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Original question:

BQ4050: FET is enabled but charging and discharging doesnt work

BQ4050: DISCHG_FET is not working

himavanth reddy
Prodigy 245 points
Part Number: BQ4050
Other Parts Discussed in Thread: EV2400

Hi,

I am working on the BQ4050(BMS controller).

I need to implement a battery configuration with 3S-2P.

These are some necessary parameters to set as presets in my opinion.

Design capacity, Device Chemistry, Cell overvoltage, Cell Undervoltage, Cell Shutdown voltage, Over Current in CHG and DCHG mode, Safety overvoltage.

Hardware setup:

Ev2400 connected with a power supply

Host system connection with EV2400

SMB SCL - SMBC

SMB SDA - SMBD

SMB VSS -  PACK-

GND - SYS_PRES

These are my register values:

My questions are:

1. Is there any need for parameters to set other than those things what I mentioned earlier?

2. I am not able to enable the discharge FET?

Note:

Even though there are commands in the commands panel, those are not working in this case(they are not able to make changes in hardware). 

Thanks& Regards

- Himavanth

 

  • 0
    TI__Mastermind 42535 points
    1. Yes, you will need to first characterize the cell and get the CEDV parameters before you start gauging.
    2. Please send the FE_EN command. Your fets are not enabled as seen in manufacturing status.
  • 0 in reply to Batt
    Prodigy 245 points

    Hi Batt,

    Thank you for your reply,

    Can I have a clear picture of, how to characterize the cell?

    As you mentioned in the earliest reply I do send the FE_EN command which you can find on the command log panel.

    I send a set of commands after the FE_EN command like DSG_FET_TOGGLE & CHG_FET_TOGGLE and I observe the terminal voltage each of the above cases but there is no difference at all.

    Note :

    PRECHG_FET is working in all the above cases.

    some commands like DEVICE_NUMBER, DEVICE_VERSION and LED_TOGGLE are working fine and replying the same.

    FET_EN command was not able to make respective commands on the registers which you can find in the picture above.

    please help me out to get out of this problem.

    Thanks & regards

    himavanth

  • 0 in reply to himavanth reddy
    TI__Mastermind 42535 points

    Himavanth,

    Your FET is enabled. You can clearly see that FET_EN is set in manufacturing status register. However you have fuse asserted. Drive the fuse pin low. You should be able to chg or dsg.

  • 0 in reply to Batt
    Prodigy 245 points

    Hi Batt, 

    Thank you for your reply.

    As you mentioned in your reply FET's are in on the condition,  I can understand that by CHG_TEST, DSG_FET & PCHG_FET(as these coloured green. i.e HIGH) in manufacturing status.

    1. What about the FET_EN(that should be HIGH as of my knowledge, if not what is the case?) in the manufacturing status ?.

    2. I tried set of commands to toggle DSG and CHG fets but the terminal voltage is the same in all cases, is it issue with the grounding the fuse?

    Thanks & regards

    -Himavanth

  • 0 in reply to himavanth reddy
    TI__Mastermind 42535 points

    1. Yes. It should be 1.

    2. Yes.

  • 0 in reply to Batt
    Prodigy 245 points

    Hi Batt,

    First of all, Thank you very much for your reply.

    We are also suspecting that the same issue we are facing because we made a single change from the custom circuit bq4050, and uses directly one our design that too because of the lack of availability of chemical fuse.

    My EV2400 kit is not detecting on PC so I am not able to come to a conclusion that solution can work for me.

    I found that one of IC on EV2400 is getting hot. I recently ordered my kit, can I rise a request to replace a new one?

     Thanks & Regards

    -Himavanth

  • 0 in reply to himavanth reddy
    TI__Mastermind 42535 points

    The MSP on the ev2400 can get slightly hot but not hot enough to burn. Maybe your issue has to do with the circuit change. I will close this thread now, please open another one if you need another ev2400. In that I will find out from sales here what processes need to be followed for verifying a defective unit and replacing it. However, the ev2400 in your case at least seems to be OK except for that it gets hot. Please contact us if you need more help.