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BQ25886: BQ25886 Charging problem

David chen
Expert 1200 points
Part Number: BQ25886

hi  Team:

1.   If only D+.D- is connected together and not connected to the D+,D- of USB, is the input current limited to 3A?

2. I have connected  D+,D-with USB  D+,D-,The schematic diagram is shown below! USE 5V  to  2S bat  charge!

When BQ25886 first input, 5V power supply , then  inserted the battery . The charging current is 950mA.

When first  inserted the battery  then the 5V power is added to the BQ25886, and the charging current is 640mA?

Why are there different charging currents?

  • 0
    TI__Genius 10385 points

    David,

    1. If D+/D- are connected together the input current limit would be set to 3.0A assuming a lower charge current limit is not set by ILIM or the ICO routine. In your customer's schematic I see the current limit is set to ~1.98A by the ILIM pin. On this schematic, ILIM would set the current limit. 

    2. The charge current limit is set by ICHGSET. I see the customer schematic shows that the current limit would be ~630 mA. I am confused as to why the charge current would increase beyond the set limit.

    Could you please set an oscilloscope capture showing VBUS,VBAT, VICHGSET, and ICHG during both start up sequences? This would help me understand what is happening.

    Thanks,

    Ricardo

  • 0 in reply to Ricardo
    TI__Genius 10385 points

    David,

     

    I have not heard back from you in a while. Please let us know if you have any further questions, otherwise I will be closing this thread.

     

    Thanks,

    Ricardo