BQ77915: Bq77915: when ever 10K NTC is connected IC is not working

Janardhanbabu Marri

Part Number: BQ77915

Greetings,

this is janardhan, I am using the BQ77915 battery protection IC for our drone battery BMS design. initially, on the bench test, the IC was working as expected and after that, I integrated the BMS circuit with the Battery pack, which worked 2 times. then again I connected the load to the battery with a power meter to observe the load current, and then the IC stopped working. when I check the voltage across VDD to ground I observed if 10K NTC is connected to the circuit then the voltage across VDD is 4.182V, if the 10K NTC is removed then the battery voltage appears. I am using 2 x BQ77915, both in 3S configuration. the issue is only with the 2 IC which is connected to the battery ground.

over 1 year ago

0 Maxwell Verboncoeur over 1 year ago

TI__Mastermind 24260 points

Hi Janardhan,

Could you share your schematic for me to review?

Regards,

Max Verboncoeur

0 Janardhanbabu Marri over 1 year ago

Prodigy 115 points

Hi Sir,

Greetings,

Please find the attached link below for the schematic, the attached circuit is for 3S configuration and this board can be stackable with other boards using SMD jumpers. I have used 2 boards(6S configuration with reference). Today I replaced the issue IC with a new one, now the board is working fine. But I couldn't find why the IC failed.

BQ77915 3S board

Regards,

Janardhan

0 Maxwell Verboncoeur over 1 year ago in reply to Janardhanbabu Marri

TI__Mastermind 24260 points

Hi Janardhan,

We are not able to open Google drive links for security reasons. You should be able to directly attach the schematic as a PDF to an E2E message using the Insert option at the bottom.

I recommend checking your connections for each device. It could be that a negative voltage is being introduced when the ICs are stacked.

Regards,

Max Verboncoeur

0 Janardhanbabu Marri over 1 year ago in reply to Maxwell Verboncoeur

Prodigy 115 points

Dear Sir,

Please find the attached PDF for schematic.

Regards,

Janardhan.

Schematic_BQ77915-3S-board_2024-02-16.pdf

0 Maxwell Verboncoeur over 1 year ago in reply to Janardhanbabu Marri

TI__Mastermind 24260 points

Hi Janardhan,

Do you have a schematic with both ICs stacked and how the two are connected? I'm assuming some of these components are not populated depending on if it is the upper or lower device, but it would be helpful if I could see how the board is actually populated.

Regards,

Max Verboncoeur

Power management

Power management forum

BQ77915: Bq77915: when ever 10K NTC is connected IC is not working