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bq24250 - default setting

Other Parts Discussed in Thread: BQ24250

Hi all

Would you mind if we ask bq24250?

Our customer has 4 board with bq24250.

<Condtion>
-When 1st board connected the battery(4.15V) to BAT pin, there is no output at SYS pin(approx 0.3V).
-When 2nd~4th boards connected each batterys(4.15V) to each BAT pin, there are output at SYS pin(approx 4.15V). 
-After 1st board connected VIN to 5V(USB power), SYS pin started to output.
 After then, 1st board removed the 5V(USB power) on VIN, SYS pin keep outputting 4.15V.

About 1st board, there is no supply, so it is not possible to confirm register setting.
We recognize that this situation return to initial(normal) condition by adding the voltage to Vin.

So, as the default setting of bq24250, could you give us the your assumption?
If you need more information(circuit), we will send you using private message.

Kind regards,

Hirotaka Matsumoto

  • Hey Hirotaka,

    Is there any difference between the 1st board and the other 3 boards from a electrical, layout, and/or test condition standpoint (i.e. a different battery, supply, etc).

    My only thoughts right now are that either the Q4 FET in the charger is off, or your pack protectors (if you have any on the battery you are using) are open.
  • Joel san

    Thank you for your reply.

    Is there any difference between the 1st board and the other 3 boards from a electrical, layout, and/or test condition standpoint (i.e. a different battery, supply, etc).
    ->There is a lttle difference, however we think that these conditions are the same.

    My only thoughts right now are that either the Q4 FET in the charger is off, or your pack protectors (if you have any on the battery you are using) are open.
    ->Of course, we could imagine that Q4 FET in the charger is off your pack protectors.
       Actually, we could confirm that pack battery output voltage 4.15V without protection operation.
       As bq24250's default setting, is there the setting wiht Q4 FET off?  Or, why does Q4 FET turn off?

    Kind regards,

    Hirotaka Matsumoto

  • Joel san

    We are sorry to rush you, however could you give us the reply?

    Kind regards,

    Hirotaka Matsumoto

  • Hey again Hirotaka,

    Do you have a load attached to SYS on board 1 that is different from board 2-4 loads?

    Have you tested the same battery on the different boards and still the same issue with board 1 regardless of battery?

    You also said there is a little difference between board 1 and board 2-4. What is this "little difference"?

    The BATFET will also be off if there is a "short circuit" condition, which I believe is around 4A according to the datasheet.


    Regards,
    Joel H