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BQ25756: How to enable safety timer on by setting REG ?

sankar eswaran
Intellectual 260 points
Part Number: BQ25756

Tool/software:

Hi,

1. Which Register need to Sets the charging safety timer on the BQ25756 charger controller.
2. How to Reads the adapter present status.
3. How Reads the charger operation status.
4. which Register to Sets the autonomous charging mode.

--->  above 4 functionality how to do which register want to use ?

  • +1
    TI__Mastermind 30915 points

    Hello Sankar,

    Keep in mind you can get most of the information through the BQ25756 datasheet.

    1. This is REG0x15 bits 2:1.
    2. This is in the charger flags register REG0x26. It's bit 7. It will tell you if the input power is in range.
    3. This is REG0x21. It's bits 2:0.
    4. You can set REG0x19[7] REG_RST to reset all the registers to the default values. REG_RST, or register reset, will set all of the registers to the default values. You can also set WATCHDOG=Disable to disable the watchdog timer and the BQ25756 will no longer need communication for the microcontroller to keep the register settings.

    Best Regards,
    Ethan Galloway

  • 0 in reply to Ethan Galloway
    Intellectual 260 points

    My question :

    sankar eswaran said:
    4. which Register to Sets the autonomous charging mode.

    Your answer:

    Ethan Galloway said:
    You can set REG0x19[7] REG_RST to reset all the registers to the default values. REG_RST, or register reset, will set all of the registers to the default values. You can also set WATCHDOG=Disable to disable the watchdog timer and the BQ25756 will no longer need communication for the microcontroller to keep the register settings.

    ---> I am a bit confused. My question was about enabling the autonomous charging mode, but the answer suggests using REG_RST to reset all registers to their default values and disabling the watchdog timer to keep the register settings unchanged. Does setting REG_RST to its default values enable the autonomous charging mode? that's enough Could you please clarify the question?

  • 0 in reply to sankar eswaran
    TI__Mastermind 30915 points

    Hello Sankar,

    The BQ25756 doesn't have designated autonomous charging mode. It just has the register REG_RST that resets the registers to the default values. Once the registers are reset, the BQ25756 will continue to charge based off the programmed resistor values.

    Let me know if you still have questions.

    Best Regards,
    Ethan Galloway

  • 0 in reply to Ethan Galloway
    Intellectual 260 points

    1. the above snipped  i added from BQ25756 Datasheet, what are the Default values if we set REG_RST enable and,

    2.To confirm, does using REG_RST to reset the registers and relying on the resistor values on ILIM_HIZ, ICHG, and FB pins effectively enable what could be considered 'autonomous charging mode' on the BQ25756?

    3. in above picture using this register we can disable watchdog timer and after disable by set 00 values to the register how to we enable watchdog timer again ?

    4. Autonomous Charging mode and Autonomous Charging Cycle both are same if its not same means how to enable that ?

  • +1 in reply to sankar eswaran
    TI__Mastermind 30915 points

    Hello Sankar,

    1. You can check the register map in the datasheet for the default values if EN_RST is enabled.

    2. Yes, that is correct.

    3. You can just set the watchdog timer to work again. Just write 01 or 11 or some other value.

    4. Where do you see these in the datasheet. These should both be the same modes.

    Best Regards,
    Ethan Galloway