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Original question:

TAD5242EVM-K: Only one Output with a flat line at 0 when using the math function in the oscilloscope.

TAD5242EVM-K: no output after connecting it to an audio amplifier

Ena Peh
Prodigy 210 points
Part Number: TAD5242EVM-K
Other Parts Discussed in Thread: LM48560, TAD5242

Tool/software:

Hi Experts!

I am currently evaluating the TAD5242 eval board and I connected the output to the LM48560 eval board. Initially it worked just fine and I was able to see a sine wave with my desired output based on the gain I set on the audio amplifier. However, after a while, there is no output signal on the amplifier side. I measured the signal on the TAD5242 test points as well and no signal comes out from the TAD5242 side. Is there any other way I can configure this and make sure that it works for i2s target stereo mode?

Best 

Ena

  • 0
    TI__Mastermind 30671 points

    Hello Ena,

    If it worked fine at first it seems your configuration, data format and clks were fine. You can read some of the flags to see if any flag can give you any indications.

    To debug I would remove the amplifier first and retry to make sure the output stays fine without the amplifier. If so, then the loading might be the issue.

    Note that the Headphone Load Range is 8 to 300 Ohm and Line-out Load Range is >600 Ohm  . Headphone/Line-out Cap Load  range is 0 to 550 pF. With input impedance of the LM device be 46K to 58k , so Line-out connection to LM48560 should be ok.

    Kind Regards,

    Arash

  • 0 in reply to Arash Loloee
    Prodigy 210 points

    HI Arash,

    I removed the amplifier and there is no more outputs from the TAD5242 anymore when I was trying to debug

    Best

    Ena

  • +1 in reply to Ena Peh
    TI__Mastermind 30671 points

    You have to go through step by step debug:

    1-Make sure all the jumpers are intact and as it was before ( refer to users guide for detail of each configuration

    2-Monitor ALL supply voltages.

    3- Plot I2S signal on the SAME window and make sure it is similar to Figure 6-5. or 6-6 ( if your configuration is for I2S)

    Basically you have to make sure configuration ( jumper) , supplies  and clk/input is correct . Once they all correct, it shoule work as it is HW control and there is no register to configure for this one.

    Regards,

    Arash