Magnetic sensor and an integrated circuit
The present teaching relates to a magnetic sensor residing in a housing. The magnetic sensor includes an input port and an output port, both extending from the housing, wherein the input port is to be connected to an external alternating current (AC) power supply. The magnetic sensor also includes an electric circuit which comprises an output control circuit coupled with the output port and configured to be at least responsive to a magnetic induction signal and the external AC power supply to control the magnetic sensor to operate in a state in which a load current flows through the output port. The magnetic induction signal is indicative of at least one characteristic of an external magnetic field detected by the electrical circuit and the operating frequency of the magnetic sensor is positively proportional to the frequency of the external AC power supply.
1. A magnetic sensor, comprising:
a housing;
an input port and an output port, both extending from the housing, wherein the input port is to be connected to an external alternating current (AC) power supply; and
an electrical circuit which comprises:
an output control circuit coupled with the output port and configured to be at least responsive to a magnetic induction signal and, when a predetermined condition is satisfied, to control the magnetic sensor to operate in at least one of a first state and a second state, the predetermined condition being set as a predetermined period that a voltage of the magnetic sensor reaches a predetermined voltage threshold, 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, and
an operating frequency of the magnetic sensor is positively proportional to a frequency of the external AC power supply; and
a sub-circuit configured to determine whether the predetermined condition is satisfied, the sub-circuit further comprising:
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;
a delay circuit coupled with the voltage detecting circuit and 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 coupled with the delay circuit and configured to:
signal that the predetermined condition is satisfied, when the length of time exceeds a predetermined length of time, and
signal that the predetermined condition is not satisfied, when the length of time does not exceed the predetermined length of time.
2. The magnetic sensor of claim 1 , wherein the electrical circuit further comprises:
a magnetic field detecting circuit configured to detect an external magnetic field and output the magnetic induction signal that is indicative of at least one characteristic of the external magnetic field.
3. The magnetic sensor of claim 2 , wherein the magnetic field detecting circuit comprises:
a magnetic sensing element configured to detect the external magnetic field and output an analog electric signal that corresponds to the external magnetic field;
a signal processing element configured to amplify the analog electric signal, remove interference therefrom, and generate a processed analog electric signal; and
an analog-digital conversion element configured to convert the processed analog electric signal to the magnetic induction signal, which corresponds to a switching digital signal.
4. The magnetic sensor of claim 1 , wherein, when the predetermined condition is satisfied, the magnetic sensor operates alternately between the first and the second state, depending on a magnetic polarity of the external magnetic field and a polarity of the external AC power supply.
5. The magnetic sensor of claim 4 , wherein the output control circuit is configured to control the magnetic sensor, when the predetermined condition is satisfied, to operate
in the first state by allowing a 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 a 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 to the first magnetic polarity and the external AC power supply has a second polarity opposite to the first polarity.
6. 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 a load current to flow in the first direction; and
a second switch coupled with the output port to form a second current path for a load current to flow in the second direction, wherein
the first and second switches respond respectively to the magnetic induction signal to selectively turn on the first and second current paths, respectively.
7. The magnetic sensor of claim 1 , wherein when the magnetic sensor operates in either the first or the second state, the operating frequency of the magnetic sensor is the same as the frequency of the external AC power supply.
8. The magnetic sensor of claim 1 , wherein the output control circuit is further configured to control, when the predetermined condition is not satisfied, the magnetic sensor to operate in a third state, in which there is no or a negligible amount of load current flowing through the output port.
9. The magnetic sensor of claim 8 , wherein the operating frequency of the magnetic sensor in the third state is twice of the frequency of the external AC power supply.
10. The magnetic sensor of claim 1 , wherein the electrical circuit further comprises a rectifier configured to rectify in full wave the external AC power supply to generate an output voltage having a frequency twice of the operating frequency of the magnetic sensor in the first or the second state.
11. A magnetic sensor, comprising
a housing;
an input port extending from the housing and coupled with an external alternating current (AC) power supply;
an output port extending from the housing; and
an electrical circuit which comprises:
an output control circuit coupled with the output port and configured to be at least responsive to a magnetic induction signal, the external AC power supply and, when a predetermined condition is satisfied, to control the magnetic sensor to operate in a first state in which a load current flows through the output port and a second state in which the load current flows to the magnetic sensor from the output port, the predetermined condition being set as a predetermined period that a voltage of the magnetic sensor reaches a predetermined voltage threshold, the output control circuit comprising:
a sub-circuit configured to determine whether the predetermined condition is satisfied, the sub-circuit further comprising:
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;
a delay circuit coupled with the voltage detecting circuit and 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 coupled with the delay circuit and configured to:
signal that the predetermined condition is satisfied, when the length of time exceeds a predetermined length of time, and
signal that the predetermined condition is not satisfied, when the length of time does not exceed the predetermined length of time, wherein
the magnetic induction signal is indicative of at least one characteristic of an external magnetic field detected by the electrical circuit, and
the operating frequency of the magnetic sensor is positively proportional to the frequency of the external AC power supply.