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BQ40Z50-R1: FUSE ISSUE

Bang Duong
Prodigy 100 points
Part Number: BQ40Z50-R1
Other Parts Discussed in Thread: BQ40Z50, BQ24610

Tool/software:

We using BQ40Z50-R1, after the PCBA mass production test has passed,  we connect the PCBA to the battery. The golding cycle is OK, and then we put it away.

Several days later, when we tested again, we found some problems—a few BMS with no output voltage. We checked and found that operation status FUSE bit has been set to 1 for no reason in SBS, resulting in CHG and DSG MOS turning off. CHG and DSG bit is set to 0. 

The schematic is as follows.


Please check it and help me to solve this problem.

  • 0
    TI__Mastermind 28450 points

    Hello,

    If possible, can you please send the .gg file of the gauge settings, along with a log file depicting the FUSE bit becoming set? This would allow us to take a deeper look into what is occurring within the gauge.

    Regards,

    Anthony Baldino

  • 0 in reply to Anthony
    Prodigy 100 points

    Hi,

    I have PCBA boards, which can charge and discharge the batteries normally. After a while, I found a circuit that could not charge or discharge the battery. I rechecked and compared the register values ​​of the 3 circuits and found they were the same. FUSE = 0, FET_EN = 0, registers DSG = 1, CHG = 1 however when I measured the 2 FETs were still not open. 

    When I measure the VGS voltage at 2 MOSFETs, the measured voltage is only 0.4V, the MOSFET cannot open.

    Can I keep the gauging function without using two MOSFETs? I will connect the battery directly to the discharge charger.

    Thanks,

    Bang Duong

  • 0 in reply to Bang Duong
    TI__Mastermind 28450 points

    Hi Bang,

    Bang Duong said:
    I have PCBA boards, which can charge and discharge the batteries normally. After a while, I found a circuit that could not charge or discharge the battery. I rechecked and compared the register values ​​of the 3 circuits and found they were the same. FUSE = 0, FET_EN = 0, registers DSG = 1, CHG = 1 however when I measured the 2 FETs were still not open. 

    If possible, can you please confirm whether the [XCHG] or [XDSG] bits are becoming set at this time?

    Also, can you please let us know what the values of the SafetyStatus() and PFStatus() are?

    What voltage are the cells individually being charged to?

    Bang Duong said:

    When I measure the VGS voltage at 2 MOSFETs, the measured voltage is only 0.4V, the MOSFET cannot open.

    Can I keep the gauging function without using two MOSFETs? I will connect the battery directly to the discharge charger.

    The gauging can be completed without the two FETs on CHG and DSG, which are there for protection purposes. If these are removed, please ensure that the integrated protections of the bq40z50 device are set correctly.

    Regards,

    Anthony Baldino

  • +1 in reply to Anthony
    Prodigy 100 points

    Hi Anthony,

    1. Also, can you please let us know what the values of the SafetyStatus() and PFStatus() are?

    => The SafetyStatus() and PFStatus() values are 0, which means IC runs normally. [XCHG] or [XDSG] bits values are 0.

    2. The voltage when I start charged total is 12.2V, which means about 4V/Cell, Battery Li-ion 3S

    3. I use BQ24610 for a charger when I connect the battery without BQ40Z50, The Battery can charge and discharge normally. So I still know why two MOSFETs can not open normally, and I think two MOSFETs can be removed and connected directly to the battery with BQ24610, and I am still gauging the battery.

    4. Also, when I disconnect the battery from the bq40z50 and then reconnect the battery, the IC becomes sealed, and then I have to reactivate the IC. Can you tell me how to prevent the IC from returning to this sealed state?

    Thanks,

  • +1 in reply to Bang Duong
    TI__Mastermind 28450 points

    Hi Bang,

    Thank you for the clarifications for my questions.

    If possible, can we receive the .gg file of the gauge settings so we may look into them? Also, if you happen to have a log file of the [FUSE] bit becoming set that would help us.

    Bang Duong said:
    4. Also, when I disconnect the battery from the bq40z50 and then reconnect the battery, the IC becomes sealed, and then I have to reactivate the IC. Can you tell me how to prevent the IC from returning to this sealed state?

    If the gauge is in a sealed state when the golden image is pulled, then the gauge will return to a sealed state every time there is a power cycle. I believe this can be avoided if an .srec is pulled with the gauge in an unsealed state then reprogrammed to it.

    Regards,

    Anthony Baldino

  • 0 in reply to Anthony
    Prodigy 100 points

    Hi Anthony,

    When I use battery 3S, If I replace c33 and c40 with 0-ohm resistors, will it affect the battery balancing results?

    Thanks,

  • +1 in reply to Bang Duong
    TI__Mastermind 37761 points

    Hello Bang,

    Anthony will be out of town for a while but can continue to support you.

    C33 and C40 are unnecessary in the design. Those can be removed. VC4 and VC3 can be directly shorted together, as well as V4 and V3.

    R41 and R52 can also be removed.

    Regards,

    Nick Richards

  • 0 in reply to Adrian
    Prodigy 100 points

    Hi Nick,

    Thank you very much.

  • 0 in reply to Bang Duong
    TI__Mastermind 37761 points

    Your welcome!

    Nick Richards