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BQ24773 shut down issue

Patrick Chen
Mastermind 8875 points
Other Parts Discussed in Thread: BQ24773

Hello,

           while AC adapter connect to system always, customer hot swap the battery then happen system shutdown suddenly issue. VBATA-X will be drop then affect VBATA to cause system work abnormal. Do you have any suggestion to solve this issue? Thank you. 

           

 Schematics

https://drive.google.com/file/d/0B4htKR16pRs8cWhxbjJxVzI2TmM/view?usp=sharing          

BR

Patrick     

  • 0
    TI__Guru 56650 points
    What test conditon difference is between the first picture and the second picture? Do they both have the same issue?

    bq24773 has /BATPRES pin. When BATPRES pin goes from LOW to HIGH, the device exits LEARN mode, and disable charge. REG 0x15() value
    goes back to default. So, when customer hot swaps the battery, does the BATPRES pin go from LOW to High? If they can make BATPRES pin from LOW to HIGH at battery hot swap, they can avoid the issue.

    Or, please try to add more system capacitance to avoid this issue.
  • 0 in reply to Wang5577
    Mastermind 8875 points
    Hello,

    Could I know how to know the battery is present or removal operation by BATPRES pin? Is it need to connect to battery with BATPRES pin or it is use SRP/SRN to sense and monitor the battery is present or not. Thank you.

    BR
    Patrick
  • 0 in reply to Patrick Chen
    TI__Guru 56650 points

    /BATPRES: Active low battery present input signal. LOW indicates battery present, HIGH indicates battery absent. When /BATPRES pin goes from LOW to HIGH, the device exits LEARN mode, and disable charge.

    Some battery pack has internal pull-down resistor on one of its output terminal pins. In this case, the charger side only needs a pull up resistor to pull BATPRES high and connects /BATPRES to battery pack terminal. When the battery pack is plugged in, the /BATPRES is pulled down.

    If the battery pack doesn't hase internal pull-down resistor for /BATPRES and customer wants to use this /BATPRES function, they can monitor the battery votlage and control the /BATPRES pin.