TAS5717: TAS5717 about the headphone issues

Mickey Zhang

Genius 12080 points

Part Number: TAS5717

Hi Team,

The customer is using TAS5717. There is not any noise when the customer uses the speaker to output. But there is much noise when the customer uses the

headphone to output. Even if the customer change another headphone, there is still much noise. The attachment is the customer's schematic.

J5 is connected to the lines of the headphone. The HP_DET port is the detection port that detect if the headphone be inserted. P7 is output to the speaker.

Can you help me to solve the issue?

PA(1).pdf

Best Wishes,
Mickey Zhang
Asia Customer Support Center
Texas Instruments

over 7 years ago

0 Alex Bhandari-Young over 7 years ago

TI__Mastermind 25845 points

Hi Mickey,

The schematic looks good to me. Would you be able to provide the waveform of the noisy headphone output and the register config used by the customer?

Regards,

Alex

0 Mickey Zhang over 7 years ago in reply to Alex Bhandari-Young

TI__Genius 12080 points

Hi Alex,

Thank you for your reply. The register configuration is as follows:

1. Initialization:

The registers The registers value

0x1B 0x00

0x04 0x05(24bit I2S mode)

0x05 0x00

2. The 0x05 register value is changed to 0x13 when the headphone is inserted. The 0x05 register value is changed to 0x00 when the headphone is pulled out.

3. The 0x02 register is 0x00 if its value is not 0x00.

The attachment is the waveform for the left channel and the right channel of the headphone. The noise does not change as the sound becomes larger.

And the noise is always exist even if there is no sound source.

0 Alex Bhandari-Young over 7 years ago in reply to Mickey Zhang

TI__Mastermind 25845 points

Hi Mickey,

Thanks for the info. Have you measured the frequency of the noise? Also are you able to replicate this issue on the EVM?

I have just ordered an EVM and will try it on my end once I receive it, but if you are able to test on the EVM we may be able to get to the bottom of this issue more quickly.

Thanks,

Alex

0 Mickey Zhang over 7 years ago in reply to Alex Bhandari-Young

TI__Genius 12080 points

Hi Alex,

Sorry, I don't the EVM board. I will wait for your reply and I will verify the frequency of the noise with the customer.

0 Mickey Zhang over 7 years ago in reply to Alex Bhandari-Young

TI__Genius 12080 points

Update:

The noise frequency is about 80HZ. The test waveforms is in the attachment. Please check the attachment.

0 Alex Bhandari-Young over 7 years ago in reply to Mickey Zhang

TI__Mastermind 25845 points

Hi Mickey,

I wanted to give you an update. I am still waiting on the EVM to be delivered so I have not had a chance to test this yet. I am aiming to be able to get back to you next week.

Thanks for the patience on this. Please let me know if there is any additional information from the customer on your end.

Regards,

Alex

0 Mickey Zhang over 7 years ago in reply to Alex Bhandari-Young

TI__Genius 12080 points

Hi Alex,

Thank you for your help. I will wait for your reply.

0 Alex Bhandari-Young over 7 years ago in reply to Mickey Zhang

TI__Mastermind 25845 points

Hi Mickey,

I tested this on the EVM and I did not observe the 76kHz noise that you show in your screenshot. I did observe high frequency noise (see screenshot below -- yellow is the PWM waveform and blue is the output at the headphone) from the switching of the device (280kHz).

Here is a screenshot when I play a 1khz sine wave through the headphones

This higher frequency noise is expected using the headphones because the EVM design for the headphones uses a 1st order RC filter vs. a 2nd order LC filter and differential signal on the speaker output. However, these higher frequencies are outside the audible range. Is the problem you are trying to solve for the customer an audible noise issue? If you can hear audible noise using the headphones, then it will not be the 76khz noise because this is too high frequency.

Thanks,

Alex

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TAS5717: TAS5717 about the headphone issues