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zox2003 21st November 2007 02:30 AM

Ir2104+ Irf540
Can I use IR2104 to drive 2 x IRF540 in class D?
How much power should I expect driving output IRF's 540 with +/- 40V and driving it with IR2104 (Vcc=12V for 2104)?


LM311 + IR2104 + 2x IRF540 + Out.filter - Zout=4 ohms


zox2003 21st November 2007 02:48 AM

2 Attachment(s)
Here is picture of my PCB and some components markings on.
PCB is double sided.PArts are on top side and GND is all bottom side.Heatsink will me mounted on bottom side of PCB.I will cut off PCb where IRF540 are and mount them on heatsink.

I still need answers on my previous question.


Eva 21st November 2007 06:15 AM

Judging by the questions about elementary electronics that you make, you don't seem to be ready at all for such a project (and there is already too much low-quality class D out there giving us a bad name :dead: )

The theoretical maximum RMS power output is V^2/(2*R) where V is peak output voltage, that you can assume to be rail voltage (40V for your case). Do the math. For class D you have to ensure that both the MOSFETs and the output inductor can handle the required peak current for the rated impedance (at least 10A for 40V on 4 ohms). Inductor must not saturate.

Concerning the gate driver, have you looked at the datasheet? In top right side of the first page you will find a square filled with big numbers and letters in it. Those numbers and letters are YELLING something like "don't even try this IC for class D", and you should learn to interpret them before continuing the project.

zox2003 21st November 2007 01:11 PM

Why is this IC not usable for class D.It is half a bridge mosfet driver.Explanation????

Eva 21st November 2007 01:28 PM

:headbash: :headbash: :headbash:

Whortless 21st November 2007 01:31 PM

Ok you can do an amplifier but, the problem will be the quality. If I were you would use 2110,2113 perhaps 2011. The IC you would like to use has internal ~500ns deadtime which will cause crossover distorsion like an unproper biased classAB amplifier. Also the IC has long ton/off speeds and has low drive capability. I think an expert "Eva" can give more explanation.
Any way I do not know if are they pin compitable but , try HIP2100/2111(ISL2111/2110) or LM5104/5105 . You should consider your driver selection.

Good luck!

zox2003 21st November 2007 01:50 PM

On one other forum I found schematics using IR2104.I understand what is your point but people claimed that amp is working great.



I am expecting help from you guys.Do not play smart ****s and just place critics like E*a.

Thanks anyway

lumanauw 21st November 2007 02:14 PM

Hi, zox2003,

How about IR2011? This one is the same 8DIP IC.

luka 21st November 2007 03:08 PM


YOu should go for 2110 or 2011. You amp will work, BUT it depends how good you can hear, which in your case must not be good at all... Build it and build one with other chip and you should/will hear the diffrence. Best of luck anyway...

zox2003 21st November 2007 05:05 PM

2 Attachment(s)
Here is a schematic from other site using same IC

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