Quote:
Originally Posted by harlequin2
All this to shift the heat dissipation from a resistor to a transistor.
|
Not "ONLY" for that.
But to raise the dissipating current in a quite cheap way.
As you also had written some posts before, if you want to dissipate with 5A, then you need a large and expensive high power resistor. And it's very difficult to remove the heat that gets generated there.
If you use a resistor with metal housing, that will be even much more expensive, and that's a pain to assembly onto a heatsink.
If you use a "cheap" FET, then the heatsink is easy to attach. If you monitor the temp. of the FET, and you play with the PWM of the FET (and the current through on that), then the FET lives long, and dissipates much more current, then the resistor.