TAS5756M: Full scale DAC output range

Hi Satoshi-san,

First, we should note that we must make some assumptions:

1. That the gain of the digital path is 0dB or 1FS.
2. That the gain of your amplifier is set to 26dBV.

If those two things are true, then we can say that at 1FS, you will clip a 26.4V supply. This is because the gain structure would attempt to develop a voltage of ≈28.2V (peak) at the ouput of the amplifier. Since the PVDD voltage is only 26.4V, it would become clipped.

For the second use case, you would be even more clipped, since the closed loop amplifier would attempt to drive the outputs to ≈28.2Vpk. In this use case scenario, if you are going to run with a 10V PVDD supply, it would be preferable to run with the gain at 20dBV, since the noise and THD+N performance would be better. You just don't need that much gain if you only have 10V PVDD and have a digital signal which will drive the DAC to 0dB (or higher).

Hope that helps- Diego may jump in with more specifics or let us know if you have any other questions.

Thanks,
Cody

Cody-san, Diego-san

Thank you for reply.
I looking forward specifics update.

Best regards,
Satoshi

Hi, Satoshi,

As Cody mentioned, the closed loop amplifiers have a gain structure configured to have a fixed output. The output of the amplifier with full scale input is set to be 26dBV per volt, so the output expected would be about 19.95Vrms, but to get this output level, a power supply of about 28.2V is required. 

Best Regards,

  -Diego Meléndez López
   Audio Applications Engineer

Diego-san

Thank you for information.
I feel that output is 1.995Vrms, which is correct 19.95Vrms or 1.995Vrms?

Best regards,
Satoshi

Hi, Satoshi,

I was referring to the Speaker output of the TAS5756M. If the value you are looking for is the DAC output, the full scale output voltage is ~2 Vrms by default. 

Best Regards,

  -Diego Meléndez López
   Audio Applications Engineer