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Audio Amplifiers Forum
TPA3122D2 Class-D Audio Power
I've built an audio amplifier based on TPA3122D2 and it sound is very good.
I've two questions:
the 10uF capacitor connected to pin 17 and ground (see figure 28 datasheet) i not find a ceramic or polyester, is good a 10uF electrolitic capacitor? (my amplifier sound without it)
My amplifier in configurated in SE with two 8 ohm speaker impedence. I use a 47uH filter inductor and 390 nF filter capacitor (see table 3 datasheet), the DC blocking capacitor is 470uF for 40Hz filter response. (table 2 datasheet)
well my question is: what is the function of the two 4,7K resistor paralleling the my 390 nf capacitor ( 690 nF in the figure 28 for 4 ohm application) and the 4,7K values is good for my 8 ohm application? what is the best value of the two resistors for 8 ohm speakers?
Excuse for my bad english.
That's a nice looking board you have there!
You may want to check out our EVM - both for an example of a good layout, as well as to check our BOM. We show a Murata GRM32DF51H106ZA01L ceramic cap for pin 17, but an electrolytic should be fine as well, as long as you put a 0.1 uF ceramic in parallel with it.
The 4k7 ohm resistors are used to discharge the dc blocking cap when the amp is turned off, either by removing the power supply, or putting it in shutdown. This helps with pop performance, so the absolute value is not critical.
I'm glad that you like our amp! Let us know if you have any other questions!
PS Your English is waaaay better than my Italiano!!!!
Audio Applications Engineering Manager
Dallas, TX USA
thanks for your reply.
I've replaced 10uF electrolitic capacitor, and have a parallel 0.1uF polyester cap. the board work very well and have good sound but your evaluation board is best for me.
I'm unable to solder SMT components.
I understand the function of the two resistors.
thanks thanks again.
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