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BQ24040: Unable to drive standalone load

jaydeep Panchal
Intellectual 415 points
Part Number: BQ24040
Other Parts Discussed in Thread: TPS63001, BQ24075

Dear ti support team,

i am using bq24040 for battery changing purpose and tps63001 for generating system supply. 6ma load(MCU and peripherals) is connected to tps63001(which is working excellent with bench power supply), but when i try to connect it with bq24040(OUT pin), tps63001 withdrawing all the pre-charge current. pls help me in troubleshooting.

sch is attached.

thank you,

jaydeep panchal  

  • 0
    TI__Genius 13700 points
    Hello,

    The way that the bq24040 works is that it does monitor where the precharge current is going whether it is to your system or your battery. The only way that you will be able to fix the situation using the bq24040 you are discussing where your system is consuming all of your precharge current is by either reducing system current consumption during precharge or by raising your precharge current.

    The simplest solution would be to use a linear charger that has Power Path Management. One such part is the bq24075. What Power Path does is that it seperatly monitors the current going to the battery so in this particular case if you input source is capable of supplying the 6mA for the system and enough current for the precharge current the charger will take the total needed current and route part of the power to the battery and the other part of the power to the system.

    Let me know if there are any questions.
  • 0 in reply to Ryan May
    Intellectual 415 points

    Dear Ryan May,

    thank you for replying . i have fast charge current of 100 mA and pre charge currunt is set to 20%(20 mA). when tps63001 is running on bench supply its draws 6 mA but when it is connected to bq24040, tps6330 starts making noise and demands more current(100 mA). i don't understand why.

    what's the problem with bq24040's supply?

     

    Regards,

    Jaydeep panchal

  • 0 in reply to jaydeep Panchal
    TI__Genius 13700 points
    Hello,

    Can you share the schematic of what your set up is?

    Also what you supplying in both of these use cases?

    -TPS63001 connected to a bench supply. What is the supply voltage? When you are testing this way are you using the same board and simply replacing the battery with the bench supply?
    -bq24040+TPS63001. What is the supply voltage and current limit of the bench supply connected to the bq24040?

    The fact that the tps63001 is making noise and is demanding a considerable amount of current I want us to focus on this part of the circuit first.

    What does that input and output voltage wave forms of the TPS63001 look like?
    Can you attach a scope capture?
    Also when this 100mA load is happening what what does the /PG pin of the bq24040 look like when you probe it with a scope?
  • 0 in reply to Ryan May
    Intellectual 415 points
    Dear Ryan,

    thank you vary much for reply. i lost layout of tps63001 was bad and that was the issue.

    regards,
    jaydeep panchal