BQ40Z50-R1: Cell thermal fuse open

Sidney Tsou1

Part Number: BQ40Z50-R1
Other Parts Discussed in Thread: BQ40Z50

Hi,

We have an application use bq40z50R1 and once a while we notice one of thermal fuse in the cell (3 cells in parallel) always open. (The first connected cell) For this application; we solder 3 cells on the PCB before we programming the bq chip.

Another application we have; we actually program bq first then solder the batteries and I never see any single thermal fuse tripped at the few thousand builds.

My question is what exactly sequence is correct? Programming then soldering the cells or doesn’t matter.

Sidney

over 6 years ago

0 Onyx Ahiakwo over 6 years ago

TI__Guru* 76230 points

pls follow the method that the fuse didn't trip., ie programming the device first

thanks
Onyx

0 Sidney Tsou1 over 6 years ago in reply to Onyx Ahiakwo

Prodigy 30 points

Hi Onyx,

Just curious is any document actually talking about programming bq should go first before cell connect? If I understand correctly, does that mean non-programmed bq could provide unstable state to create a potiential issue if we connect the cells first?

Thanks,

0 Onyx Ahiakwo over 6 years ago in reply to Sidney Tsou1

TI__Guru* 76230 points

Hi Sidney,
see attached document below- it was written for the earlier gen device to the bq40z50 but still applicable.
www.ti.com/.../slua391.pdf

thanks
Onyx

0 Sidney Tsou1 over 6 years ago in reply to Onyx Ahiakwo

Prodigy 30 points

Hi Onyx,

Appreciate that document, that helps a lot.

Sidney

Power management

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BQ40Z50-R1: Cell thermal fuse open