BQ76942: MOSFET Damage During Short Circuit Test

Tom Tsao

Part Number: BQ76942
Other Parts Discussed in Thread: BQ40Z50,

Tool/software:

Hello TI Support Team,

I encountered an issue where the MOSFET was damaged during a short circuit test while using the BQ76942. However, when performing the same test with the same MOSFET using the BQ40Z50, no damage occurred.

Could you please help check if there is any issue with my circuit schematic?

Thanks!

5 months ago

0 Kian Lin 5 months ago

TI__Expert 4220 points

Hi Tom,

You can refer to this thread to debug

How to debug FET failure resulting from short-circuit testing

Let me know if you find more clues.

Quick questions on you SCHs:

What's the Ground R24 connect to? Is it the PACK- terminal?
Can you show the Cs and Rs value in your SCHs?

BRs

Kian

0 Tom Tsao 5 months ago in reply to Kian Lin

Expert 1850 points

Hi Klan,

What's the Ground R24 connect to? Is it the PACK- terminal? => Yes,it is connected to Pack- terminal.
Can you show the Cs and Rs value in your SCHs? => Cs are 0.1uF and 100pF ,Rs is 0.002Ω.

Is there anything incorrect about the CHG and DSG MOSFETs on my schematic?

Thanks!

0 Kian Lin 5 months ago in reply to Tom Tsao

TI__Expert 4220 points

Hi Tom,

You can refer to Schematic — TIDA-010208 for the Rs and Cs value.

Your schematic is quite simple, comparing to our recommended circuit, without extra protection circuit. I am not sure which overstress damage your MOSFET before getting more clues. You can try to modify your schematic to see if any improvement.

BRs

Kian

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BQ76942: MOSFET Damage During Short Circuit Test