BQ40Z50-R2: Shutdown Issue

Zhihan Zhang

Part Number: BQ40Z50-R2
Other Parts Discussed in Thread: BQSTUDIO

Hi TI Team,

Recently I found there is some issue when entering voltage based shutdown mode. What I did was using 2A electronic load to discharge the battery all the way until IC completely enters shutdown mode. And it appears that shutdown will recover for couple times before IC completely shuts down. Below is the waveform for P+ voltage (yellow) and current (pink) vs time. Can you please kindly review and explain why there is such on and off bahavior for entering shutdown mode?

Also attach gg.csv and bqStudio log for review.

597 shutdown 2.xlsx shutdown.gg.csv

Thanks,

Zhihan

over 4 years ago

0 Nick Brylski over 4 years ago

TI__Mastermind 19195 points

Hi Zhihan,

This looks like normal behavior, the protection for CUV is getting triggered around 2.5V / cell.

Best regards,

0 Zhihan Zhang over 4 years ago in reply to Nick Brylski

Expert 1100 points

Hi Nick Brylski,

Sorry I forgot to attach SMBus log. Actually from SMBus log, what I can see is that shutdown trips instead of CUV because we set shutdown voltage higher than CUV threshold. However, it looks like the IC recovers from shutdown for couple time until it's completely shutdown. At that moment, I can get any log data. So I'm wondering what behind is interfering the shutdown process?

Thanks,

Zhihan

8345.597 shutdown 2.xlsx

0 Nick Brylski over 4 years ago in reply to Zhihan Zhang

TI__Mastermind 19195 points

Hi Zhihan,

If you set CUV higher than the SDV, you can configure the CUV for hysteresis and avoid this behavior. (CUV recovery threshold)

Best regards,

Power management

Power management forum

BQ40Z50-R2: Shutdown Issue