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BQ24055 - not charging LIR1620H battery

Sam Frey
Prodigy 10 points
Other Parts Discussed in Thread: BQ25120, BQ25100, CC2564

My circuit is basically like the reference design for BQ24055 shown in fig 28 of datasheet, the battery I have attached is an LIR1620H, 3.6 V, 20mAh capacity.

Vout looks like it's in a constant "battery detect cycle", the CHG LED never turns on regardless of this battery voltage level.

Thanks for the help.

  • 0
    TI__Mastermind 20570 points
    Please use the schematic in the user guide as the reference design.
    The example of datasheet page 28 sets the fast charge current to 540 mA. Your battery is a 20mAh battery. This will trigger the overcurrent protection on the battery if the battery has an internal protection circuitry. Please verify with your battery spec to set the proper charge current.
  • 0 in reply to Jing Zou
    Prodigy 30 points
    We found the charge current for the battery is 4mA. We used a R_ISET=26K based on 20mA battery. The circuit is not working and we can't figure out what is wrong. We pulled TS off (open). Rpre-term is set to 2K.
  • 0 in reply to Sergio Cardona
    TI__Mastermind 20570 points

    If the charge current for the battery is 4mA, then setting the charger to 20mA can still trigger the over current protection. I suggest you to use bq25100 or bq25120 for such small battery. The evaluation board can be ordered from our website. 

  • 0 in reply to Jing Zou
    Prodigy 30 points
    Actually, we would need to set the current to 40mA or higher due to the BLE (CC2564). I am trying not to change the design if I could since we are in the final stages of the development.
  • 0 in reply to Sergio Cardona
    TI__Mastermind 20570 points

    Please share your schematic of the system and block diagram on the connection of the cc2564.  ISET is used to program the fast charge current which should only be depending on your battery spec regardless of your system load connect to the battery. You can set the input current limit which can be set by ISET2.

    I_IN = I_BAT+I_LOAD