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TPA3116D2: Audio is cutting off every few seconds

Sudarshan K
Prodigy 20 points
Part Number: TPA3116D2

Hi,

I have a serious problem of audio cutting out (not wave chopping , o/p turns off completely) every few minutes or sometimes seconds and the resumes . I have the o/p connected to a 100V LMT (Line matching Transformer) as the speakers used in the application have an LMT too and need a 0-100V audio i/p.

The circuit used is shown - very similar to the one in the datasheet. I have had to bypass the o/p filter as well as using heats up the device significantly. 

The problem seems similar to the one reported on the diyaudio link below but it only happens at high volume (not low volume as reported in the link below. The effect is similar to that seen here -https://www.youtube.com/watch?v=fCSD2zig2lw

https://www.diyaudio.com/community/threads/tpa3116-2-1-channel-bt-sound-cutting-every-1s-low-input-video.327198/

Any help on this problem will be appreciated. 

  • 0
    TI__Mastermind 48740 points

    Hi 

      Could you please let me know what is the PVCC voltage you are using, also the output power and load resistance? It is possible the over voltage fault is keep triggering, and this fault is auto recover in this device. 

  • 0 in reply to Shadow He
    Prodigy 20 points
    Input voltage is 12V, I have tried upto 24v but the device seems to be heating up more at 24V.
    Output power is 25W speaker. 8ohm.
    What is the max input peak to peak voltage allowed? Mine goes upto 1.5V RMS.
  • 0 in reply to Sudarshan K
    TI__Mastermind 48740 points

    Hi 

    Sudarshan K said:
    What is the max input peak to peak voltage allowed? Mine goes upto 1.5V RMS.

    The input pin could accept max 6V, but you should use according to your settings. I find in your schematic, the Gain seems set to 26dB, if you input 1.5V rms, it means the output want to give 30V rms. That is too large, considering your supply voltage is only 12V.

    We suggest you could use resistor as the load, and use fixed 1KHz sinewave to test your system first. Use oscilloscope to capture input and output waveform at the same time, it will help you to find the problem and decide the maximum using condition.

  • 0 in reply to Shadow He
    Prodigy 20 points

    What would you suggest for gain setting? Would 24V help or is it to high..24V with transformer load does not even let me start..I tried. At least with 12V I am able to start the amplifier and it starts to hiccup after playing for a few minutes

    Also my ultimate goal is to connect to 100V transformer. Currently based on one of the application notes from TI , It looks like my transformer is saturating and hence device is going to Short ckt protection mode and hence the hiccups.

    Do you know if there a faster mode for support. I am willing to pay for it. This daily back and forth of taking to long for any commercialization plans.

    Thank you for your help.

  • 0 in reply to Sudarshan K
    TI__Mastermind 48740 points

    Hi Sudarshan

    Sudarshan K said:
    Would 24V help or is it to high..24V with transformer load does not even let me start..I tried. At least with 12V I am able to start the amplifier and it starts to hiccup after playing for a few minutes

    If 24V can't start up, it's quite possibly caused by the transformer saturation, maybe your transformer's power ability is low. And for 12V playing for several minutes and hiccup, it's possibly caused by the over temperature, also possible over current. 

    Your schematic connected SD pin and FAULT pin together, the fault would be auto-recovered, that is the hiccup comes from. And for the information we have now, the over current and over temperature is the most possible. You just need to monitor temperature, also capture the output current to make clear which one caused the issue. Then we would able to solve it.

    As you know, if we want a system working correctly, we need to calculate every working point, and test the board to find out if everything works fine. Could you please let me know, in your calculation, what is the target voltage and load value at both input and output side of your transformer? And what is the input signal level at TPA3116D2 input side also the PVCC need to be used? And what is the total output power would be, is TPA3116D2 also the transformer suitable to output such power? If you have answer for all of this question, I'm sure we would easily find out the problem.

    Sudarshan K said:
    Do you know if there a faster mode for support.

    TI have local filed team to support the customer. If you get TI's part from your companies sales or agency, I think they would able to contact them. 

  • 0 in reply to Shadow He
    Prodigy 20 points

    Thanks for the detailed help Shadow He,

    The transformer has been custom designed and manufactured for 8ohm input which for 25watt i of power is 14.14v on primary and 100v on secondary  (400ohm) 

    The most frustrating part is if I supply a pure sine wave 1Vrms input to TPA3112 ( through a 600:600 transformer) from 1khz to 7.5khz, the output from the transformer is perfect .. no chopping , full power etc

    With the exact same setup if i replace pure sine wave with music through a laptop, I am not able to go beyond 6wattts of power before the amp cuts off.

    Any views on this?

  • 0 in reply to Sudarshan K
    TI__Mastermind 48740 points

    Hi Sudarshan

    Sudarshan K said:
    With the exact same setup if i replace pure sine wave with music through a laptop, I am not able to go beyond 6wattts of power before the amp cuts off.

    There's several possibility, all related with transformer, we need to check them one by one.

    1. The music may contains several burst signal. Maybe the average power is quite low, but could have several strong tone that may has very large instant power, cause the transformer saturation for short time. We could try using a 8ohm resistor as the load of TPA3116, see if you could get larger power Playing music.

    2. It's also possible the frequency contains in the music that cause transformer misbehavior. When testing with sinewave, we need to test from 20Hz to20KHz. And it's possible the low frequency would cause trouble. The transformer would be more easily get saturation with low frequency.