IRS2092 Amp Design Review - Page 2

Workhorse · 10th February 2010, 07:25 AM

Quote:

Originally Posted by brent113

I have read all of the related application notes. Care to make any suggestions for improvements? I do not have a fundamental understanding of RF and switching electronics as they are not currently in my major. I will be studying those in years to come.

Minimise gate/source trace length
Minimise the switching node area between mosfets also
and a solid grounplane is a must

besides this there are many key factors which fall under basic switching electronics fundamentals. I am surprised how you took class-d as your project without knowing these.

theAnonymous1 · 10th February 2010, 07:55 AM

Give the guy a break; the world with not implode in on itself if his project fails.

If you think he doesn't deserve your input, then don't give any input.

Workhorse · 10th February 2010, 09:46 AM

Quote:

Originally Posted by theAnonymous1

Give the guy a break; the world with not implode in on itself if his project fails.

If you think he doesn't deserve your input, then don't give any input.

Ok lets waste money

brent113 · 10th February 2010, 02:50 PM

Thanks for the feedback. It's brutal, but I knew it was coming :P

Quote:

Originally Posted by Workhorse

Minimise the switching node area between mosfets also

One problem I was having with the layout of the FETs was since I was using single TO-220 heatsinks I valued not overlapping the footprints of those. If I had access to a solid custom drilled heatsink I probably could have done a lot better. Was there a way I missed that I could move the FETs closer together without screwing up the cooling?

Quote:

Originally Posted by Workhorse

and a solid grounplane is a must

Is trying to do this on a 2-layer board pointless? I've heard "use a 4 layer board" before but that wasn't an option. Or, did I just lay it out that poorly and could have gotten away with 2 layers but didn't.

Quote:

Originally Posted by Workhorse

I am surprised how you took class-d as your project without knowing these.

I'm ambitious? :P This subject really interests me, and I figured I'd go for it. Go big or go home, right? Unfortunately, I've been studying computer networks and IC design, not power electronics, so I've missed a lot of the RF subject matter.

Workhorse · 10th February 2010, 03:06 PM

Quote:

Originally Posted by brent113

Thanks for the feedback. It's brutal, but I knew it was coming :P

One problem I was having with the layout of the FETs was since I was using single TO-220 heatsinks I valued not overlapping the footprints of those. If I had access to a solid custom drilled heatsink I probably could have done a lot better. Was there a way I missed that I could move the FETs closer together without screwing up the cooling?

Is trying to do this on a 2-layer board pointless? I've heard "use a 4 layer board" before but that wasn't an option. Or, did I just lay it out that poorly and could have gotten away with 2 layers but didn't.

I'm ambitious? :P This subject really interests me, and I figured I'd go for it. Go big or go home, right? Unfortunately, I've been studying computer networks and IC design, not power electronics, so I've missed a lot of the RF subject matter.

At least read IR app notes on class-d amps on www.irf.com under audio section, you will learn a great deal as a beginner.

brent113 · 10th February 2010, 03:28 PM

I have read those, and specifically in AN-1135 a star ground is recommended instead of a ground plane. Most reference designs I've seen though use a ground plane.

I guess a couple revisions I would make now are make the bottom middle plane at -B and the top at +B instead of both at the same reference and break up the ground plane a bit around the input circuitry.

Not sure how I could move the FETs in and shorten the gate traces without finding a better heatsink solution. Getting the FETs in D-FET packaging would've allowed me to shorten the traces to within an inch but I don't have any sinks for those. That was my logic at least, not trying to defend it.

Workhorse · 10th February 2010, 03:36 PM

Go and see reference designs on IR website IRDAMP, there are TO-220 mosfets relatively mounted closely to gate driver, if you care to do that.

brent113 · 10th February 2010, 03:40 PM

Those designs have a solid alum. block heatsink if you are referring to iraudamp7. Is there another ref that I missed? Thought audamp5 and 7 were the only ones they have posted.

Workhorse · 10th February 2010, 04:34 PM

http://www.irf.com/technical-info/re.../iraudamp1.pdf

brent113 · 10th February 2010, 04:35 PM

Yea, that has the same custom drilled heatsink.

10th February 2010, 07:55 AM	#12
theAnonymous1 diyAudio Member Join Date: Feb 2004 Location: Anonymityville	Give the guy a break; the world with not implode in on itself if his project fails. If you think he doesn't deserve your input, then don't give any input. __________________ "If you don't like funerals don't kick sand in Ninja's face." - Ninja

10th February 2010, 03:36 PM	#17
Workhorse diyAudio Member Join Date: Dec 2004	Go and see reference designs on IR website IRDAMP, there are TO-220 mosfets relatively mounted closely to gate driver, if you care to do that. __________________ It's a fruitless endeavor to try and educate a fool that rejoices in ignorance

10th February 2010, 04:34 PM	#19
Workhorse diyAudio Member Join Date: Dec 2004	http://www.irf.com/technical-info/re.../iraudamp1.pdf __________________ It's a fruitless endeavor to try and educate a fool that rejoices in ignorance

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10th February 2010, 03:28 PM	#16
brent113 diyAudio Member Join Date: Dec 2009 Location: Oregon	I have read those, and specifically in AN-1135 a star ground is recommended instead of a ground plane. Most reference designs I've seen though use a ground plane. I guess a couple revisions I would make now are make the bottom middle plane at -B and the top at +B instead of both at the same reference and break up the ground plane a bit around the input circuitry. Not sure how I could move the FETs in and shorten the gate traces without finding a better heatsink solution. Getting the FETs in D-FET packaging would've allowed me to shorten the traces to within an inch but I don't have any sinks for those. That was my logic at least, not trying to defend it.

10th February 2010, 03:40 PM	#18
brent113 diyAudio Member Join Date: Dec 2009 Location: Oregon	Those designs have a solid alum. block heatsink if you are referring to iraudamp7. Is there another ref that I missed? Thought audamp5 and 7 were the only ones they have posted.

10th February 2010, 04:35 PM	#20
brent113 diyAudio Member Join Date: Dec 2009 Location: Oregon	Yea, that has the same custom drilled heatsink.

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