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IC Audio Power Amplifiers and Zobel Networks: One Size Does Not Fit All

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PeterLob
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re: IC Audio Power Amplifiers and Zobel Networks: One Size Does Not Fit All
PeterLob   5/21/2008 5:00:00 PM
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Very well-written article

FlySR22
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re: IC Audio Power Amplifiers and Zobel Networks: One Size Does Not Fit All
FlySR22   5/15/2008 3:32:49 PM
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Yes, since the Zobel network is in parallel with the speaker, the resistor wattage will have to be considered, depending on the operational requirements of the system. Adding diodes to the output adds more expense, since the Zobel network is still usually required. Both the low-side and high-side drivers need diodes since parasitics can turn ON if the voltage at the output exceeds the supply voltage by 600 mV. Normal silicon diodes cannot be used since they are biased ON at the same voltage as the parasitics and would not prevent the parasitic from turning ON. Schottky diodes (more expensive) with their lower forward voltage would have to be used.

Trinity51
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re: IC Audio Power Amplifiers and Zobel Networks: One Size Does Not Fit All
Trinity51   5/15/2008 11:30:54 AM
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A nice article - thanks! I should point out that any 20kHz power testing using say 8R and 2 uF across the output will fry the 8R resistor instantly unless it is a very large component. Might one potentially solve this problem with a (normally) reverse biased diode connected between the LS output and the negative rail? When the output swings about 0.6V below the negative rail this conducts and thus prevents the 1V or more excursions shown in the experiment.

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