The present teaching relates to a method/apparatus for a magnetic sensor. The apparatus of the magnetic sensor resides in a housing and includes an input port and an output port, both extending from the housing. The apparatus also includes an electrical circuit which comprises a magnetic field detecting circuit, configured to detect an external magnetic field and output a magnetic induction signal that is indicative of information related to the external magnetic field, an output control circuit coupled between the magnetic field detecting circuit and the output port, and a state control circuit coupled with the output control circuit and configured to determine whether a predetermined condition is satisfied and signal the same to the output control circuit. When the predetermined condition is satisfied, the state control circuit is at least responsive to the magnetic induction signal to enable the output control circuit to control the magnetic sensor to operate in at least one of a first state and a second state. In the first state, a load current flows in a first direction from the output port to outside of the magnetic sensor. In the second state, a load current flows in a second direction opposite of the first direction from outside of the magnetic sensor into the magnetic sensor via the output port. When the predetermined condition is not satisfied, the state control circuit enables the output control circuit to control the magnetic sensor to operate in a third state.