BQ76925: Clarification on Circuit Breakers in SLUA707 Reference Design

Prashant Kumar Singh

Part Number: BQ76925

Tool/software:

Hello TI team,

I'm working on a custom battery management design using SLUA707 ("3 to 6 Cells Battery-Management System Based On bq76925 + MSP430G2xx2") as a reference. While reviewing the schematics in the application note, I noticed that various components labeled as CB1, CB2, ..., CB10 etc. are marked as "CIRCUIT BREAKER" but are not described further in the documentation.

Could you please clarify:

What function these CBx elements serve in the reference design?
Are they placeholders for physical circuit breakers or symbolic representations for test/debug points( if so can i use 0 ohm resistors in place)?
Are there recommended part numbers or implementation guidelines for these circuit breakers for protection or system isolation purposes?
Should I include these CB components in my own design, and if so, under what use-case conditions?

Understanding the role and selection criteria of these CBx components will help me design a safer and more robust BMS system.

Thanks in advance for your support!

Best regards,
Prashant Singh

5 months ago

0 Luis H. S. 5 months ago

TI__Mastermind 42060 points

Hello Prashant,

The people who created these designs are no longer at the company. I believe these serve the purpose of a jumper. So I'd suggest to use 0-Ohm in its place.

I do not believe you require these.

Best Regards,

Luis Hernandez Salomon

0 Prashant Kumar Singh 5 months ago in reply to Luis H. S.

Prodigy 10 points

Thanks for the clarification Luis, just another small doubt if u could clear it would be helpful.

from what i can understand the first image from the datasheet connects the most -ve end of the battery pack to the ground which then goes to the Rsens however in the app note the VC0 that is the most negative end doesnt seem to be connected to the gnd here so the BATT- doesnt connect to the VC0 in that case.

Could you clear that issue?

+1 Luis H. S. 5 months ago in reply to Prashant Kumar Singh

TI__Mastermind 42060 points

Hello Prashant,

BAT- will always connect to VC0. So even if it is not on the board, there will be two cables that connect to BATT- and VC0 from the BAT- terminal.

Best Regards,

Luis Hernandez Salomon

0 Prashant Kumar Singh 5 months ago in reply to Luis H. S.

Prodigy 10 points

Thanks for the clarification Luis.

By the way the application note mentioned supporting documentation like BOM and layout designs however, i couldn't find these anywhere. Are they not available anymore or is there some other issue?

0 Luis H. S. 4 months ago in reply to Prashant Kumar Singh

TI__Mastermind 42060 points

Hello Prashant,

You can see the BOM/layout in the EVM user guide. However, I see that the Gerber shares have been shared in the past:

https://e2e.ti.com/support/power-management-group/power-management/f/power-management-forum/190482/bq76925evm-gerber-files-available

Best Regards,

Luis Hernandez Salomon

Power management

Power management forum

BQ76925: Clarification on Circuit Breakers in SLUA707 Reference Design