Using LM4651 as basis for PWM amplifier

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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.
 
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?
 
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