I need help in designing a heatsink for my PCB

Thread Starter


Joined Aug 19, 2015
Hello everyone,

I am designing a controller for 2 hub motors and I am using IRFP4468 MOSFETs.
There are 8 MOSFETS in total but only 4 working at any time since I am using them as H-Bridges.
I am new in the world of PCBs. I already finished the PCB design but I need to design a heatsink for it.
I tried calculating the heat load, I got the following
I=7.5 A through each H-bridge
V=48 V
q=123.6 W
Osa=0.3 C/W

Did I do the calculations correctly?

Now I need to figure out if I need a heatsink and if yes, how big do I need it to be?


Joined Nov 29, 2011
The RDS(on) for this device full on is only 2.6mΩ. The power dissipated by the device will be P=I^2⋅R. At 7.5A, P will be 0.146 watts. Your device is rated for over 250 AMPS drain current.

IF this device is operated at either FULL-ON or FULL-OFF, then any basic heatsink can be used, since it will only dissipate 0.073 watts operating at 50% duty cycle. You might be able to even dispense with the heatsinks, depending on the duty cycle.