Using LM4651 as basis for PWM amplifier

fr0st · 25th May 2003, 11:03 AM

Alot of threads have been looking for a Class D amp fo large output powers and alot of thread have people reccommending the lm4651/52 as the solution.
My idea is to use it as the controller and along with mosfet high side drivers (or equivalant) and seperate the IC and h-bridge voltage (the h-bridge obviously higher than the +-22v national states) so that a larger output power can be obtained. First of all the lm4652 would need to be eliminated and replaced with a high power mosfet stage.
One problem is by eliminating the lm4652 most of the protection is gone and if you have the h-bridge on a seperate voltage to the controller it would require the feedback being modified.
I'd be willing to try and make the contraption but I don't have all the knowlage to design it.

I'd be hoping for something like a design for a diy car audio solution for large low inpedence loads (500+w RMS).

Has anyone though about or attemped a similar thing?
A kick in the right direction would be greatly appreciated.

Circlotron · 26th May 2003, 03:11 AM

Here's something I did recently, might be of interest to you.
http://diyaudio.com/forums/showthrea...136#post172136

fr0st · 26th May 2003, 07:55 AM

The BCA whitepaper is interesting but probly wouldn't work well with the lm4651 due to its h-bridge.
I found some logic level 60v 75 amp fets that should work well with the lm4651. According to its FAQ the gate voltage is 6v higher than the source which is plenty for the fets (fully on @ 5v).
National says the max for both devices is +-22v, on its own would the lm4652 go alot higher with a regulated supply?

mgm2000ro · 22nd December 2005, 11:01 AM

Hello,everybody!
Like idea of mr "fr0st"

Please,help me to build corectlly this diagram!
I wait any idea!

25th May 2003, 11:03 AM	#1
fr0st diyAudio Member Join Date: Dec 2002 Location: Australia	Using LM4651 as basis for PWM amplifier Alot of threads have been looking for a Class D amp fo large output powers and alot of thread have people reccommending the lm4651/52 as the solution. My idea is to use it as the controller and along with mosfet high side drivers (or equivalant) and seperate the IC and h-bridge voltage (the h-bridge obviously higher than the +-22v national states) so that a larger output power can be obtained. First of all the lm4652 would need to be eliminated and replaced with a high power mosfet stage. One problem is by eliminating the lm4652 most of the protection is gone and if you have the h-bridge on a seperate voltage to the controller it would require the feedback being modified. I'd be willing to try and make the contraption but I don't have all the knowlage to design it. I'd be hoping for something like a design for a diy car audio solution for large low inpedence loads (500+w RMS). Has anyone though about or attemped a similar thing? A kick in the right direction would be greatly appreciated.

26th May 2003, 03:11 AM	#2
Circlotron diyAudio Member Join Date: Jun 2002 Location: Melbourne, Australia	Here's something I did recently, might be of interest to you. http://diyaudio.com/forums/showthrea...136#post172136 __________________ Best-ever T/S parameter spreadsheet. http://www.diyaudio.com/forums/multi...tml#post353269

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26th May 2003, 07:55 AM	#3
fr0st diyAudio Member Join Date: Dec 2002 Location: Australia	The BCA whitepaper is interesting but probly wouldn't work well with the lm4651 due to its h-bridge. I found some logic level 60v 75 amp fets that should work well with the lm4651. According to its FAQ the gate voltage is 6v higher than the source which is plenty for the fets (fully on @ 5v). National says the max for both devices is +-22v, on its own would the lm4652 go alot higher with a regulated supply?

22nd December 2005, 11:01 AM	#4
mgm2000ro diyAudio Member Join Date: Nov 2004 Location: Bucharest	Hello,everybody! Like idea of mr "fr0st" Please,help me to build corectlly this diagram! I wait any idea!