Patent ID: 7106047

Claim:
An electric current detection apparatus for detecting a first current which flows in a first current path during a first conduction occasion and a second current which is smaller than said first current and flows in a second current path during a second conduction occasion which differs from said first conduction occasion, the apparatus comprising: a first conductor that is connected in said first current path, a second conductor that is connected in said second current path, a third conductor that is connected in parallel with said first conductor, a magnetic core for forming a magnetic circuit to concentrate a magnetic field produced by a current flow through said first conductor and a magnetic field produced by a current flow through said second conductor, and a magnetic sensor adapted for detecting a magnetic flux density or a magnetic field that is produced in said magnetic circuit, said magnetic sensor having a detection range that corresponds to a dynamic range of values of said current flow through said second conductor; wherein a ratio of respective values of electrical resistance of said first conductor and said third conductor is predetermined such that said flux density which is produced in said magnetic circuit due to said current flow through said first conductor is within a detection range of said magnetic sensor.