System for sensing current through a pass FET

An electronic circuit for sensing a current through a pass Field-Effect Transistor (FET), comprising:

• a first sense circuit configured to pass a first sense current (I_sense1) should there be a difference between a supply voltage (Vcc) and a source voltage (Vout) of the pass FET that is small;
• a second sense circuit configured to pass a second sense current (I_sense2) should the difference between the supply voltage (Vcc) and the source voltage (Vout) of the pass FET be large;
• wherein the first sense circuit comprises a first sense FET, a first sense amplifier, and a first switch that is configured to turn off when the difference between the supply voltage and the source voltage of the pass FET is large and turn on when the difference between the supply voltage and the source voltage of the pass FET is small;
• wherein one leg of the first sense FET is connected to the supply voltage (Vcc), wherein another one leg of the first sense FET is connected to a negative input of the first sense amplifier and to one leg of the first switch;
• wherein the first sense FET has a gate that is connected to a charge pump, wherein the first sense amplifier has a positive input that is connected to the source voltage (Vout);
• and
• wherein the first sense amplifier has an output that is connected to a gate of the switch for switching the first switch and enabling the first sense current to flow when the first switch is switched on;
• wherein the second sense circuit comprises a second switch that is configured to turn off when the difference between the supply voltage and the source voltage of the pass FET is small and turn on when the difference between the supply voltage and the source voltage of the pass FET is large;
• and
• wherein the first sense current and the second sense current are representative of the current through the pass FET.