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BQ24800: How to identify the charge overcurrent protection (CHG_OCP)?

Ben Huang1
Intellectual 705 points
Part Number: BQ24800

Hi

 

According to 8.3.8.3, BQ24800 has CHG_OCP built in.

Could you please help to show how to identify this feature?

How to generate the additional current passing through 10m ohm current sensing resistor @ battery charging?

  

Thanks

Regards

Ben

  • 0
    TI__Guru**** 166176 points

    Hi Ben,

    I apologize but our support team for this device is out until January 3rd.  I hope you can wait until then.

    Regards,

    Jeff 

  • 0 in reply to Jeff F
    Intellectual 705 points

    Hi Jeff

    Thanks for your reply!

    It is ok! I can go other items ahead until your support tem on duty!

    Regards

    Ben

  • 0 in reply to Ben Huang1
    TI__Genius 11385 points

    Hi Ben,

    The BQ24800 device has cycle-by-cycle peak overcurrent protection. It monitors the voltage across SRP and SRN, and prevents the current from exceeding the threshold based on the charge current set point. The highside gate drive turns off for the rest of the cycle when over current is detected, and resumes when the next cycle starts. The charge OCP threshold is automatically set to 6, 9, and 12 A on a 10-mΩ current sensing resistor based on charge current register value.

    Thanks,

    Peng

  • 0 in reply to Pengzhao Zhu
    Intellectual 705 points

    Hi Peng

    Thanks for your description!

    Could you please help to reproduce the waveform with a brief description and show how you generate the current other than the setting of REG0x14() @ battery charging?

    We cannot complete the electrical validation without your support!

    Regards

    Ben

  • 0 in reply to Ben Huang1
    TI__Mastermind 33035 points

    Hi Ben,

    This is an IC level test parameter which is hard to test on a EVM board. 

    Regards,

    Tiger

  • 0 in reply to Tiger Zhou
    Intellectual 705 points

    Hi Tiger

     

    As mentioned, it is an lC level test parameter; does it mean that it is gained by the open loop test?

    Once I consider the BQ24800 as a generic buck converter and pulling the current with constant-current load @ VBAT instead of connecting a battery, as a result, the REG0x14() seems to be treated as the level of overcurrent

    Please refer to the captured waveform as follows

     

     0x14() = 0800 = 2048mA

     0x15() = 2800 = 10240mV

    CH1: VBAT: CH2: HIDRV: CH3: LODRV; CH4: IBAT

    IBAT = 2A Continuous (CC Load)

    CH1: VBAT: CH2: HIDRV: CH3: LODRV; CH4: IBAT

    IBAT = 2A to 2.1A

    CH1: VBAT: CH2: HIDRV: CH3: LODRV; CH4: IBAT

    IBAT = 2A to 2.1A

     

    Whether I can conclude this behavior is over current protection or not?

    Should I check something else to make sure?

     

    Thanks for your suggestion and comment!

     

    Regards

    Ben

  • +1 in reply to Ben Huang1
    TI__Mastermind 33035 points

    Thanks Ben for the detailed waveforms. 

    I don't think this is CHG_OCP, you are far away from 6A CHG_OCP level. 

    This part is designed to work with a battery. The behavior may be different if pairing with an active load. It is not recommended to use as a generic dcdc converter. 

    Regards,

    Tiger