TPA3116D2: DC at output / Heart beat sound

Hello,

Can capture an output waveform where you are seeing this noise.

best regards,

Luis

Hi check this video

Attached  output wave form on 8ohm Load with no input connected 

Hello Shravanth,

Can you also provide the PWM output Waveform for both channels. For your manufacturer can you confirm that there hasn't been any component changes due to IC shortage/vendor limitation. Also can you confirm where these IC's were procured from.

best regards,

Luis

Hi you can check the video below when powering up, Scope probes before Inductors and image probe after inductors

We have not changed any components yet, all components are the same as shown in the circuit & as IC was not in stock with mouser or digikey we have get them from local vendor. 

Voltages of TPA3116D2 

At pin 4,5,11,12 - 3V 

pin 7 - 7V

pin 8 - 1.2V

Hello Shravanth,

Can you try replacing the input capacitors, leaky input capacitors can result in dc outputs manifesting.

best regards,

Luis

Hello Luis,

We have tried with different brands of input caps 1uf, we have also tried by changing bootstrap 220nf caps but the results are the same.

Hello Shravanth, 

Do you have an older board for correlation? Also to confirm is this seen on multiple boards and multiple devices? Do you have any older devices to rework this board with.

best regards,

Luis

Hi Shravanth,

Did you check Fault pin waveform? is there any fault triggered?

I suggest you can short audio input to GND through 1uF caps, and check if the issue is gone or not. If so, the noise is coming from audio source.

Regards,

Derek

Hi Yanming,

Checked with Both Left and Right Inputs to GND through 1uf Caps but problems is still There.

Hi Shravanth,

Did you check Fault pin waveform and output pin waveform when short input? 

Regards,

Derek

Hi Yanming,

Test conditions with 16V DC, output waveform is same when input is short or open, voltage at Pin 2,3 - 14V. and no waveform at Fault pin 3

Hi Luis,

Tried the same IC on Older board, problem is same. ordered TPA3156D2 - 92nos from TI store to check if the IC or PCB Problems.

Hi Shravanth,

What's the waveform of your picture? which pins?

Did you remove the load and check again?

Regards,

Derek

Hi Yanming,

Those are output waveforms without load.

Hi Shravanth,

please remove LC filter and double check again.

Do you have EVM board? Could you check on EVM board?

Regards,

Derek

Hi Yanming,

Here is the waveform without LC filter & Load, I don't Have EVM but i have an OLD working board with me.

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Hi Shravanth,

It is very strange, without LC filter, the output waveform should be PWM signal.

Old board can work well, right?

I suggest you can compare the boards, and do A-B-A change test.

Regards,

Derek

Hi,

Test DC Voltage - 12VDC

TPA3116 Working Board (PWM) - Same on output pins 

Test Voltages of Working OLD Board

At pin 4,5,11,12 - 3V 

pin 7 - 7V

pin 8 - 1V

Test Voltages of Working New Board

At pin 4, - 2.7 to 3V (fluctuating)

Pin 5,11,12 - 3V 

pin 7 - 7V

pin 8 - 1V

New Board on Pin 29

New Board on Pin 20,  21, 27

Hi Shravanth,

The waveforms of the old and new boards were all on idle status? right?

If so, the new board PWM duty cycle is not correct. I saw your SCH, you set BD mode (Pin #1 connected to GND) , so idle PWM duty cycle must be 50%.

Regards,

Derek

Hi Yanming,

Yes both Boards are Idle, No input or output connected. what might be the problem? any passive component leakage or PCB or Chip?