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Original question:

BQ25672: bq25672

BQ25672: bq25672

syam kandelli
Prodigy 180 points
Part Number: BQ25672

Tool/software:

Hi jeff,
 the BQ25672 charger IC, which has overvoltage protection up to 26V. I tested this and when the input voltage exceeds 26V, the IC correctly cuts off the input. However, when the input voltage is reduced back to a normal level, the IC does not automatically resume operation. It only starts working again if I unplug and reconnect the input source.
Is there any method, either through software or hardware, to restore normal operation without requiring a power cycle?


Regards 
syam

  • 0
    TI__Guru**** 166626 points

    Hi Syam,

    How far below 26V did you take VBUS?  There is some hysteresis? Can you provide REG0x0F and REG0x1B through REG0x27 after this occurs?

    Regards,

    Jeff

  • 0 in reply to Jeff F
    Prodigy 180 points

    Hi jeff,
    I increased it to 27v
    Regards,
    syam

  • 0 in reply to syam kandelli
    TI__Guru**** 166626 points

    Hi Syam,

    When I do this on the bench, I see charge auto restarting when VBUS drops below 25V.  Can you provide REG0x0F and REG0x1B through REG0x27 after this occurs?

    Regards,

    Jeff

  • 0 in reply to Jeff F
    Prodigy 180 points

    Hi jeff
     

    These signals are from my custom BQ25672 charger board. I haven't connected any battery or load. In a 2-cell configuration, I am getting these signals.


    After adding a 100µF capacitor, vsys I am getting these signals.

    I captured these signals from the EVM board. The signals from my board and the EVM board are

     also added 100uf in vsys on the evm board.


    These signals are slightly different between my board and the EVM board. Both are in a 2-cell configuration.

    Regards
    syam



  • 0 in reply to syam kandelli
    TI__Guru**** 166626 points

    Hi Syam,

    With no battery attached and charge enabled (not disabled using /CE pin, CE bit or TS fault), those waveforms are expected.  To prevent, you need add 200uF on BAT not SYS.  

    Regards,

    Jeff

  • 0 in reply to Jeff F
    Prodigy 180 points

    Hi Jeff,
    I am working with the BQ25672 charger EVM board and a custom board. I want to perform a load test ranging from 10mA to 5A.

    Can you guide me on how to conduct these tests with and without a battery? Additionally, I need to perform more tests by applying different input voltages.

    Could you provide a test report or test cases for all test scenarios?

    Also, can I test a 1mA load? Does this circuit support such a low current load?

    Regards 
    Syam

  • 0 in reply to syam kandelli
    TI__Guru**** 166626 points

    Hi Syam,

    I do not have a report like that.  The best "report" of data that we have taken is the efficiency data in the datasheet.  The charge current through the internal batFET to the battery is the same as a load on SYS. There is no minimum load requirement so 1mA is okay.  At light load, the converter is default configured to operate in PFM mode for highest efficiency.  This means that V(SYS) can be as high as 600mV above VREG.   I recommend testing:

    VBUS=VREG, VREG+0.5V, VREG+1V, etc. up to your max VREG

    ISYS = 1mA, 10mA, 50mA 100mA, 300mA, 500mA, 700mA, 1A, 1.5A, 2A, 2.5A, 3A, 3.5A, 4A, 4.5A, 5A

    The IC package gets quite hot and likely will not be able to provide 5A as it will enter thermal regulation and limit its input power.

    Regards,

    Jeff

  • 0 in reply to Jeff F
    Prodigy 180 points

    Hi jeff,
    I have set Vbus to 5V and 3A on the bench power supply. I am testing from 10mA by connecting a test load to Vbus. However, after 500mA, it is not showing a reading. The Vbus side has a constant voltage with no drops. The power supply is not displaying the current, and when I check with USBAny, it also does not show the current.after 600mA, the Vsys voltage drops completely to 0V. On the EVM board, I have set ILIM-HIZ to 1.5A.

  • 0 in reply to syam kandelli
    Prodigy 180 points

    Hi jeff,

    Please let me know the correct output current setting for 3A on the EVM board.

    Regards
    Syam

  • 0 in reply to syam kandelli
    TI__Guru**** 166626 points

    Syam,

    I recommend tying ILIM_HIZ = REGN to set the highest IINDPM or use the ChargerGUI to disable ILIM_HIZ pin by setting EN_ILIM=0 and then changing IINDPM to 3A.  Then, I recommend measuring the VBUS pin voltage using testpoint TP23 to GND to confirm that there is neglible voltage drop due to resistive cables from power supply to EVM board.  If there is a drop, increase the voltage from the supply.  If you do not have a battery or battery simulator attached, I recommend disabling charge by either removing the shunt on JP17 or setting EN_CHG = 0 in the GUI.

    Regards,

    Jeff