Patent ID: 7310001

Claim:
A current sensing method, for sensing current flowing through a MOSFET, comprising the steps of: dividing a source-to-drain voltage of the MOSFET with a voltage divider circuit composed of a series circuit of a first resistor and a second resistor, wherein the voltage divider is connected with the MOSFET in parallel, and a voltage division ratio of the first resistor and the second resistor changes depending on temperature; and sensing the current flowing through the MOSFET from the source-to-drain voltage divided with the voltage divider, wherein when an on-resistance value of the MOSFET is denoted by Ron, a resistance value of the first resistor by R1, and a resistance value of said second resistor by R2, a value of expression Ron*R2/(R1+R2) either falls within 5% for a temperature range of not more than 50° C. or falls within 25% for a temperature range of above 50° C. to 200° C.