thermal circuit for a single transistor in a single heatsink as shown in the video enter image description here

How would the thermal circuit for two or three transistors mounted in the same heatsink look like?


Something like this:

If there are multiple pads, then the branch would happen after the pads and there would be three pad resistors under the transistor thermal conductances.


simulate this circuit – Schematic created using CircuitLab

  • \$\begingroup\$ Great!, so if I solve this circuit I can calculate the heatsink I need to get the transistors at a certain temperature, right?. thanks! \$\endgroup\$ – Joaquin Brandan Mar 3 at 20:43
  • \$\begingroup\$ Yep, as a reality check, you could compare it to the case of one transistor with 3x time heat, this result should be a lower temperature \$\endgroup\$ – Voltage Spike Mar 3 at 20:56
  • 1
    \$\begingroup\$ Actually now that I think about it, the pads should be branched... \$\endgroup\$ – Voltage Spike Mar 3 at 20:57

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.