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BQ78350-R1: Help 78350-R1 + bq76920

Andrew Buckin
Expert 2130 points
Part Number: BQ78350-R1
Other Parts Discussed in Thread: BQ76920, BQ78350, BQSTUDIO

Hello All,

Help to establish the correct paraneters for bq78350-R1. I have only SMB.
I have BMS 5S bq78350-R1 V1.03 + bq76920.
Rsene 20mR - 1W, current SCD 6,65A  current OCD 4,15А.
1. I set AFE Celll Map to 1F. write.
2. Send FET_EN.
3. Send RESET + Power Off
4. Set DC 21V.
5. Power ON.
6  Boot.
7 Set AOLD HEX to 5C. 320ms, 83mV, write
8 Set ASCD HEX to 8C 100uс 133mV,write.
9 Send RESET.
10 connected load 2A. Load - "ON".
BMS cut off the batteries. :( :(
11 Load off.
Why does not BMS hold the load?

Thank you

Andrew

  • 0
    TI__Guru* 76230 points
    hi Andrew,
    Someone would look into this and get back to you soon.
    thanks
    Onyx
  • 0 in reply to Onyx Ahiakwo
    Expert 2130 points
    For me BQ78350-R1 is new chip. :)
    I have an electronic load with two modes normal and slow.
    I set it to slow mode and the BMS started.
    In the normal mode, flowing a very high inrush current. 20A, 200us.
    I set ASCD HEX to 9C 400us 133mV. BMS work correctly.
    Now I will look for a high inrush current. :(
    Me power path.
    Power supply(21V, 8A), BMS(Rsens + 2xFET), electronic load.

    Andrew.
  • 0 in reply to Andrew Buckin
    Expert 2130 points
    Has TI an example (PDF) of custom BMS bq78350 + BQSTUDIO.
  • 0 in reply to Andrew Buckin
    Mastermind 8415 points
    Hi Andrew,
    This might seem obvious, but have you calibrated your BMS?
    In BQ Studio, You should first set the sense resistor value.
    Click on the Data Memory button at the top. The sense resistor should be in the Settings or Calibration section on the left (I am away from work so I am going off my memory here). it doesn't have to be very precise at this point.
    Once, you have set that value, set the thresholds to a high value (since you are in a controlled environment, nothing should go wrong). You should also set the over-current protection (OCC and OCD, which are additional current settings stored in t he BQ78350, as opposed to SCD and AOLD which are stored in the BQ769x0). On the left side, you should a Protection category.
    Then, click on the Calibration button at the top of BQ Studio, and you can then calibrate the current to set the zero and slope.

    If that still doesn't work, check the Registers View to see which condition does not allow you to discharge.

    Regards,
    Michel