• State Resolved
  • Locked Locked
  • Replies 5 replies
  • Answers 2 answers
  • Subscribers 63 subscribers
  • Views 85 views
  • Users 0 members are here
Support feedback
Options
Options
Related

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

BQ25751: If we can use the battery charge enable function to finish the battery absent detection

sun qiyun
Intellectual 280 points
Part Number: BQ25751
Other Parts Discussed in Thread: BQ25750,

Tool/software:

Dear

In my design, I want to judge if the battery is absent or not by monitoring the battery voltage.

The battery power input would be the same point as the battery charger power output.

When I detect the battery voltage, I will enable the battery charger firstly, I think this point voltage is the external battery voltage. 

Is it right? Is this method feasible?

Hope I can get your reply soon.

Thanks!

  • 0
    TI__Mastermind 32236 points

    Hello Sun,

    The BQ25751 can't detect when a battery is present in hardware. There is a workaround for detecting a battery is present with I2C. When charge is enabled and a battery is not present, the BQ25750 will charge the battery, reach termination very quickly, the voltage will fall to the recharge threshold and the battery will start charging again. While this happens, CHARGE_FLAG will be set every time the oscillation will happens and the CHARGE_FLAG will be reset after it is read. So to detect if a battery is present, you can read the CHARGE_FLAG once every second for 3 times to detect if a battery is present at startup.

    Best Regards,

    Christian.

  • 0 in reply to Christian Moyer
    Intellectual 280 points

    Hi，Christian

    I will not use BQ25751 to detect battery is absent or not.

    I want to detect the battery voltage. But when the battery charger is enabled, the point voltage would not be battery actual voltage, is it right? Maybe I misunderstand?

    So I want to disable the battery charger before detecting the battery voltage. But I cannot be sure it is feasible. Could you please help check this method? 

    And one more question is when the battery is absent, the FB voltage will be what?

    Thanks! 

  • 0 in reply to sun qiyun
    TI__Mastermind 32236 points

    Hello Sun,

    sun qiyun said:
    I want to detect the battery voltage. But when the battery charger is enabled, the point voltage would not be battery actual voltage, is it right? Maybe I misunderstand?

    Where are you measuring? if you our measureing at VOUT, then it should be the actual battery voltage while charging and while not charging.

    sun qiyun said:
    And one more question is when the battery is absent, the FB voltage will be what?

    This shoulld be 0V

  • 0 in reply to Christian Moyer
    Intellectual 280 points

    Hi, Christian

    Christian Moyer said:
    Where are you measuring? if you our measureing at VOUT, then it should be the actual battery voltage while charging and while not charging.

    Below point circled red is the test point. Yes, it is the VOUT. I want to test this point voltage to judge if the battery is absent  or not. According to your explain, I think I could not disable the battery charger before measuring this point voltage, right? This point voltage always battery voltage.

    Thanks!

  • +1 in reply to sun qiyun
    TI__Mastermind 32236 points

    Hello Sun,

    sun qiyun said:
    Below point circled red is the test point. Yes, it is the VOUT. I want to test this point voltage to judge if the battery is absent  or not. According to your explain, I think I could not disable the battery charger before measuring this point voltage, right? This point voltage always battery voltage.

    Yes, That should be correct.

    Best Regards,

    Christian.