TAS5760M: NACK Issue with a couple of TAS5760Ms in PBTL Configuration

Hi Andy-san,

Thank you for your response.

This issue can be resolved if changing I2C device address from 0x6C to 0x6D in PBTL configuration, therefore a couple of TAS5760Ms with PBTL configuration cannot be connected on the same I2C bus.
Have you had a similar experience ?

Best regards,
Kato

Hi Kato,

No, I have not yet heard a similar issue like yours. When the TAS5760M device returns NACK for the 0x6c address, will it return ACK for the 0x6D address? If so, the voltage at the ADR pin is not correctly latched at power-up.

Andy

Hi Andy-san,

Thank you for your support.

TAS5760M returns ACK if setting the 0x6D to TAS5760M as the device address.
So, I don't know why it fails for the 0x6C address.
Could you please give me your advice again ?

Best regards,
Kato

Hi Andy-san,

I have already emailed you about these issues.
Sorry for rushing you, but I will need to inform the root cause and the workaround to our customer today.
Could you please give me your advice ?

Thank you and best regards,
Kato

This issue has been taken care of offline.

Hi Andy-san,

Our customer is continuing to investigate this issue, so I will contact you if I get any updates from him.

Best regards,
Kato

Hi Andy-san,

I have already emailed you about new information.
So could you please give me your advice ?

Best reagards,
Kato

Hi Kato,

When I was digging into this issue, I happened to find out some existing e2e discussion abut the same issue. Let me forward it to you.

Andy

Hi Andy-san,

Thank you for your reply.
I am looking forward to getting that information from you ASAP.

Best reagards,
Kato

Hi Andy-san,

I found out the following post which you mentioned.
Would you recommend to insert "Start Byte" before sending the first writing command if accessing TAS5760M registers via I2C bus after the power-on ?
Please give me your advice as soon as possible.

https://e2e.ti.com/support/amplifiers/audio_amplifiers/f/6/p/318201/2126585

Best reagards,
Kato

Hi Kato,

The post you found is exactly what I saw the other day. The "Start Byte" is actually a fake i2c operation. Based on my test results and the discussions in that e2e thread you mentioned, I would agree to you that it is necessary to fix the NACK issue right after TAS5760M is powered on.

Andy

Hi Andy-san,

Thank you for your reply.

Could you please tell me the root cause on this NACK issue ?
In addition, does it mean that there is no the workaround as needing to fix TAS5760M right ?

Best regards,
Kato

Hi Andy-san,

Sorry for rushing you, but I will need to inform the root cause and workaround to our customer ASAP.
Note : There was a typo in the above post and I fixed it.

Best regards,
Kato

Hi Kato,

As you may know, the workaround is easy, which is to send the i2c command again since this issue only happens to the first write i2c command after power-on.

As for the root cause, I already sent out emails to our design team and if everything goes well, I will be able to talk to them shortly.

Andy

Hi Andy-san,

Thank you for your quick response.
I understood the workaround but I am looking forward to getting the root cause from you ASAP.

Best regards,
Kato