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BQ25895M: Powering load via SYS pin? Whats the max current? what section of datasheet is relevant?

Senthil Seveelavanan
Prodigy 80 points
Part Number: BQ25895M

Hi,

Hi, I want to power a low power MCU off the SYS pin. Is this permitted?

Cheers

  • 0
    TI__Guru**** 165986 points

    Senthil,

    The SYS pin draws power from VBUS through the buck converter.  If the input source is too weak or you have limited the charger's input current (IINLIM), then the battery FET between BAT and SYS turns on and the battery supplements the SYS load current.  You can estimate the maximum load current using the efficiency power balance equation:

    eff = (Po/Pi) = (VSYS*(ISYS+ICHRG))/(VBUSmin*IINLIM).  Datasheet figure 1 shows charger efficiency.

    Powering a low power MCU should not be a problem a high enough rated adapter and battery.