BQ40Z50: High Shutdown Current on bq40z50 for 4s BMS in shutdown mode

Suslik Shvarckopf

Prodigy 10 points

Part Number: BQ40Z50

Tool/software:

Hello Texas Instruments Support Team,

I am using the bq40z50 chip on one of my 4s BMS boards.

In Shutdown mode, the supply current is 730µA, which does not match the values in the documentation at all.

The consumption drops to 60µA when I desolder the 100-ohm resistor connected to the VCC pin.

However, the chip stops responding via SMBus in this case. This is strange because I understood that

VCC is an auxiliary supply and the chip should be able to operate without it, but in practice, this is not the case.

I have tried flashing different firmware versions, but nothing changes.

Could you please advise what might be causing such high current consumption?

4 days ago

0 Alan Frias 3 days ago

TI__Mastermind 27405 points

Hello,

This question has been assigned and will be reviewed by someone on the team when possible. In the meantime feel free to attach any associated .log/.gg/test files from this project.

Thank you,
Alan

0 Suslik Shvarckopf 1 day ago in reply to Alan Frias

Prodigy 10 points

Thanks, but I have already solved the issue:

I wasn't using the PCHG pin and, for some reason, pulled it up to GND via a 
10kOhm resistor. I also used software to use a CHG-FET as a PCHG-FET.  
Because of this, the bq40z50 consumes 670µA more in shutdown mode. 
I removed the resistor and everything is fine. 

But I still have a question regarding shutdown mode: 
is it possible to enter full shutdown mode with range (10-17)V voltage applied to the PACK+?

Power management

Power management forum

BQ40Z50: High Shutdown Current on bq40z50 for 4s BMS in shutdown mode