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BQ24090: battery is charged just 3.5 v why?

navidrct ansari
Expert 1975 points
Part Number: BQ24090
Other Parts Discussed in Thread: BQ24092

i have bq24092 with this schematic 

when i connect battery to it , it charge just 3.5Volt and allot sooner CHG goes high 

what is the problem?what u suggest to put on ISET and Iset2 and Preterm?

  • 0
    TI__Guru 68996 points

    Hello

    Check the input current during charge and compair it with your target charge current.  Input current will be almost the same as charge current.  With battery voltage between 2.5V and 4.1V device will be in fast charge and current will be set by ISET and ISET2.

    ISET of 590 ohms will be about 915mA

    But ISET2 high will limit input current to 500mA, may want to consider grounding ISET2.

    Preterm is set to 2% this is a little low, recommend 10% or 2k ohms.  

    Check input voltage to make sure it is not dropping during charging--will reduce charging current.

    Also check thermal rise of the device--also reduce charging current.