BQ78Z100: OCD/ASCD delay tolerance

Chen Jia

Part Number: BQ78Z100

To whom it may concern:

We are using BQ78Z100 on a single cell battery. The OCD is set to 2.6V, 2s. During the verification test, the delay is tested as 3.8s when 2.6A applied, and 3.5s when 2.7A applied. So could you help to check the reason of this big tolerance on the delay?

Also the ASCD shows a longer delay. It was set at 22.2A with 244us delay, but tested as ~500us as shown below. The blue line is the MOSFET gate signal, and yellow is the output voltage, and purple is the current.

So is this normal to have this delay tolerance for this IC?

Thank you!

Chen

over 2 years ago

0 Jose Couso over 2 years ago

TI__Mastermind 27321 points

Hello Chen,

For Firmware (FW) protections, 1 or 2 seconds of delay is normal. This is because the FW protections are not directly based on clock cycle, but when the bq78z100 runs the protection check mode. These are run periodically.

Regards,
Jose Couso

0 Chen Jia over 2 years ago in reply to Jose Couso

Intellectual 850 points

Hello Jose:

Thanks for your reply!

How about the AFE protections? The delay is also higher, even double of the setting delays.

Thanks.

Chen

0 Jose Couso over 2 years ago in reply to Chen Jia

TI__Mastermind 27321 points

Hello Chen,

The bq78z100 reads AFE values at certain intervals, the delay is expected.

I would double check the way the protections are read in the code. Maybe extra delay is added from the way the code is written, but delay is expected.

Please attach your configuration file to check AFE protection configurations.

Regards,
Jose Couso

Power management

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BQ78Z100: OCD/ASCD delay tolerance