BQ40Z50-R2: IC enters state where battery cells needs to be disconnected from BQ40Z50-R2 for recovery

Sami Vaara

Part Number: BQ40Z50-R2

Hello,

We had test camp where we noticed about ~40 battery packs (3S 1600mAh) which didn't communicate anymore with main uC. After debugging the issue we noticed that battery cells are ok and we didn't find any issues from BMS PCB/components, BQ40Z50-R2 just didn't turn on. But we noticed that after disconnecting battery cells from BQ40Z50-R2 and then connecting cells back, system recovered and IC became functional and whole battery pack operational.

What could cause this kind of behavior? Chip latches, FW jamming or something else?

During test camp we did drain packs totally empty few times with small current. But some packs we recovered had pack voltage over 12V so it was not empty.

over 4 years ago

0 Sami Vaara over 4 years ago

Prodigy 150 points

Batt1.gg.csv Batt2.gg.csv

0 Wyatt Keller over 4 years ago in reply to Sami Vaara

TI__Guru** 105590 points

Hello Sami,

Sometimes we have seen this kind of behavior with ESD events where the gauge stops communication until there is a power reset. Are the .gg files you shared of the batteries before or after the test? Did any of the permeant failure flags or safety flags get set?

Sincerely,

Wyatt Keller

0 Sami Vaara over 4 years ago in reply to Wyatt Keller

Prodigy 150 points

.gg files are taken out after battery was recovered by disconnecting cells. Permanent flags are not in use.

-Sami

0 Kang Kang over 4 years ago in reply to Sami Vaara

TI__Mastermind 24870 points

Hello Sami,

Can you provide the TS pin measurements via oscilloscope from a pack that does not communicate?

How reproducible is this?

0 Sami Vaara over 4 years ago in reply to Kang Kang

Prodigy 150 points

Hello,

I have no idea how to reproduce this issue, we just get these batteries every now and then.

With TS pin you mean Temperature Sensor pins? Or something else?

-Sami

0 Wyatt Keller over 4 years ago in reply to Sami Vaara

TI__Guru** 105590 points

Hello Sami,

Yes the TS pin is the temperature sense pin. If you see a pulse on the pin it means the firmware is still running, even if communication has stopped.

Sincerely,

Wyatt Keller

0 Sami Vaara over 4 years ago in reply to Wyatt Keller

Prodigy 150 points

Hello,

It seems that FW is not running, there is no pulse in TS pins.

As reference I also measured working battery and there I see about 10ms wide 0.7V pulse.

Regards,

Sami

0 Kang Kang over 4 years ago in reply to Sami Vaara

TI__Mastermind 24870 points

Hello Sami,

That's very strange, can you reproduce this issue on a good pack?

Power management

Power management forum

BQ40Z50-R2: IC enters state where battery cells needs to be disconnected from BQ40Z50-R2 for recovery