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BQ25756: BQ25756

Shony Sinay
Prodigy 20 points
Part Number: BQ25756
Other Parts Discussed in Thread: BQ25750

Hi all,

The BQ25756 datasheet says that the user can control the charging current limit. But the current sensing resistor Rbat,sns In all the design examples is located between the external input switching resistors and the SYSTEM output port. The battery is connected between the SYSTEM port and GND (see picture below).

Means that the sense resistor measures actually not only the charging current but actually the System+BatteryCharging current.

My question is:

Is it possible to move the resistor between the SYSTEM port and the battery (according with the SRP and SRN connections) in a way that the chip will measure only the battery charging current?

Note that I am not going to use the back drive USB option. 

Thanks.

  • 0
    TI__Genius 16020 points

    Hello Shoney,

    Thanks for working with us.

    For the BQ25756, it is not possible to separate battery charging and load currents. You could raise the charging current to meet both the system load and the battery charging current. Will this work for you?

    Have you looked into the BQ25750? This is a traditional power path battery charge controller. System and battery are separated with this charger.

    What is a back drive USB option?

    Best Regards,
    Ethan Galloway

  • 0 in reply to Ethan Galloway
    Prodigy 20 points

    Thank you Ethan,

    After rereading the datasheet I found out that this configuration can be actually beneficial in that it allows automatic and dynamic control of the charging current level dependent to the system current level. So, I now consider to use it.

    Regarding the USB option - I don't use it.

    About the BQ25750 - It looks interesting too. I will check it.

    B.R