BQ76940: VC1 pin to VSS pin will short in 24cell application

Gabriel Wang1

Part Number: BQ76940
Other Parts Discussed in Thread: BQ76930

Tool/software:

Dear Expert

It's like this, we have a BMS solution that uses BQ76930+BQ76940 cascaded for 24S. However, there have been high serial numbers of BQ76940 chips that have been damaged to end customers. The damaged situation is that the VC1 pin to VSS pin resistance of the chip is only a few tens of ohms.

over 1 year ago

0 Luis H. S. over 1 year ago

TI__Mastermind 42060 points

Hello Gabriel,

Do we know in what conditions did this damage occur? Was it during short-circuit, or some other case?

What are the number of failures?

Best Regards,

Luis Hernandez Salomon

0 Gabriel Wang1 over 1 year ago in reply to Luis H. S.

Genius 4725 points

Dear Luis

The damage occur during take load testing .

The failure rate is 10/650=1.5% ,and the discharging current is 150A peak .

0 Luis H. S. over 1 year ago in reply to Gabriel Wang1

TI__Mastermind 42060 points

Hello Gabriel,

Thanks for the information. Has this been able to be recreated in the lab? I am wondering if it can be replicated. The pins have an abs differential max of 9-V, so I wonder if somehow that became damaged. A Zener diode on VC0 and VC1 to limit the voltage transients likely would help keep these more robust.

Best Regards,

Luis Hernandez Salomon

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BQ76940: VC1 pin to VSS pin will short in 24cell application