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BQ24075: What's the cut off voltage of Battery.

David Kim2
Expert 2600 points
Part Number: BQ24075

Hi

I have the question as below.

-CONDITION-

Don't connect the Adapter, only operation with battery.

Connecting the Vout pin to the System.

-Question-

1. What is the lowest voltage on the battery that shuts down the output?

2. Is the charging current 1.5a the input current 1.5a? Or is it possible to charge the battery up to 1.5a?

Thanks

  • 0
    TI__Mastermind 23200 points

    Hi David,

    David Kim2 said:
    What is the lowest voltage on the battery that shuts down the output?

    The BQ24075 does not have a battery under voltage lock out feature and so it will power VOUT until VOUT hits 250 mV. 

    David Kim2 said:
    Is the charging current 1.5a the input current 1.5a? Or is it possible to charge the battery up to 1.5a?

    Both the charge current and the input current limit can be set to 1.5 A. 

    Let me know if there are any additional questions.

    Best Regards,

    Anthony Pham

  • 0 in reply to Anthony P Pham
    Genius 5240 points

    Hi, Anthony

    I have additional questions.

    [System description]

    1. Battery capacity: 510mAh

    2. Output : 3~3.5A, PWM(500hz) duty control

    Issue: In low battery (3.7~3.8V), Vout drops more than 200mV than Vbatt, the output is cut off, output disconnection proceeds, and turns on after about

    50msec.

    (Yellow : output voltage, Green : Battery voltage)

    Q : Is there a way to prevent the output from being cut off by changing the settings of the IC even in a short circuit situation?

    Thanks.

    Regards,

    MJ

  • 0 in reply to MJ Jeon
    TI__Mastermind 23200 points

    Hi MJ,

    You're correct that this is the short circuit detection threshold. 

    No, there is no way to change the short circuit detection threshold. 

    Best Regards,

    Anthony Pham

  • 0 in reply to Anthony P Pham
    Genius 5240 points

    Hi, Anthony

    Thank you for kindly answer.

    Does short circuit detection work only by the relationship between Vbat and Vout?

    Assuming, is the short circuit protection caused by the symptom of Vout dropping due to an excessive load on the output?

    If this is the cause, the output load is max. Are there any products that do not operate short circuit protection (can withstand higher output loads) even at

    3.5~4A?

    Or is there a product without short circuit protection?

    If there is a product without short circuit protection, won't it damage the parts if the product exceeds 3.5A output load? Or maybe there are other side effects?

    After comprehensively reviewing these parts, if there is a suitable product, please recommend it.

    Thanks.

    Regards,

    MJ

  • 0 in reply to MJ Jeon
    TI__Mastermind 23200 points

    Hi MJ,

    Short circuit protection is VOUT dropping due to an excessive load. As this is a battery power case the VOUT needed to stay within about 250 mV of VBAT to prevent the short circuit fault. I'll need to take a look and see as a higher amperage current would be a switching charger. Can you provide the following information so we can take a look?

    Charge Current: 

    Battery Regulation Voltage:

    Characteristic of high output load: Frequency, Duty Cycle, peak current:

    Best Regards,

    Anthony Pham