Current sensor with extended voltage range

A method of sensing current, the method comprising:

• providing an output current to a load with an output transistor of a first type, the output transistor having a first current path terminal coupled to a first supply terminal, and a second current path terminal coupled to the load;
• copying the output current into a first copy current by keeping a voltage of a first current path terminal of a copy transistor of a first type equal to a voltage of the second current path terminal of the output transistor, wherein the copy transistor has a second current path terminal coupled to the first current path terminal of the output transistor and a control terminal coupled to a control terminal of the output transistor;
• adjusting a voltage of a control terminal of a first transistor of the first type with an error amplifier, the first transistor having a current path coupled to the first current path terminal of the copy transistor, the error amplifier having a first input terminal coupled to the first current path terminal of the copy transistor and a second input coupled to the second current path terminal of the output transistor;
• and
• converting the first copy current into a sense voltage using a current-to-voltage converter having an input coupled to the first current path terminal of the copy transistor.

An electronic circuit comprising:

• a power transistor of a first type having a first current path terminal coupled to a first supply terminal and a second current path terminal configured to be coupled to a load;
• a driver circuit coupled to a gate terminal of the power transistor;
• and
• a current sensor circuit coupled to the power transistor, wherein the current sensor circuit comprises:
• a copy transistor of the first type having a control terminal coupled to the control terminal of the power transistor and a first current path terminal coupled to the first supply terminal;
• a first transistor of the first type having a first current path terminal coupled to a second current path terminal of the copy transistor;
• an error amplifier having a first input terminal coupled to the second current path terminal of the copy transistor, a second input terminal coupled to the second current path terminal of the power transistor, an output terminal coupled to a control terminal of the first transistor, a positive power supply terminal coupled to the first supply terminal, and a negative power supply terminal coupled to a reference supply terminal;
• and
• a current-to-voltage converter having an input coupled to the second current path terminal of the copy transistor.