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LM4780 (LM3886) impedance issues
LM4780 (LM3886) impedance issues
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Old 21st November 2006, 11:33 AM   #1
Alfetta87 is offline Alfetta87  France
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LM4780 (LM3886) impedance issues
Default LM4780 (LM3886) impedance issues

The national semiconductor datasheet doesn't say if the bridged (or parallel) application of the LM4780 would hold on with a 4 ohms load, even with its maixmum voltage used.

Has anybody got some experience with that?

Same for the LM3886 in brdiged mode.


- dan
It's better to keep your mouth shut and appear stupid than open it and remove all doubt...
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Old 21st November 2006, 02:35 PM   #2
jackinnj is online now jackinnj  United States
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LM4780 (LM3886) impedance issues
If you look at the "overture design tool" on National's website you can quickly determine the heat sink rating for a given rail voltage and impedance.

You can play around with the numbers and determine which heat sink/rail voltage combination is appropriate -- there's no need to guess.

I have used the LM4780 at higher PDMax than recommended by National by using forced air through the heat sink -- be mindful this causes the thermal protection to cycle on-and-off -- it's a nice experiment but something that you shouldn't try at home on your expensive speakers.
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