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Class D Switching Power Amplifiers and Power D/A conversion

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Old 3rd February 2008, 09:49 AM   #1
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Default Single 300volt rail Class D amplifier?

would it be feasible, to run a class D amplifier off a single 300volt or so rail.

the maths suggests that this would yield about 2500watts of possible output power into 4 ohms, obviously half that into 8 ohms.

is there any class D amplifier IC out there, which could be used to control some high voltage mosfets?

the IC would obviously be run off lower voltage.

National Semiconductor have an IC, except I believe it uses split rails, which wont work in this situation.

thanks for any input.
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Old 3rd February 2008, 03:54 PM   #3
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Why do you need so much power?

Surely 60v rails should provide plenty of power to almost any speaker...
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Old 3rd February 2008, 03:59 PM   #4
luka is offline luka  Slovenia
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Hi

http://www.tripath.com/downloads/RB-TA0105A.pdf

Note that none of them run of single rail, amp would have to be bridge to do that, but when going into bridge more, you have 4 times as much power as you do in single channel, same load.

You are way better off buying one, trust me on this
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Old 3rd February 2008, 06:31 PM   #5
Tim__x is offline Tim__x  Canada
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They already told you in the solidstate forum that this is a bad idea.
Isolation is extremely important.
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Old 3rd February 2008, 07:00 PM   #6
Dave Z is offline Dave Z  United States
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Sooo... you are going to directly rectify the 220v AC wall outlet (I'm assuming you have 220V in Australia and the math works for it) and power an amplifier from it? If you do please make sure the fire department and paramedics are at your house when you turn it on for the first time

Oh... video, don't forget to take video of it. Hire a professional cameraman to video when you turn it on. And make sure he continues to film them as they resuscitate you

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Old 3rd February 2008, 07:33 PM   #7
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Quote:
Originally posted by luka
Hi

http://www.tripath.com/downloads/RB-TA0105A.pdf

Note that none of them run of single rail, amp would have to be bridge to do that, but when going into bridge more, you have 4 times as much power as you do in single channel, same load.

You are way better off buying one, trust me on this
does it HAVE to be bridged?

and who said anything about mains voltage?



an amplifier to give the kinda power I'm looking at may have +-120 - 150 volt rails anyway...

if it can be done with a single rail, it makes things a lot easier.

the aim, is to get about 2500watts rms, into 4 ohms.

this is more an "in theory" thing, than something I'll actually do.
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Old 3rd February 2008, 08:41 PM   #8
luka is offline luka  Slovenia
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hi

if you want single rail yes, if dual/split like +/- then that chip is ok for you...but not for 2.5kw...I am sure you know that, since you won't get that good fets...or if you do...well don't know how it would all work...even higher voltages were used by someone I know, not one but two...
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Old 3rd February 2008, 09:01 PM   #9
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Quote:
Originally posted by ThyDntWntMusic
the aim, is to get about 2500watts rms, into 4 ohms.

this is more an "in theory" thing, than something I'll actually do.
IMO, you would be better off using 5 x 500W RMS amps... Unless you have a single driver that will handle 2000W+...
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Old 4th February 2008, 02:58 AM   #10
Dave Z is offline Dave Z  United States
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OK so now that I know this is just "theory", I would use a single 200V (approx) supply and bridge the output into 8 ohms. You can use one of the high voltage, high and low side gate drive ICs from International Rectifier for each half bridge. Open loop (other than the normal issues associated with open loop) would be OK in this configuration but if you add feedback the high DC voltage from the 50% duty cycle on each half bridge is where you may see some problems. Of course this is theory, in practice you will have tons of issues with layout, parasitics etc with high current and high switching freq. Laugh if you want, but you could even use one of those little 5V 1W-2W filterless class D amps from TI as the modulator and just add the feedback but keep the DC in mind.

Dave
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