This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

LM49352: how to measure input power to speaker unit from Class-D output

Part Number: LM49352

I have few speaker RMA(O/C) and speaker supplier suspect maybe over driving from LM39452.

in this case, how can I confirm the input power to a speaker is less than 1Watt with 4.2VDD

  • WONHO KIM,

    I would recommend making use of the DAC effect monitor registers 0xB8-0xBC This will let you know if there is any internal clipping taking place, or if the ALC is distorting. You definitely make use of theAudio compressor if you want to ensure that the volume is held in check.
    If you are seeing some clipping, you may make use of some of the attenuation provided in the Digital mixer. Typically the clipping would be caused by summing multiple sources.

    If you aren't seeing any clipping there, I would check your DAC_L_LEvel and your DAC_R_Level. you may simply need to turn the digital gain down.

    between the digital gain and DAC compressor, you should be able to keep the clipping in check. The Class-D amp is spec'd at 970mW with LSVDD =4.2V.

    best regards,
    -Steve Wilson
  • thank you, Steve

    but, I could not find any details of 0xB8h?

    how do I know whether this is clipped or not? there is no range or explanation from datasheet?

  • Wonho Kim,

    below is a diagram from the datasheet.  Register 0xBA will show if the SoftClip block, EQ or Gain blocks are clipped. obviously you don't want clipping in any block,  and its possible to clip one block, but not clip the DAC,  

    I will need to look into the documentation for more information about 0XB8 and get back to you.

    best regards, 

    -Steve wilson