Integrated MOSFET current sensing for fuel-gauging

摘要

Integrated MOSFET current sensing for fuel-gauging. A 1st MOSFET through which the current is to be sensed is coupled to a 2nd MOSFET of the same type, the 2nd MOSFET being biased to have the same resistance as the 1st MOSFET. The 2nd MOSFET has a much smaller area than the 1st MOSFET, and is coupled to a current source representing a maximum current through the 1st MOSFET. The voltage across the 1st MOSFET relative to the voltage across the 2nd MOSFET provides a measure of the current through the 1st MOSFET. Various embodiments are disclosed, including embodiments in battery packs to eliminate the need for additional and expensive external components.