Comments on: Power dissipation calculations in MOSFETs https://www.iagent.no/2015/07/07/power-dissipation-calculations-in-mosfets/ High end 3D printer electronics Mon, 24 Oct 2016 10:05:10 +0000 hourly 1 https://wordpress.org/?v=6.9.4 By: Farrukh Zia https://www.iagent.no/2015/07/07/power-dissipation-calculations-in-mosfets/#comment-86887 Mon, 24 Oct 2016 10:05:10 +0000 http://www.thing-printer.com/?p=809#comment-86887 If i want to make an RF amplifier of 1KW, Power Mosfet of what rating should be chosen for this purpose ? futher given i have to use a power supply of 300VDC. What is the difference between power dissipation and power handling of a MOSFET ?

]]> By: Swaroop https://www.iagent.no/2015/07/07/power-dissipation-calculations-in-mosfets/#comment-81573 Fri, 06 Nov 2015 06:26:57 +0000 http://www.thing-printer.com/?p=809#comment-81573 Sir,
For Vgs = 12V, you have written R(ds on)= 3m Ohm
and for Vgs = 5V, you have written R(ds on)= 4m Ohm,
can you please elaborate on how you computed the values of R(ds on) for different Vgs,
Is there a equation relating the two. I have come across only this equation:

R(ds on) = Vds/Id when Vgs=constant,

how to obtain R(ds on) values for different Vgs values?

Thanks

]]> By: Bent https://www.iagent.no/2015/07/07/power-dissipation-calculations-in-mosfets/#comment-73719 Wed, 15 Jul 2015 08:02:42 +0000 http://www.thing-printer.com/?p=809#comment-73719 In reply to Elias Bakken.

Then I must say, those are excellent results. 😀

]]> By: Elias Bakken https://www.iagent.no/2015/07/07/power-dissipation-calculations-in-mosfets/#comment-73265 Wed, 08 Jul 2015 11:18:45 +0000 http://www.thing-printer.com/?p=809#comment-73265 In reply to Bent.

1) I’ve not tried reducing the series resistance on the A4A revision with the gate driver, but that would be interesting in order to verify the theory. I’ll see if I cannot get that done!
2) I used 40 W heater elements from China: http://www.aliexpress.com/item/Single-end-cartridge-heater-dia-6-x-L20mm-12V-40W-140cm-lead-cable-mini-cartridge-heater/738354287.html They are wire wound, so they are probably pretty inductive.
3) Yes, you are a bad guesser. This setup is totally realistic 🙂

]]> By: Bent https://www.iagent.no/2015/07/07/power-dissipation-calculations-in-mosfets/#comment-73199 Tue, 07 Jul 2015 13:33:27 +0000 http://www.thing-printer.com/?p=809#comment-73199 A few questions in random order. 🙂

Did you try, for curiosity’s sake, to just reduce the series resistor?
As you say, it would likely alleviate the problem, but it would be interesting to explore the difference in this application, with or without a gate driver, on equal terms.

What kind of load did you use for the measurements?
I’m guessing it is a purely resistive load, but how would the two circuits compare with the heaters as load? (with a more suitable series resistor, of course)
Of course, I may be a bad guesser..

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