I am building a Battery Management System (BMS) using the bq769 family IC from Texas Instruments. For my application, the PACK- serves as the ground reference, so I am trying to figure out how the RSNS can be used to measure the current, once its terminals will have the same voltage level when the MOSFET is open.

 

Welcome to AAC.

Your question is confusing. If the MOSFET is open there will be no current to measure. When it is closed \(\mathsf{R_{SNS}}\) will act as a burden resistor, as expected.

Can you clarify where your confusion lies, or what I am missing?