Magnetic sensor and an integrated circuit
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.
1. A magnetic sensor, comprising:
a housing;
an input port and an output port, both extending from the housing; and
an electrical circuit comprising:
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;
a state control circuit coupled with the output control circuit and configured to determine whether a predetermined condition is satisfied and signal that the predetermined condition is satisfied to the output control circuit, the predetermined condition comprising a voltage of the magnetic sensor reaching a predetermined voltage threshold for a predetermined period, wherein
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, and to operate alternately between the first state and the second state depending on a magnetic polarity of the external magnetic field and a polarity of an external alternating current (AC) power supply, wherein:
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 that of the first direction from outside of the magnetic sensor into the magnetic sensor via the output port, wherein the output control circuit is further configured to control the magnetic sensor to operate:
in the first state by allowing the load current to flow in the first direction when the magnetic induction signal indicates that the external magnetic field has a first magnetic polarity and the external AC power supply has a first polarity, and
in the second state by allowing the load current to flow in the second direction when the magnetic induction signal indicates that the external magnetic field has a second magnetic polarity opposite the first magnetic polarity and the external AC power supply has a second polarity; and
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.
2. The magnetic sensor of claim 1 , wherein the output control circuit comprises:
a first switch coupled with the output port to form a first current path for the load current to flow in the first direction; and
a second switch coupled with the output port to form a second current path for the load current to flow in the second direction, wherein
the first switch and the second switch respond respectively to the magnetic induction signal to selectively turn on the first current path and second current path, respectively.
3. The magnetic sensor of claim 1 , wherein in the third state, there is no or a negligible amount of load current flowing through the output port.
4. The magnetic sensor of claim 1 , wherein the input port is coupled with an external alternating current (AC) power supply and an operating frequency of the magnetic sensor is positively proportional to a frequency of the external AC power supply.
5. The magnetic sensor of claim 4 , further comprises a rectifier coupled with the input port and configured to convert the external AC power supply to a direct current (DC) power supply provided to the magnetic field detecting circuit.
6. The magnetic sensor of claim 1 , wherein the state control circuit comprises a voltage detecting circuit configured to detect a specific voltage and, when the specific voltage equals to or is greater than a predetermined voltage threshold, output a triggering signal.
7. The magnetic sensor of claim 6 , wherein the state control circuit further comprises
a delay circuit configured to time, upon receiving the triggering signal, a length of time during which the specific voltage equals to or is greater than the predetermined voltage threshold; and
a logic circuit configured to be responsive to the magnetic induction signal, when the length of time exceeds a predetermined length of time, to enable the output control circuit to control the magnetic sensor to operate in at least one of the first state and the second state.