LM4670: LM4670SD/NOPB Can't output Sound

Hoang Anh

Intellectual 555 points

Part Number: LM4670

Hi Everyone.

I have designed PCB based LM4670SD/NOPB datasheet, for more information please see attached file.

My MCU can communicate, read and write to LM4670, but my speaker can't output Sound.

Everyone can help me detect my problem

Thanks and best regards.

My schematic and logfile test with LM4670SD

over 5 years ago

0 Luis Fernando Rodriguez S. over 5 years ago

TI__Guru* 84915 points

Hi, Hoang,

Do you have details about the speaker output when you disable the Shutdown pin? I mean, is there any activity at the output when you unmute the device?

What is the VBAT_AUDIO level that you are using?

Best regards,
Luis Fernando Rodríguez S.

0 Hoang Anh over 5 years ago in reply to Luis Fernando Rodriguez S.

Intellectual 555 points

Hi Luis !

Thanks you for your reply.

I have try to setup Shutdown pin to hight or low but the output still same result "not output sound".

About VBAT_AUDIO this is 3.2V.

So could you tell me

1.How to check the output? We can using ossilocos ?

2.Do we need T filter in the output, same my schematic?

3.Do you have any reference schematic using LM4670D beside schematic in datasheet. If you have, could you send them to me, it will help me tremendously to detect my problem.

Thanks and best regards.

0 Hoang Anh over 5 years ago in reply to Hoang Anh

Intellectual 555 points

Hi Luis Fernando Rodríguez S.

I'm spending a lot of time to detect where is problem, but I can't.

I'm waiting your support to solve my problem.

Thanks And Best Regards.

0 Luis Fernando Rodriguez S. over 5 years ago in reply to Hoang Anh

TI__Guru* 84915 points

Hi, Hoang,

Sorry for the late response, we had a holiday this week and the support was delayed.

I have some recommendations for your LM4670 circuit.

Could you remove all the input components except the C34, R10, R11 and C42 components? This is to leave the circuit exactly like shown in figure 29 of the datasheet. Could you also send me a picture of the input signal that you are sending to the input?

Could you also remove the output capacitors C70, C72 and C74? Do you have the same results?

Thank you.

Best regards,
Luis Fernando Rodríguez S.

0 Hoang Anh over 5 years ago in reply to Luis Fernando Rodriguez S.

Intellectual 555 points

Hi Luis.

Thank you for your support.

I have remove some component as your required.

Then it have output sound. But sound verry low, this same head phone.

I try to fix program to improve output sound.

If it not have good serult, i will come back here and waiting your support.

Thanks and best regards.

0 Luis Fernando Rodriguez S. over 5 years ago in reply to Hoang Anh

TI__Guru* 84915 points

Thank you for your feedback,

I will be waiting for your results.

Best regards,
Luis Fernando Rodríguez S.

0 Luis Fernando Rodriguez S. over 5 years ago in reply to Luis Fernando Rodriguez S.

TI__Guru* 84915 points

Hi, Hoang,

I will close this E2E thread for now. But please feel free to post your results and observations when you have them.

Thank you.

Best regards,
Luis Fernando Rodríguez S.

0 Hoang Anh over 5 years ago in reply to Luis Fernando Rodriguez S.

Intellectual 555 points

Hi Luis.

After the output have sound but it very small. I have spend many time try to make sound bigger but still now not success.

I hope you give me some idea to improve the output sound.

Thanks and Best Regards.

Hoang Anh.

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LM4670: LM4670SD/NOPB Can't output Sound