full bridge selfosc class d amp

Tekko · 28th October 2007, 01:14 PM

Heres yet another new idea i have this is for a subwoofer amp.

schematic

What do you think ? Suggestions for improvements are welcome.

Eva · 28th October 2007, 01:20 PM

This is not self oscillating.

Tekko · 28th October 2007, 01:42 PM

hum i don´t see a carrier generator around

Eva · 28th October 2007, 02:47 PM

Ok, I give up...

Pabo · 28th October 2007, 03:33 PM

Eva

"Ok, I give up..."

That was funny

Tekko

Your IC2 will probably have enough phase lag to cause self oscillation but it will be grossly non linear as it will be working in slew limiting mode all the time. I suggest that you add poles to IC2 and choose a model with high bandwidth for example AD8512.

I do not think that the driver will work well with one input low all the time? How where you thinking there?

Instead put a comparator after the OPAMP with dual outputs (one inverting).

You also need dual supplies for the OPAMPs (+/-12V).

Tekko · 28th October 2007, 03:52 PM

The input on a HIP4080 actually is a comparator.

I have seen schemes with poles on th feedback, add second set of resistors and place caps to ground, but i´m not sure if theres any benefit or any difference in doing that.

There is also LT1220, but all i have available at this time is TL082 and LF356.

Tekko · 28th October 2007, 04:11 PM

So heres one with dual output comparator before HIP4080:

schemo

I can´t find the AD suggested in eagle.

Tekko · 29th October 2007, 01:23 PM

I´m not trying out this thing on a breadboard.

I´ll let you know how it goes.

Tekko · 29th October 2007, 08:33 PM

It dident work, the HIP4080 get hotter than hell.

Whortless · 30th October 2007, 10:49 AM

Tekko,

Put a reference on + input of the 4080 (12V/2=6V). So you do not need symetrical opamp supply( do not left +in of the comparator floating). Pay attention to voltage on Vdd/Vcc pin of 4080, it should not exceed 15V. TL082/072 can work here but AD8512 is better.

Regards

28th October 2007, 01:14 PM	#1
Tekko diyAudio Member Join Date: Jan 2005	full bridge selfosc class d amp Heres yet another new idea i have this is for a subwoofer amp. schematic What do you think ? Suggestions for improvements are welcome.

28th October 2007, 01:20 PM	#2
Eva diyAudio Member Join Date: Oct 2003 Location: Near the sea	This is not self oscillating. __________________ I use to feel like the small child in The Emperor's New Clothes tale

28th October 2007, 02:47 PM	#4
Eva diyAudio Member Join Date: Oct 2003 Location: Near the sea	Ok, I give up... __________________ I use to feel like the small child in The Emperor's New Clothes tale

28th October 2007, 03:33 PM	#5
Pabo diyAudio Member Join Date: Feb 2003 Location: Helsingborg, southern sweden	Eva "Ok, I give up..." That was funny Tekko Your IC2 will probably have enough phase lag to cause self oscillation but it will be grossly non linear as it will be working in slew limiting mode all the time. I suggest that you add poles to IC2 and choose a model with high bandwidth for example AD8512. I do not think that the driver will work well with one input low all the time? How where you thinking there? Instead put a comparator after the OPAMP with dual outputs (one inverting). You also need dual supplies for the OPAMPs (+/-12V). __________________ If something that measures good doesn´t sound good, measure again!

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28th October 2007, 01:42 PM	#3
Tekko diyAudio Member Join Date: Jan 2005	hum i don´t see a carrier generator around

28th October 2007, 03:52 PM	#6
Tekko diyAudio Member Join Date: Jan 2005	The input on a HIP4080 actually is a comparator. I have seen schemes with poles on th feedback, add second set of resistors and place caps to ground, but i´m not sure if theres any benefit or any difference in doing that. There is also LT1220, but all i have available at this time is TL082 and LF356.

28th October 2007, 04:11 PM	#7
Tekko diyAudio Member Join Date: Jan 2005	So heres one with dual output comparator before HIP4080: schemo I can´t find the AD suggested in eagle.

29th October 2007, 01:23 PM	#8
Tekko diyAudio Member Join Date: Jan 2005	I´m not trying out this thing on a breadboard. I´ll let you know how it goes.

29th October 2007, 08:33 PM	#9
Tekko diyAudio Member Join Date: Jan 2005	It dident work, the HIP4080 get hotter than hell.

30th October 2007, 10:49 AM	#10
Whortless diyAudio Member Join Date: Nov 2005 Location: Kocaeli,Turkey	Tekko, Put a reference on + input of the 4080 (12V/2=6V). So you do not need symetrical opamp supply( do not left +in of the comparator floating). Pay attention to voltage on Vdd/Vcc pin of 4080, it should not exceed 15V. TL082/072 can work here but AD8512 is better. Regards

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