Method and apparatus for sensing current in a back-to-back configuration

An apparatus for sensing current in a back-to-back MOSFET configuration, the apparatus comprising:

• a first MOSFET having a gate terminal, a drain terminal, and a source terminal;
• a second MOSFET having a source terminal coupled to the source terminal of the first MOSFET, a gate terminal, and a drain terminal;
• a gate driver circuit including at least one gate drive output terminal to output a gate drive signal to the gate terminals of the first and second MOSFETs, and a return terminal coupled to the source terminals of the first and second MOSFETs;
• a shunt resistor coupled between the source terminals of the first and second MOSFETs;
• and
• a second MOSFET return resistor coupled between the source terminal of the second MOSFET and the return terminal of the gate driver circuit;
• wherein a resistance of the second MOSFET return resistor is greater than a resistance of the shunt resistor and
• wherein the drain terminal of the first MOSFET is to be coupled to a voltage source, and the drain terminal of the second MOSFET is to be coupled to a load.

A method of sensing current in a back-to-back MOSFET configuration, the method comprising:

• generating, by a gate driver circuit, a gate drive signal to drive a gate terminal of a first MOSFET and a gate terminal of a second MOSFET;
• forming a gate drive signal return path from a source terminal of the second MOSFET through a shunt resistor coupled between the source terminal of the second MOSFET to a return terminal of the gate driver circuit based on a resistance between the source terminal of the second MOSFET and the return terminal of the gate driver circuit that is greater than a resistance of the shunt resistor;
• and
• detecting a voltage drop across the shunt resistor so as to detect current through the shunt resistor.