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BQ25703A: About register setting method document

Tsukui Yusuke
Guru 21930 points
Part Number: BQ25703A


Hi,

Customers are trying to design BQ25703A software.
Do you have the materials that explain the following steps?

・ Initialize register
・ Setting procedure at the start of charging
・ Setting procedure when charging is stopped
・End processing

The following are the customer's required specifications.
Details are undecided.

Input voltage : 19.5V
Charge voltage : 16.8V
Charge current : 1.25A
Precharge current : 0.25A
Cell : 4

Customers are requesting step-by-step basic information for each register setting procedure.
Could you give me your advice?

Regards,
Yusuke

  • 0
    TI__Mastermind 25800 points

    Hey Yusuke,

    We don't have any material at this moment to start the charger operation, but here are some steps the customer can take.

    1) Trigger on ACOK rising to go and start programming the charging registers for the charger. 

    2) Read the ChargerStatus() status twice register to ensure no faults are present. All faults are latched until cleared and read twice to clear the latch on the flag.

    3) Disable watchdog timer (or make sure it is continually reset). Customer may only want to disable the watchdog for debugging purposes.

    4) Program the MaxChargeVoltage() register. If you select 4S on CELL_BATPRESZ pin, the default will be 16.8V, so this is an optional step.

    5) Program the MinSystemVoltage() register to the lowest voltage you want your system to operate under a dead battery condition. By default, the 4S condition programs the minimum system voltage to 12.288V. Keep in mind that ICHG will be clamped to 384mA when VSRN < VSYSMIN, so you can consider this region part of your pre-charge threshold.

    6) Program the IIN_HOST() register to your input power supply current limit, or other desired current limit.Keep in mind the actual input current limit will be based on the lower of this register setting and the ILIM_HIZ pin voltage setting.

    6a) If you which to disable the external ILIM_HIZ input current limiting function, disable the EN_EXTILIM bit in the ChargeOption2() register.

    7) Program the InputVoltage() register to the desired value. If you do not know the setting to program for step (6), the VINDPM feature will regulate the input voltage in the event the input source is overloaded. This register setting is automatically programmed to VBUS - 1.28V. 

    8) Program the ChargeCurrent() register to the PreCharge or Fast Charge current limit. Keep in mind what I stated in step (5). 

    9) You should continually poll the ChargerStatus() registers to determine if there are any faults while charging. 

    9a) Alternatively, you may use the /PROCHOT features to send an interrupt based on various flags. I will not discuss /PROCHOT here. 

    10) This charge does not terminate charging automatically. You should use a fuel gauge to determine when the battery is fully charged. When you have determined the battery is fully charged, either program the ChargeCurrent() register to 0mA or enable the CHRG_INHIBIT bit in the ChargeOption0() register.

    Regards,

    Joel H