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Class-D audio amplifier exhibits power density of 3.2-W/mm-square

1/25/2012 01:56 AM EST
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re: Class-D audio amplifier exhibits power density of 3.2-W/mm-square
Rick_Hille   1/25/2012 5:05:10 PM
The datasheet offers little insight into the Smart Protection. Maybe I'm missing something but when I read the description, it sounds like the device immediately clamps the current to some unspecified peak value (first threshold) and has the ability to distinguish a dead short (second threshold). The typical way that can be done is by measuring the voltage that develops across the load during the clamping condition, and if its below a certain level, declare a shorted condition. While this is all happening, of course, a horrible distortion is introduced due to the first threshold clamping. There is nothing in the information ST posted for the device that reveals the mechanism described in the article, which has a time element to it when they speak of specific frequency range. If it is time based, such as SOA protection (see National Semi's SPIKE mechanism), it would be reasonable to expect that the thresholds are "time at level" determinations. This approach would hold off limiting the occasional large audio peak and only react to a sustained series of high current peaks that would threaten the SOA limit.

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re: Class-D audio amplifier exhibits power density of 3.2-W/mm-square
agk   1/25/2012 1:14:06 PM
The smart current protection embedded into this chip seems to produce clean sound while a music contains large changes in its sound levels at certain frequency ranges.This will reduce inter harmonic distortion and automatically prevents any interruptions in the sound flow.

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