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BQ25622E: The application issues of chips

Tonyx.wu
Genius 3985 points
Part Number: BQ25622E

Tool/software:

1) The charging current of BQ25622E is almost zero, but it won't stop charging.  The software reads it as being in CV mode.  What could be the reason for this?



I set the charging voltage to 4.3V here and set the battery voltage to 4.3V



Then, when reading the charging status register, it was found that it was still in the CV stage



Then, a distinct noise can also be heard, which should be caused by the inductor.  Once the charging stops here, there won't be any noise

2）Please check the schematic diagram and LAYOUT to see if there are any issues. If there are, please provide detailed suggestions for modification

This is a PCB.  Due to some issues, a line flew out, which is marked in the picture

  • 0
    TI__Mastermind 31740 points

    Hello, 

    Please see my comments below. 

    1) What is the termination current threshold, set in REG0x12 in your testing? If you leave the test running for an extended period of time does termination never occur? 

    Tonyx.wu said:
    Then, a distinct noise can also be heard, which should be caused by the inductor.  Once the charging stops here, there won't be any noise

    What is the total current draw between both SYS and bat at the time noise is heard? It is possible current draw is low enough that switching in the audio range is occurring. 

    2) 

    On schematic review I have the following comments:

    -TI recommends using at minimum a 10V rated capacitor at REGN. Your current capacitor is below this minimum recommended voltage rating. 

    -Digital open drain outputs such as /PG, STAT, and INT pins require connection to a pullup rail via a resistor such as 10kohm to function as intended. 

    -I see schematic denotes input current as 3A, but ILIM pin resistor of 5.1kohms will set input current limit to approximately 490mA. 

    Besides these comments the rest of the schematic is okay. 

    On Review of the layout I do not see any major concerns. One comment is you will want to minimize parasitics on the path from BTST pin to the BTST capacitor, which is placed near the inductor.  You ideally want this to be a wide enough trace to not have a negative impact on performance. 

    Best Regards,

    Garrett 

  • 0 in reply to Garrett Kreger
    Genius 3985 points

    What configuration on the BQ25622e software would cause the output voltage of sys to become 0V when it is trickle charging?

  • 0 in reply to Tonyx.wu
    TI__Guru** 105760 points

    Hello,

    There's no specific setting that would cause SYS to fall during CV, we have system reset features which allow the BATFET to be disabled briefly when QON or I2C command is asserted.

    The section in the datasheet is: 8.3.8 BATFET Control.

    Sincerely,

    Wyatt Keller