Fan selection

Electronics4you

Member

• Feb 13, 2007

• #1

Hi there,

I have a circuit with four power MOSFETs. Near them (or on the heat sink) is placed a temperature sensor, which detects when the temperature is above a certain level. Now for the tricky bit...

How do a select the right fan/heat sink for the application?

I know the effect of the MOSFETs
I want to calculate the fan flow which is needed to cool down the MOSFETs faster than they heat up, so they don't cook.

 

R

Russlk

New Member

• Feb 13, 2007

• #2

Unless you have applicable data on the heat sink, you will have to experiment.

 

Electronics4you

Member

• Feb 13, 2007

• #3

Do I need total area, thermal resistance, material...?

 

R

Russlk

New Member

• Feb 13, 2007

• #4

Do I need total area, thermal resistance, material...?
No, you just have to make measurments and collect data.

 

audioguru

Well-Known Member

Most Helpful Member

• Feb 13, 2007

• #5

You just need the datasheet info for the heatsink, unless you made the heatsink by accident. You also need the datasheet info for the Mosfets.

 

K

kchriste

New Member

Forum Supporter

• Feb 13, 2007

• #6

Do I need total area, thermal resistance, material...?

Click to expand...

Yes, and how much power will be dissipated by the MOSFETs (worst case), the max junction temp for the MOSFETs, any airflow restriction and what the working ambient temperature range will be. It can be pretty complicated and it is usually easier to determine this experimentally.

 

Electronics4you

Member

• Feb 14, 2007

• #7

Yes I know I need all that datasheets, but how do I calculate it?
I have no idea
Have you any examples?

 

K

kchriste

New Member

Forum Supporter

• Feb 14, 2007

• #8

A quick Google of "heatsink design" turned up this:
**broken link removed**
And this:
http://www.flomerics.com/flotherm/technical_papers/t226.pdf

 

Last edited: Feb 14, 2007