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BQ25713: bq25713 in VINDPM during forward mode

GARETH OU
Guru 11655 points
Part Number: BQ25713
Other Parts Discussed in Thread: BQSTUDIO

Hi

The customer has a TI BQ25713 charger used in a project. During actual debugging, it is found that the charger will enter "in VINDPM during forward mode". Details are as follows There are 3 strings of batteries. The adapter is a 20V, 3.25A, 65W type-c adapter. When AC+DC, the charger part is set as ChargeOption0 = 0x670E ChargeCurrent = 0x0500 (1280mA) MaxChargeVoltage = 0x3320 (13.088mV) MinSystemVoltage= 0x2400 (9216mV) InputVoltage = 0x36C0 (14016mV) IIN_HOST = 0x4200 (3300mA) The system is idle and only charges the battery. When the battery capacity reaches 80%, turn off charging by setting "CHRG_INHIBIT" of ChargeOption0. At this time, read the "ChargerStatus" register and find that bit4 is 1. That is, the charger has entered VINDPM mode. Recording the battery information, I found that the charger automatically starts charging, and the charging current is higher than the set 1.28A, and the charger will charge for a period of time and then turn off for a period of time, and this cycle lasted for about 30 minutes. As shown below

The sign = indicates that the charger has been set to stop charging, but the current data is still there and the battery voltage is also increased due to the charger being turned on. PS, 100% means the battery capacity is 100, the actual battery capacity is 80% at this time, but it is reported as 100% and the charging is stopped. The system is completely idle, only charging, and the AC is always plugged in, VINDPM is set to 14V, why does the charger enter "VINDPM during forward mode", check the spec of BQ25713, and find no useful information. To correct it, the bit3 of the chargerstatus register is 1. That is, it has entered the "IINDMP" mode add some information BQ25713 "ChargeSts" register value is 0x8800. The charging current has been set to 0, and the charge Inhabit bit is also 1. But looking at the battery information, it can be turned on until the charger is turned on for about 4s, and turned off for 4s, and the maximum charging current is close to 4A.

  • 0
    TI__Mastermind 34775 points

    Hi Gareth,

    The charger has two outputs: One is the system rail, the other is the battery rail. It is possible to run into VINDPM in forward mode. I would suggest you isolating the output and monitor each output voltage and current.  You can also use BQStudio to read all the register information. 

    Regards,

    Tiger

  • 0 in reply to Tiger Zhou
    Guru 11655 points

    Hi Tiger

    Thank you for your reply.

    1.When charging, it is normal. But when the charging of the charger is turned off, it will report IINDPM. The customer reads part of the registers of the charger and confirms that the charger_inhit is 1 and the charging current is 0. The charger status register value is "0x8800" The strange thing is that in this mode, according to the instantaneous current of the battery, it can be seen that the charger is frequently switched on and off to charge, and the charging current is as high as 3A or more. Is this behavior as expected? Apart from increasing the Input current limit, is there any other way to avoid entering this mode? In addition: if you try to turn off Peak Power Mode, the charger will report "ACOC". The customer's hardware ILIMIT is 3A, and the software ILIMIT1 is 3.4A. When the hardware ILIMIT is turned off, the phenomenon remains the same.

    2.I checked the spec, and did not find a detailed description of IINDPM. What does this refer to? How to trigger and enter this mode?

  • 0 in reply to GARETH OU
    TI__Mastermind 32355 points

    Hello Gareth,

    Tiger is out of the office for the day. He will be back tomorrow.

    Best Regards,
    Ethan Galloway

  • 0 in reply to Ethan Galloway
    TI__Mastermind 34775 points

    Hi Gareth,

    For the input current dynamic power management, please watch our training video at 7:30 time mark. 

    https://www.ti.com/video/series/battery-management-deep-dive-on-demand-technical-training.html

    Could you provide the register dump for us to review? Also schematic?

    Regards,

    Tiger

  • 0 in reply to Tiger Zhou
    Guru 11655 points

    Hi Tiger

    The value of the register is as follows

    I read the above registers through IIC to confirm that the write is successful.

    schematic as below

    Since the project uses 3 strings of batteries by default, the voltage of "CELL_BATPRES" in the above figure has been revised to 3.85V, that is, 3cell batteries. Thanks.

  • 0 in reply to GARETH OU
    TI__Mastermind 34775 points

    Hi Gareth,

    A few observations: 

    1. Set the input voltage to 0x00, thus will effectively disable VINDPM.

    2. Disable watchdog timer for debugging.

    3. Remove C316 input cap. The input capacitance after RAC is 10nF+1nF. 

    Try to see if any improvement. 

    Regards,

    Tiger