0
\$\begingroup\$

I am trying to make a design that makes use of the TDA7265 to amplify sound. I have already had several iterations where I redesigned and ordered a PCB to test out the design, but each seemed to have its own issues. I once got the TDA7265 to work, but only when the sound input wasn't tied to ground, but to some pin on the TDA7265 following some schematic I found somewhere. The problem with that design was that I wanted to have two possible sound sources, sound from an Arduino Due on the same PCB as the sound amplifier (sharing same power source) AND sound from an audio jack input. I have in mind for the audio jack to provide sound like music for most of the time and for the Arduino Due to sometimes produce status messages like "warning, low power."

For this, I made the design seen in the attached schematic, but there is NO sound regardless of the sound source. I have also verified that the Arduino Due produces sound on DAC0 pin. At most you hear some clicking sounds from time to time. The MUTE pin is measured to be 4V. VIN+ is 12V and I have also made sure that the "PLAY" pin is HIGH.

I based my schematic on page 7 of https://pdf1.alldatasheet.com/datasheet-pdf/view/25084/STMICROELECTRONICS/TDA7265.html so I assume it should at least work when no audio jack is connected (as that would just mean a single sound source.) It won't work unfortunately.

Any idea that can point me in the right direction? I don't have much to any experience with sound amplifiers.

Old schematic from before changes suggested in comments: https://i.sstatic.net/tTny1.png

Current schematic:

Updated schematic

\$\endgroup\$
10
  • 1
    \$\begingroup\$ How did you test it? What power supply rails did you use? What was your input source? \$\endgroup\$
    – Andy aka
    Commented Aug 29, 2021 at 9:37
  • \$\begingroup\$ - I verified that there was sound on DAC0 by connecting GND and DAC0 to my PC speakers input audio jack, sound came from the speakers. - The power supply is the AC adapter cui inc smi36-12 (12V 3A), I have verified with a power measurement tool that VIN+ to GND is exactly 12V too. \$\endgroup\$
    – patr0805
    Commented Aug 29, 2021 at 9:55
  • 2
    \$\begingroup\$ I don't know what would be a correct answer for such an open-ended question. But at least you can't just add audio sources together with diodes, and without AC coupling them from each other. \$\endgroup\$
    – Justme
    Commented Aug 29, 2021 at 10:00
  • 1
    \$\begingroup\$ C34 is backwards. Try drawing a more sensible schematic. I find it hard to make much sense of. Build the quality in. \$\endgroup\$
    – Kartman
    Commented Aug 29, 2021 at 10:10
  • 2
    \$\begingroup\$ Do note if the inputs are just wired wrong, the input might never see any audio to amplify. The diodes most likely prevent the circuit from working. Please disconnect the diodes and then try if the audio fed from the audio input connector works properly. \$\endgroup\$
    – Justme
    Commented Aug 29, 2021 at 10:17

1 Answer 1

Reset to default
1
\$\begingroup\$

You're using a unipolar 12V power supply. That means you must use the device in single supply mode. The datasheet you are referencing is from 1998. There is a newer datasheet https://www.st.com/en/audio-ics/tda7265.html from 2002 showing how to connect the part in single supply mode (Figure 2). The basic issue is that you don't have a power supply connection (negative voltage or GND) to the VS- pins of the device. Please modify your circuit to conform to the single supply arrangement shown in figure 2 which will connect VS- to GND. There are a couple of other important components shown in Figure 2 which are required (D1, C2).

As a general guideline, always try to use the datsheet on the device manufacturer's website to ensure you have the most up-to-date information.

\$\endgroup\$

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.