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BQ78350-R1: FET and LED controle not possible in normal operation

mschwend
Prodigy 50 points
Part Number: BQ78350-R1
Other Parts Discussed in Thread: BQ76930, BQ78350

Hi,

I'm currently working on a BMS for 8s1p configuration, using the BQ76930 as AFE and the BQ78350 as Host. It fails trying to controle the FETs using KEYIN (low active) and the LEDs using button in normal operation.

Some related configurations I did:

Settings.Configurations.FET_options = 0x 00 22;

Settings.Configurations.LED_configuration = 0x04;

There are no faults:

ManufacturerAccess() 0x0051 SafetyStatus = 0x 00 00 00 00;

ManufacturerAccess() 0x0053 PFStatus = 0x 00 00 00 00;

BatteryStatus() 0x16 = 0x 00 C0;

Operation Status:

ManufacturerAccess() 0x0054 OperationStatus = 0x 80 00 61 01;

--> says: Device is UNSEALD, System is present  (PRES-pin is connected to gnd), KEYIN has been detected, external FET controle through SBS not possible

Why is the DSG FET still inactive? Why is it not possible to turn on the LED bar display?

The only way to enable the controle of FETs and LEDs is to make use of ManufacturerAccess() commands (0x0022 for FET and 0x0027 for LED) or by writing the required bits to Mfg Status Init and doing a reset().

 

Any help would be great!

  • 0
    TI__Guru* 76230 points
    The fets has to be enabled using that command i.e (0x0022). Are you expecting the fets to be on by default?
    thanks
    Onyx
  • 0 in reply to Onyx Ahiakwo
    Prodigy 50 points

    That's right, ManufacturerAccess() 0x0022 disables/enables controle of the FETs by the firmware and sets ManufacturingStatus()[FET_EN]. [TRM 17.2.18]
    That toggling command will only set the RAM data, wich means the conditions set by this command will be cleard if a reset or seal is issued to the gauge. [TRM 12.1]
    It's possible to safe that conditions ( ManufacturerStatus() ) to data flash by writing them to Mfg Status Init. [TRM 12.1]
    SLUA726A ("Using the bq78350") says to clear Mfg Status Init when preparing for production. [section 5.0]

    Conclusion:
    ManufacturerAccess() writes to RAM (cleared on reset or seal).
    Mfg Status Init is data flash but should be cleared during production.

    Thats the problem: How can I permanently enable controle of the FETs?

  • 0 in reply to mschwend
    TI__Guru* 76230 points
    enabling the fets should be part of your production process.