BQ40Z80: How do we base the overtemp on external thermistors only

Jamie Milliken8

Part Number: BQ40Z80

Tool/software:

Hello,

In our BQ40Z80 application, we have enabled the internal temp measurement, as well as two external thermistors on TS1 and TS2. We would like to be able to read the internal temperature for logging, but do not want this to be factored into the overtemp and undertemp protections. Only the two thermistors attached to the cells should control the protections. So how do we set this up in the registers? Specifically, my questions are:

If we have three temperature sources enabled, are they all contributing to protections. Or can I select which ones are actively involved.
How is the protection actually triggered? There is a setting in DA Config for min/max/avg, but this seems like it is just for reporting. Does this also affect how it is calculating thresholds internally. Or is, for example, the hottest thermistor always going to trigger overtemp?

Thanks,

Jamie

9 months ago

0 Adrian 9 months ago

TI__Mastermind 37761 points

Hello,

This week is a holiday in America, we will get back to you next week.

Regards,

TI BGP Team

0 Anthony 9 months ago in reply to Adrian

TI__Mastermind 28480 points

Hi Jamie,

Jamie Milliken8 said:
If we have three temperature sources enabled, are they all contributing to protections. Or can I select which ones are actively involved.

If TS1 and TS2 are enabled and TInt is disabled, then the protections should only trigger based on TS1 and TS2. However, disabling TInt will completely remove it from the gauging calculations that the device completes. You will still be able to read the internal temperature at this time even if disabled.

Jamie Milliken8 said:
How is the protection actually triggered? There is a setting in DA Config for min/max/avg, but this seems like it is just for reporting. Does this also affect how it is calculating thresholds internally. Or is, for example, the hottest thermistor always going to trigger overtemp?

Each temperature protection has a specific list of conditions that need to be met before triggering. Since each temperature sensor (if enabled) needs to be deemed as a Cell Temperature reading or FET Temperature reading, based on how these are set can trigger different protections. In the protection below, this will rely on the Maximum Cell Temperature reading (since multiple can be enabled) to trigger this protection:

Regards,

Anthony

0 Jamie Milliken8 9 months ago in reply to Anthony

Prodigy 230 points

Thank you. I have a follow-up question. Is it possible to set different limits for tripping for each sensor? For example, we would like to limit cell temperature to 50C, but it would be fine for FETs and IC to run hotter than that. However, if we enable the internal sensor, the system will trip when it reaches 50C, but cells are still cool enough to charge. Any solution for this, or do we just have to leave Int and FET temps out of the calculation?

0 Anthony 9 months ago in reply to Jamie Milliken8

TI__Mastermind 28480 points

Hi Jamie,

The temperature protections are divided into ones that are controlled by the FET labeled sensors, and ones that are controlled by the cell labeled sensors. For example, you can set the Overtemperature in Discharge protection, which is controlled by the cell labeled temperatures to 50C, but you can also set the Overtemperature FET Protection to a higher value and they will not interfere.