Patent ID: 7112935
Filing Date: 2006-09-26
Classification: H02M

Abstract:
1. A current sensor comprising: a power MOSFET connected between an electric load and a power source, for controlling current that flows through said electric load; a mirror MOSFET connected in parallel to said power MOSFET, such that a current that flows through said mirror MOSFET is equal to a portion of a current that flows through said power MOSFET; a current detection resistor connected between a source electrode of said power MOSFET and a source electrode of said mirror MOSFET; and a converting means for converting both positive and negative voltages generated across said current detection resistor into a current detection signal that is always positive or is always negative; wherein said current detection resistor has a resistance value Rrc such that a value obtained as the result of a current Imain, which flows through said power MOSFET or a parasitic diode of said power MOSFET, divided by a mirror ratio X of said power MOSFET to said mirror MOSFET, and multiplied by the resistance value Rrc is less than a voltage drop value VD of said power MOSFET or of the parasitic diode of said power MOSFET, when said current is flowing.