Hi There, how are you? 🙂
I am working on a 8-channel car audio amplifier design with 4x TDA8920CTH, please see the attached images.
As per the datasheet, you can observe that the SGND pin was routed to the output part of the design, that being the output filter capacitor, snubber and speaker terminals. The white circle shows the connection between grounds so the current returns in the middle of the board, where there are 4x 2200uF capacitors. However, the design as it is presented has lots of distortion and crosstalk. By deviating the SGND to a "clean" ground in the center of the board, thus ignoring what the datasheet states about routing it to the output componentes, the distortion gets better but not 100%, it can still be heard easily when listening to music in a low volume. It sounds like something is lose and rattling inside the loudspeaker, pretty funny. At louder volumes the distortion is less noticiable, so I believe it is always at the same level regardless of the volume. Notice that all 4 TDAs are in the same ground plane, I am not sure if that is OK or a malpractice. Please advise. I am about to redesign the board to fix this problem, kinda urgent... 😱
Edit: Full res image:
http://imageshack.com/a/img401/8951/tyjk.png
Otherwise the amp is fine, lots of power!
Your input will be highly appreciated!
Thank you!
Best wishes
I am working on a 8-channel car audio amplifier design with 4x TDA8920CTH, please see the attached images.
As per the datasheet, you can observe that the SGND pin was routed to the output part of the design, that being the output filter capacitor, snubber and speaker terminals. The white circle shows the connection between grounds so the current returns in the middle of the board, where there are 4x 2200uF capacitors. However, the design as it is presented has lots of distortion and crosstalk. By deviating the SGND to a "clean" ground in the center of the board, thus ignoring what the datasheet states about routing it to the output componentes, the distortion gets better but not 100%, it can still be heard easily when listening to music in a low volume. It sounds like something is lose and rattling inside the loudspeaker, pretty funny. At louder volumes the distortion is less noticiable, so I believe it is always at the same level regardless of the volume. Notice that all 4 TDAs are in the same ground plane, I am not sure if that is OK or a malpractice. Please advise. I am about to redesign the board to fix this problem, kinda urgent... 😱
Edit: Full res image:
http://imageshack.com/a/img401/8951/tyjk.png
Otherwise the amp is fine, lots of power!
Your input will be highly appreciated!
Thank you!
Best wishes
Attachments
Last edited:
Please see the attached image the output waveform of the carier frequency after the output filter.
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