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BQ78350-R2-DEVICE-FW: Understanding IPScale

Pietro Vignali
Intellectual 925 points

Part Number: BQ78350-R2-DEVICE-FW

Hello,

We have just designed a new BMS for a 7S pack for a special power tool, using bq78350-R2.
We need to set some protections like OCD Threshold and SOCD Threshold around -40A and -50A, but these values exceed the max allowed programmable value of -32768mA.

I understand the role of the IPScale parameter, but it is unclear the usage:

If I set IPSCALE = 0x01 (bit15-12= 0001), I understand that some readings are scaled by a factor of 10^1, but I don't understand which settings need to be saved in the DataFlash scaled by 10, and which not:
- do ALL the current settings expressed in mA need to be scaled ?
- do ALL  the capacity settings expressed in mAh need to be scaled ?

If only a part of the parameters need to be scaled, which one are affected by the IPSCALE ? and which not ?

Thanks in advance.

Pietro

  • 0
    TI__Mastermind 42535 points
    Hi Pietro,

    Your settings in mA need scaling. In the gauge, the IPSCALE implementation doesn't require derived parameters be scaled.
  • 0 in reply to Batt
    Intellectual 925 points
    Hello Batt,
    thanks for the reply , but I don't understand you completely.

    About mA settings:
    Thresholds like Current Deadband, I guess cannot be scaled.
    But for sure I need to scale the OCC and OCD thresholds: instead how to do with the OCC and OCD "Recovery thresholds" if I need them to be as low as 200mA?

    Concerning the "derived parameters", do you mean that the mAh and cWh settings does not need to be scaled ?

    Thanks in advance
    Pietro
  • 0 in reply to Pietro Vignali
    TI__Mastermind 42535 points
    Hi Pietro,

    Wherever a current multiplication is involved, please use scaling there. So, for example all the recovery thresholds have to be scaled since they depend on the reported values. Also, you will also need to scale design capacity etc. What this means is, instead of you having to fake reported current, like say calibrate using 1A and actually say the calibrated current is 100mA giving you a scale of 10, the gauge handles it by itself.