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Question Regarding Connecting bq27742-G1 Fuel Gauge to BQ24040DSQT Battery Charger

Other Parts Discussed in Thread: BQ27742-G1, BQ27532-G1
Hi,

This is my first time using a single cell fuel gauge for my specific project and I'm planning to use the bq27742-G1 fuel gauge. However, I just want to clarify if the Rsense, as shown in the simplified schematic on page 1 of the datasheet, is able to sense negative voltage/current?
That's because I want to clarify how the gauge and the BQ24040DSQT (battery charger), would be connected. I was told that the gauge and the battery cell can be treated as one intelligent battery pack. However, if I were to charge the battery would I connect the Pack+ to the output of the battery charger chip?
Below is an attached block diagram how I perceive how they can be connected.
Inline image 1
Can someone clarify this? 
Regards,
Li-Yen
  • Hi Li-Yen,

    I couldn't see any block diagram attached to your post.  Can you please try posting it again?

    The bq27742-G1 is a "pack-side" gauge which means it is typically used inside the battery pack.  Yes, it can measure negative and positive current through the sense resistor.

    It will be completely independent of the charger, which will be in the "system-side".

    We do offer gauges that can also be put on the same PCB as the charger and processor.  We call these "system-side" or sometimes "host-side"  These are also independent from the charger used, unless you use a Battery Management Unit (BMU) such as bq27532-G1 which can control a charger.

  • Thanks for the quick response. 

    Below is what I thought would work with the charger, where the PACK+ from the fuel gauge would be connected to the OUT pin of the charger as noted above above.

    However, as you mentioned above, does this mean that the fuel gauge I am currently using cannot be used on the same circuit as the charger? Or would the charger just be directly connected to the battery in which the system output, of the OUT pin would be wired with the LDO's within my circuit? 

    Regards,

    Li-Yen

  • Hi,

    I just want to follow up and was wondering if you can see the block diagram that I have attached, and if it's still valid to how I intend to connect the two together?

  • Hi Yang

    You block diagram looks appropriate and valid .

    thanks

    Onyx