Hello everyone,
I'm in the middle of making an audio hat for my Pi and I'm looking to see if anyone has worked with these TPA2008D2 chips before. It seemed like a nice and simple class D amp to run on 5V that didn't need much power or many extra components. I also wanted something that I could connect a set of 8Ω speakers or my headphones to.
I bread-boarded the reference circuit (outlined in the TPA2008D2EVM_UG.pdf document of the eval board) with the following modifications:
- RIN(-) and LIN(-) tied to GND.
- Volume R3 pot added 18KΩ between pot and VDD (keep the volume between 0 and 3.7V vs 0 and 5V).
- ROUT(+) and LOUT(+) each have a 470uF 50v electrolytic cap before going to a headphone jack.
I'm having issues where when I raise the volume to between 80-90% I hear static (not like amplified background noise but like the chip is generating white noise) and above 90% it goes away. I've been testing this circuit by itself on a 5V bench supply with with and without my DAC tied to RIN(+) and LIN(+).
I have tried letting RIN(-) and LIN(-) float with no change. Also I tested connecting the headphone jack common to LOUT(-) instead of GND.
I've not looked further into it yet, but I do see quite a bit of ringing on the output square wave at the transitions.
I'm still very novice with analog circuits (I'm a software guy who is still learning), so any help would be appreciated.
Thank you! -Peter
I'm in the middle of making an audio hat for my Pi and I'm looking to see if anyone has worked with these TPA2008D2 chips before. It seemed like a nice and simple class D amp to run on 5V that didn't need much power or many extra components. I also wanted something that I could connect a set of 8Ω speakers or my headphones to.
I bread-boarded the reference circuit (outlined in the TPA2008D2EVM_UG.pdf document of the eval board) with the following modifications:
- RIN(-) and LIN(-) tied to GND.
- Volume R3 pot added 18KΩ between pot and VDD (keep the volume between 0 and 3.7V vs 0 and 5V).
- ROUT(+) and LOUT(+) each have a 470uF 50v electrolytic cap before going to a headphone jack.
I'm having issues where when I raise the volume to between 80-90% I hear static (not like amplified background noise but like the chip is generating white noise) and above 90% it goes away. I've been testing this circuit by itself on a 5V bench supply with with and without my DAC tied to RIN(+) and LIN(+).
I have tried letting RIN(-) and LIN(-) float with no change. Also I tested connecting the headphone jack common to LOUT(-) instead of GND.
I've not looked further into it yet, but I do see quite a bit of ringing on the output square wave at the transitions.
I'm still very novice with analog circuits (I'm a software guy who is still learning), so any help would be appreciated.
Thank you! -Peter