For my circuit, I have mounted heatsinks to my mosfets to dissipate heat. I have below a crude drawing of how the heatsink/mosfet is placed on the PCB
I was thinking to integrate a LM35 to measure temperature, and to turn on a fan when the heat of the mosfet/heatsink gets too high, so that the air may cool down the mosfet/heatsink.
My question is, can I place a fan in some way that would cool off the mosfet/heatsink? If so, how? I was thinking to place the fan on top to suck air from the heatsink and blow the heat upwards?
Would this work? I don't think placing the fan to blow at the mosfet/heatsink would work since the heat would just dissipate into the board?
Would my mosfet/heatsink placement even allow for an effective fan to be placed?
UPDATE: So my design for placing the fan above the heatsink should work from what I'm gathering. Though I am still unsure of where I should direct airflow.
@Swonkie: If I enclosed the bottom of my fan into a shroud like WhatRoughBeast suggested, would the airflow be "directed"? If I implemented a shroud, would the air be drawn directly from the mosfet/heatsink strictly? If I did direct airflow to the mosfet/heatsink, wouldn't the heat dissipate through to my PCB board?
ALSO: As I am using an LM35 for temperature sensing, should I place the LM35 so that it's touching the heatsink or the mosfet itself? Which would be more effective implementation for temperature reading?