BQ21080：Vsys has no outpu

Hello Hemry,

Thank you for the waveforms. To confidently rule out a BATOCP event and confirm whether the device can communicate when this issue occurs, I need the register dumps as previously requested.

This information is critical for resolving the issue, and I appreciate your efforts in providing it. Let me know if you have any questions or need further clarification.

Best regards,

Alec Lehman

Hi Alec,

The device fails to connect when this issue occurs.

Hello Hemry,

Thank you for confirming that the device is unable to communicate when this issue occurs. At this point, it would be helpful if we could receive one of your boards to investigate this further. Could you please reach out to your FAE and have them assist with sending us one?

Additionally, could you please clarify again whether this issue can be reproduced on all of your boards or if it is limited to just one? I'd like to reconfirm that this is not device-specific but rather an issue that can be reproduced across all of your boards.

I appreciate your patience as we work through this.

Best regards,

Alec Lehman

Hi Alec,

1. Can I provide the PCBA to you for analysis??
The signal line has already been routed out.(Gnd,Vbus,Vsys,Vbat,TS)

2. This issue can be reproduced on certain PCBAs.the probability is approximately 1/50.

Hello Hemry,

1. Yes, please send us a board for analysis. I appreciate you routing the signal lines out - that will be very helpful. Please reach out to your FAE for assistance with coordinating the return, and I'll connect with them on my end as well.

2. Can you confirm if this issue occurs on all boards or only some boards? I just want to ensure that the board you send us is one that shows this issue.

Best regards,

Alec Lehman

1. This PCBA can reproduce the issue.

2. Test condition: Power on for 1 seconds (mouse working,Led Turn on) => Power off for 5 seconds => Power on for 1 seconds, and so on.

Hello Hemry,

Have you tried performing an A-B-A swap to determine if the issue follows the BQ21080 IC?

(A) Remove the suspect IC from the PCB with this issue.

(B) Replace it with a known good IC and check if the issue persists on the original PCB.

(A) Place the suspect IC on a known good board and see if the issue occurs there.

Best regards,

Alec Lehman

1. After replacing with a new BQ21080, the Vsys no-output issue seems to no longer occur.
2. Since the IC has underfill applied, it cannot be re-soldered onto another PCBA after desoldering.
3. The provided PCBA sample with the IC not yet replaced.

Hello Hemry,

Do to the U.S. holidays our responses may be delayed, sorry for the inconvenience.

Sincerely,

Wyatt Keller 

Hi Alec,

Tracking No. is 3331748431, thanks.

Hello Hemry,

Thanks, we will watch for this and let you know.

Sincerely,

Wyatt Keller

Hi Wyatt/Alec,

May I ask if there is any feedback?

Hello Hemry,

I received your board and am looking into it. I'll provide an update tomorrow, 12/5. Thanks for your patience.

Best regards,

Alec Lehman

Hello Hemry,

I received the mouse PCBA and was able to recreate the issue in our lab. I've also reached out to your FAE to start the failure analysis (FA) process. Given that this issue went away with an ABA swap, it seems possible that the root cause could be device damage.

I'll continue investigating this issue and share any findings with you.

Best regards,

Alec Lehman