I need help in designing a heatsink for my PCB

Discussion in 'The Projects Forum' started by pjreijiri, Apr 22, 2016.

  1. pjreijiri

    Thread Starter Member

    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?
  2. Picbuster


    Dec 2, 2013
    pjreijiri likes this.
  3. SLK001

    Well-Known Member

    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.
    pjreijiri likes this.
  4. shortbus

    AAC Fanatic!

    Sep 30, 2009
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