WO2021251085A1

WO2021251085A1 - Magnetic sensor

Info

Publication number: WO2021251085A1
Application number: PCT/JP2021/018985
Authority: WO
Inventors: 美穂前
Original assignee: 株式会社村田製作所
Priority date: 2020-06-12
Filing date: 2021-05-19
Publication date: 2021-12-16

Abstract

This magnetic sensor (100) comprises a VDD terminal (VDD), a CLK terminal (CLK), an output terminal (OUT), an MR terminal (110), a comparator (120), a DFF circuit (130), and an output circuit (140). The VDD terminal receives a constant-voltage signal. The CLK terminal receives a pulsed intermittent signal. The comparator compares a first sensing signal and a second sensing signal from the MR terminal. The DFF circuit is driven by the constant-voltage signal from the VDD terminal, and retains the output signal from the comparator in response to the intermittent signal from the CLK terminal. The output circuit converts the signal level outputted from the output terminal on the basis of a first signal retained by the DFF circuit. The MR terminal and the comparator are driven in accordance with the intermittent signal from the CLK terminal. The comparator forms output signal hysteresis on the basis of the first signal from the DFF circuit.

Description

Magnetic sensor

The present disclosure relates to a magnetic sensor, and more specifically, to a technique for stabilizing an output signal in the magnetic sensor.

A magnetic sensor that detects a magnetic field using a magnetoelectric conversion element such as a Hall element or a magnetoresistive (MR) element is known. In a magnetic sensor in which an MR element is used as a magnetoelectric conversion element, the MR element has a Wheatstone bridge circuit formed by four resistance elements including two resistance elements whose resistance value is lowered by an external magnetic field. .. The magnetic sensor detects a magnetic field in an MR element by utilizing a change in the intermediate potential difference of a bridge circuit caused by an external magnetic field.

Japanese Patent No. 5636991 (Patent Document 1), Japanese Patent Application Laid-Open No. 2000-356530 (Patent Document 2) and Japanese Patent Application Laid-Open No. 2000-174254 (Patent Document 3) describe magnetic sensors using MR elements as described above. Is disclosed.

Japanese Patent No. 5636991 Japanese Unexamined Patent Publication No. 2000-356530 Japanese Unexamined Patent Publication No. 2000-174254

In recent years, there has been an increasing demand for miniaturization of magnetic sensors, and along with this, miniaturization of magnetic-electric conversion elements used in magnetic sensors is also required. Generally, the magnetic-electric conversion element used in a magnetic sensor is formed by a semiconductor element formed in a thin film or an alloy thin film. When the magnetic-electric conversion element is miniaturized, the area of the thin film becomes smaller, so that the resistance value of the magnetic-electric conversion element itself increases. Then, the power consumption in the magnetic-electric conversion element increases accordingly, and the heat generation of the magnetic-electric conversion element may also increase.

In response to such a problem, in the above patent document, power consumption is reduced by supplying a pulse-shaped intermittent power supply to the magnetic-electric conversion element and shortening the driving time of the magnetic-electric conversion element.

On the other hand, when the magnetic-electric conversion element is externally intermittently driven, the output from the magnetic sensor becomes an intermittent output, or the output signal is repeatedly turned on and off when the presence or absence of an external magnetic field is gradually switched. Chattering is likely to occur, and the output signal may become unstable.

The present disclosure has been made to solve the above-mentioned problems, and an object thereof is to stabilize an output signal while reducing power consumption in a magnetic sensor.

The magnetic sensor according to the present disclosure includes a first terminal and a second terminal, an output terminal, a magnetic-electric conversion element, a comparator, a holding circuit, and an output circuit. The first terminal receives a constant voltage signal. The second terminal receives a pulsed intermittent signal. The comparator compares the first detection signal and the second detection signal from the magnetic-electric conversion element. The holding circuit is driven by a constant voltage signal from the first terminal and holds the output signal of the comparator in response to the intermittent signal from the second terminal. The output circuit switches the signal level output from the output terminal based on the first signal held in the holding circuit. The magnetic conversion element and the comparator are driven corresponding to the intermittent signal from the second terminal. The comparator forms a hysteresis of the output signal based on the first signal from the holding circuit.

According to the magnetic sensor according to the present disclosure, a constant voltage signal and an intermittent signal are received from the outside as a power source for driving the circuit. Since the magnetic conversion element and the comparator are intermittently driven in response to the intermittent signal, the power consumption can be reduced as compared with the case where they are constantly driven. Further, since the holding circuit is driven by a constant voltage signal, even if the output of the comparator disappears due to intermittent driving, the signal for output to the output terminal can be kept held. Further, by forming the hysteresis of the comparator based on the output signal of the holding circuit, chattering of the output signal can be appropriately suppressed. Therefore, in the magnetic sensor, the output signal can be stabilized while reducing the power consumption.

It is a circuit diagram for demonstrating the magnetic sensor which concerns on embodiment. It is a timing chart in the magnetic sensor of FIG. It is a circuit diagram of the magnetic sensor of the comparative example. It is a timing chart in the magnetic sensor of FIG. It is a circuit diagram of the magnetic sensor of a modification.

Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. The same or corresponding parts in the drawings are designated by the same reference numerals and the description thereof will not be repeated.

(Magnetic sensor configuration)
FIG. 1 is a circuit diagram for explaining the magnetic sensor 100 according to the embodiment. With reference to FIG. 1, the magnetic sensor 100 has a CLK terminal, a VDD terminal, an output terminal OUT, a ground terminal GND, an MR element 110, a comparator 120, a DFF (D flipflop) circuit 130, and an output. It includes a circuit 140, a pulse generation circuit 150, and a switch (GSW) 160.

The VDD terminal receives a constant voltage signal for a power supply supplied from the outside. The constant voltage signal received at the VDD terminal is supplied to the MR element 110, the comparator 120, the DFF circuit 130, and the output circuit 140.

In addition, the CLK terminal receives an intermittent drive signal having a pulse shape from the outside. The intermittent signal received at the CLK terminal is supplied to the pulse generation circuit 150. The pulse generation circuit 150 receives the intermittent signal supplied from the CLK terminal and generates a pulse signal (second signal) having the same period as the intermittent signal and having a pulse width shorter than that of the intermittent signal. The pulse signal generated by the pulse generation circuit 150 is supplied to the DFF circuit 130 circuit and the switch 160.

The MR element 110 is a magneto-electric conversion element that converts a change in an external magnetic field into an electric signal. As the MR element 110, an AMR (Anisotropic Magneto Resistance) element, a GMR (Giant Magneto Resistance) element, a TMR (Tunnel Magneto Resistance) element, a BMR (Ballistic Magneto Resistance) element, a CMR (Colossal Magneto Resistance) element, or the like can be used. can.

The MR element 110 is connected in series with the switch 160 between the VDD terminal and the ground terminal GND connected to the reference potential. The MR element 110 includes four resistance elements R1 to R4 forming a bridge circuit. More specifically, one end of the resistance element R1 is connected to the VDD terminal, and the other end is connected to one end of the resistance element R2. The other end of the resistance element R2 is connected to the switch 160. Further, one end of the resistance element R3 is connected to the VDD terminal, and the other end is connected to one end of the resistance element R4. The other end of the resistance element R4 is connected to the switch 160. That is, the directly connected resistance elements R1 and R2 and the directly connected resistance elements R3 and R4 are connected in parallel.

The resistance elements R2 and R3 have a characteristic that the resistance value becomes smaller when the magnetic field strength of the external magnetic field becomes larger than a predetermined sensitivity threshold value. Therefore, when there is an external magnetic field (when the magnetic field strength of the external magnetic field is larger than the sensitivity threshold value of the MR element 110), the potential of the connection node N1 between the resistance element R1 and the resistance element R2 (first detection signal). ) Is smaller than in the absence of an external magnetic field. On the other hand, the potential (second detection signal) of the connection node N2 between the resistance element R3 and the resistance element R4 becomes larger when there is an external magnetic field than when there is no external magnetic field.

The switch 160 is a switch for switching between supplying and shutting off the power supply to the MR element 110. The switch 160 is, for example, an N-type MOSFET (Metal-Oxide-Semiconductor Field-Effect Transistor), and is in a conductive state when the pulse signal generated by the pulse generation circuit 150 is at a high level, and is non-conducting when the pulse signal is at a low level. It becomes. That is, power is supplied to the MR element 110 according to the pulse signal generated by the pulse generation circuit 150.

The comparator 120 has a positive power supply terminal, a negative power supply terminal, an inverting input terminal, a non-inverting input terminal, and an output terminal. The positive power supply terminal is connected to the VDD terminal. The negative power supply terminal is connected to the connection node N3 between the MR element 110 and the switch 160. Therefore, similarly to the MR element 110, power is supplied to the comparator 120 according to the pulse signal generated by the pulse generation circuit 150.

The inverting input terminal of the comparator 120 is connected to the connection node N1 between the resistance element R1 and the resistance element R2 in the MR element 110. Further, the non-inverting input terminal is connected to the connection node N2 between the resistance element R3 and the resistance element R4. If the MR element 110 is set so that the potential of the connection node N1 is higher than the potential of the connection node N2 when there is no external magnetic field, it is non-inverting with the inverting input terminal of the comparator 120 in the absence of an external magnetic field. Since a negative potential difference is generated between the input terminal and the input terminal, the output of the comparator 120 becomes low level. On the other hand, when there is an external magnetic field, the potential of the connection node N1 decreases and the potential of the connection node N2 increases, so that a positive potential difference occurs between the inverting input terminal and the non-inverting input terminal of the comparator 120. As a result, the output of the comparator 120 becomes a high level.

In other words, if the deviation obtained by subtracting the signal input to the inverting input terminal (second detection signal) from the signal input to the non-inverting input terminal (first detection signal) is larger than the predetermined threshold value, the comparator The output signal from 120 becomes high level, and when the deviation is smaller than the threshold value, the output signal from the comparator 120 becomes low level.

The DFF circuit 130 has a data terminal D, a clock terminal C, and an output terminal Q. The data terminal D is connected to the output terminal of the comparator 120 and receives the output signal of the comparator 120. The clock terminal C receives a trigger signal for holding the signal received at the data terminal D. The clock terminal C receives a signal in which the pulse signal (second signal) from the pulse generation circuit 150 is inverted. Therefore, the DFF circuit 130 holds the state of the output signal of the comparator 120 at the falling timing of the pulse signal (second signal) from the pulse generation circuit 150, and outputs the held signal (first signal) to the output terminal Q. Output from. The output terminal Q of the DFF circuit 130 is connected to the output circuit 140.

The DFF circuit 130 is driven by a constant voltage signal from the VDD terminal, and the drive / stop is not switched by the intermittent signal from the CLK terminal. Therefore, even if the power supply to the comparator 120 is stopped in response to the pulse signal from the pulse generation circuit 150 and the output signal from the comparator 120 disappears, the output signal from the DFF circuit 130 is maintained.

The output circuit 140 includes switches SW1 and SW2 connected in series between the VDD terminal and the ground terminal GND. The switch SW1 is an N-type MOSFET and is connected to the VDD terminal. The switch SW2 is a P-type MOSFET and is connected to the ground terminal GND. The connection node N4 between the switch SW1 and the switch SW2 is connected to the output terminal OUT.

Each control terminal of the switches SW1 and SW2 is connected to the output terminal Q of the DFF circuit 130. Therefore, when the output of the DFF circuit 130 is high level (that is, when there is an external magnetic field), the signal level output from the output terminal OUT becomes high level, and when the output of the DFF circuit 130 is low level (that is, when there is an external magnetic field). That is, when there is no external magnetic field), the signal level from the output terminal OUT becomes low level.

Further, the output signal (first signal) from the DFF circuit 130 is also fed back to the comparator 120. The output signal from the DFF circuit 130 is supplied to the HYS terminal of the comparator 120. The HYS terminal is a terminal for changing a determination threshold value used for comparing two input signals in the comparator 120 to give a trigger for forming a hysteresis of an output signal.

More specifically, when the output signal of the DFF circuit 130 received at the HYS terminal is at a high level, the above threshold value is made smaller than when it is at a low level. As a result, when the output signal of the DFF circuit 130 is at a high level (that is, when there is an external magnetic field), the threshold value for determination of the comparator 120 is set as compared with the case where the output signal of the DFF circuit 130 is at a low level. It gets smaller. Therefore, in the comparator 120, when the deviation (difference voltage) between the two signals from the MR element 110 becomes sufficiently lower than the deviation when the output signal changes from low level to high level, the output of the comparator 120 Will change from high level to low level. That is, the hysteresis of the output signal of the comparator 120 is formed based on the output signal (first signal) from the DFF circuit 130.

When the MR element 110 is placed in an environment of magnetic field strength near the sensitivity threshold value, it takes a short time due to the influence of a slight change in the magnetic field strength or electrical noise in the detection circuit of the magnetic sensor 100. During this period, the output of the comparator 120 repeats high level and low level, so-called chattering phenomenon may occur. As described above, in the comparator 120, chattering of the output signal of the comparator 120 can be prevented by forming a hysteresis based on the output of the DFF circuit 130.

As described above, the comparator 120 is driven in response to the pulse signal from the pulse generation circuit 150 in order to reduce power consumption. Therefore, when the hysteresis is formed by using the output signal of the comparator 120, the hysteresis is reset every time the power supply to the comparator 120 is cut off. On the other hand, since the DFF circuit 130 is driven by a constant voltage signal from the VDD terminal, the hysteresis is formed based on the output signal of the DFF circuit 130, so that the hysteresis is irrespective of the power supply state to the comparator 120. The trigger signal for formation can be maintained. As a result, the occurrence of chattering can be appropriately suppressed, and as a result, the output of the magnetic sensor can be further stabilized.

In the magnetic sensor 100 of the embodiment, the "VDD terminal" and the "CLK terminal" correspond to the "first terminal" and the "second terminal" of the present disclosure, respectively. The "DFF circuit 130" in the embodiment corresponds to the "holding circuit" in the present disclosure.

Next, the detailed operation of the magnetic sensor 100 of FIG. 1 will be described with reference to FIG. FIG. 2 is a timing chart of the magnetic sensor 100 of FIG. In FIG. 2, the presence / absence of an external magnetic field, the constant voltage signal received at the VDD terminal, the intermittent signal received at the CLK terminal, the power consumption of the magnetic sensor 100, and the output signal output from the output terminal OUT are shown from the upper stage. ..

With reference to FIGS. 1 and 2, for example, consider a case where the magnetic force of a magnet attached to a rotating shaft of a motor or the like is detected by a magnetic sensor 100. In this case, a state with an external magnetic field and a state without an external magnetic field appear alternately. In FIG. 2, between time t0 and time t6 and after time t11 corresponds to a state where there is an external magnetic field.

At time t1, the magnetic sensor 100 is activated and a constant voltage signal is supplied to the VDD terminal. Further, an intermittent signal having a predetermined period is supplied to the CLK terminal. When the constant voltage signal is supplied, the DFF circuit 130, the output circuit 140, and the pulse generation circuit 150 are driven, and the power generated by these devices is consumed. At this time, since the switch 160 is in a non-conducting state, power is not consumed in the MR element 110 and the comparator 120. The state in which only the DFF circuit 130, the output circuit 140, and the pulse generation circuit 150 are driven is also referred to as a "base state" below.

When the pulse of the intermittent signal is received at time t2, the pulse generation circuit 150 generates a pulse signal having a pulse width shorter than that of the intermittent signal, and the switch 160 is put into a conductive state. The MR element 110 and the comparator 120 are driven only during the time t2 to t3 when the switch 160 is in the conduction state, and the detection of the external magnetic field at the position where the magnetic sensor 100 is attached is performed. This increases power consumption.

Since there is an external magnetic field at times t2 to t3, the resistance values of the resistance elements R2 and R3 of the MR element 110 decrease due to the external magnetic field, and the output of the comparator 120 becomes a high level. Since the signal is not updated in the DFF circuit 130 between the times t2 and t3, the output of the output circuit 140 remains at the low level.

At time t3, when the pulse signal from the pulse generation circuit 150 falls, the input signal of the clock terminal C of the DFF circuit 130 changes to a high level at that timing. In response to this, the DFF circuit 130 holds the input signal of the data terminal D (that is, the output of the comparator 120) at that timing. At time t3, since there is an external magnetic field and the output of the comparator 120 is high level, the output signal from the output terminal Q of the DFF circuit 130 transitions from low level to high level. As a result, the output signal from the output circuit 140 also becomes a high level.

Further, at time t3, the pulse signal from the pulse generation circuit 150 becomes low level, so that the switch 160 is switched to the non-conducting state. As a result, the supply of the constant voltage signal to the MR element 110 and the comparator 120 is stopped, so that the power consumption is reduced to the level of the base state.

Although the output signal drops to a low level due to the stop of the comparator 120 at time t3, the high level state is maintained in the DFF circuit 130, and the constant voltage signal continues in the DFF circuit 130 and the output circuit 140. The output signal from the output terminal OUT continues to be in a high level state.

At time t4, the intermittent signal is supplied again to the CLK terminal, and the pulse signal from the pulse generation circuit 150 becomes high level, but since the state of the external magnetic field has not changed, even if the pulse signal falls at time t5. , The signal state held in the DFF circuit 130 does not change, and the output from the output circuit 140 also maintains a high level state.

At time t6, there is no external magnetic field, but at this point, the MR element 110 and the comparator 120 are not driven, so the state of the output signal from the output terminal OUT does not change.

When the intermittent signal is supplied at time t7 and the MR element 110 and the comparator 120 are driven by the pulse signal from the pulse generation circuit 150, the MR element 110 detects a state in which there is no external magnetic field. As a result, the output of the comparator 120 changes from high level to low level. Then, at the timing of the fall of the pulse signal at time t8, the signal holding state of the DFF circuit 130 is updated, and the state of the output signal from the output terminal OUT transitions from the high level to the low level.

The intermittent signal is supplied again at time t9, but since the state without an external magnetic field continues, the signal holding state of the DFF circuit 130 and the state of the output signal from the output terminal OUT at the falling edge of the pulse signal at time t10. Maintains a low level.

When the external magnetic field changes to a certain state again at time t11, the external magnetic field is detected by the MR element 110 at the pulse signal supply timing (time t12) immediately after that. Then, at the falling timing of the pulse signal at time t13, the signal holding state of the DFF circuit 130 is updated, and the state of the output signal from the output terminal OUT transitions from the low level to the high level. After that, the operation between the times t2 and t13 is repeated according to the state of the external magnetic field.

Since the hysteresis in the comparator 120 is performed based on the output signal of the DFF circuit 130 (that is, the output signal from the output terminal OUT), the comparator 120 is in a state where the magnetic sensor 100 recognizes that there is an external magnetic field. The threshold value for magnetic field detection in is continuously lowered. Therefore, even if the MR element 110 and the comparator 120 are intermittently driven, hysteresis is appropriately realized.

As described above, in the magnetic sensor 100, since the MR element 110 and the comparator 120 are driven only during the minute pulse signal generated from the intermittent signal received at the CLK terminal, the MR element 110 and the comparator 120 are driven, as compared with the case where these devices are always in the driving state. Therefore, the power consumption of the entire magnetic sensor 100 can be reduced. Further, by forming the hysteresis of the comparator 120 based on the output signal of the DFF circuit 130, the trigger signal for forming the hysteresis can be maintained regardless of the power supply state to the MR element 110 and the comparator 120. The output of the magnetic sensor can be more stabilized.

FIG. 3 is a circuit diagram of the magnetic sensor 100 # of the comparative example. With reference to FIG. 3, the magnetic sensor 100 # basically includes the same elements as the magnetic sensor 100 of the embodiment. Compared with the magnetic sensor 100, the magnetic sensor 100 # has a point that the power supplied to the apparatus is only an intermittent signal and a point that the hysteresis of the comparator 120 using the output signal of the DFF circuit 130 is not formed. Is different. That is, all of the MR element 110, the comparator 120, the DFF circuit 130, and the output circuit 140 are intermittently driven by the intermittent signal. In addition, in FIG. 3, the description of the element overlapping with FIG. 1 is not repeated.

FIG. 4 is a timing chart of the magnetic sensor 100 # of FIG. In FIG. 4, the presence / absence of an external magnetic field, the intermittent signal received at the VDD terminal, the power consumption of the magnetic sensor 100, and the output signal output from the output terminal OUT are shown from the upper stage. FIG. 4 shows a case where a state with an external magnetic field and a state without an external magnetic field appear alternately as in FIG. 2.

With reference to FIGS. 3 and 4, in the case of the magnetic sensor 100 #, the magnetic sensor 100 # is driven only while the intermittent signal is at a high level at the VDD terminal. When an intermittent signal is supplied to the VDD terminal during a period of time t20 to t27 with an external magnetic field (time t21), the switch 160 is brought into a conductive state by the pulse signal from the pulse generation circuit 150, and the MR element 110 And power is supplied to the comparator 120. The DFF circuit 130 and the output circuit 140 are also driven by the intermittent signal. This increases power consumption.

While the pulse signal from the pulse generation circuit 150 is at a high level (time t21 to t22), the external magnetic field is detected by the MR element 110, and the output of the comparator 120 transitions from the low level to the high level. Then, at the falling timing of the pulse signal (time t22), the output signal of the comparator 120 is held by the DFF circuit 130, and the output signal of the output circuit 140 transitions to a high level.

Since the switch 160 is in a non-conducting state between the times t22 and t23, the MR element 110 and the comparator 120 do not consume power, but only the power consumed by the DFF circuit 130, the output circuit 140, and the pulse generation circuit 150.

When the intermittent signal becomes low level at time t23, the DFF circuit 130, the output circuit 140, and the pulse generation circuit 150 are also stopped, so that the power consumption becomes zero. As a result, the output signals of the DFF circuit 130 and the output circuit 140 become low level, so that the output of the output terminal OUT becomes low level even though there is an external magnetic field.

When the intermittent signal is supplied again at the time t24, the same operation as the time t21 to t23 is executed, and the output signal from the output terminal OUT becomes high level only during the time t25 to t26.

In the state where there is no external magnetic field between the times t27 and t34, the magnetic field is not detected by the MR element 110 even if the intermittent signal is supplied, so that the output signal from the output terminal OUT remains at a low level. When the external magnetic field is present again at the time t34, the output signal from the output terminal OUT becomes high level only between the times t36 and t37 while the intermittent signal is being supplied.

As described above, in the magnetic sensor 100 # of the comparative example, the power consumption is consumed only while the intermittent signal is supplied, so that the power consumption of the entire device can be significantly reduced. However, in the magnetic sensor 100 #, even if the state where there is an external magnetic field continues, the output signal from the output terminal OUT becomes low level only while the intermittent signal is at high level. Therefore, in order to correctly detect the state of the external magnetic field, the output signal is taken into consideration by the external control device that processes the output signal of the magnetic sensor 100 # while considering the timing between the intermittent signal and the output signal of the magnetic sensor 100 #. It is necessary to separately form a circuit for holding the.

In comparison with this, in the magnetic sensor 100 of the embodiment shown in FIGS. 1 and 2, the DFF circuit 130 and the DFF circuit 130 and the intermittent drive of the MR element 110 and the comparator 120 are received from the outside by receiving a constant voltage signal and an intermittent signal. By constantly driving the output circuit 140, it is possible to bring the output signal from the output terminal OUT closer to the state of the actual external magnetic field while reducing the power consumption to some extent. Therefore, the holding circuit in the external control device becomes unnecessary.

Further, in the magnetic sensor 100 of the embodiment, since the hysteresis of the comparator 120 is formed by using the output signal of the DFF circuit 130, chattering of the output signal at the boundary between the state with the external magnetic field and the state without the external magnetic field. Can be suppressed. Therefore, in the magnetic sensor 100 of the embodiment, the output signal can be stabilized while reducing the power consumption.

(Modification example)
In the magnetometer 100 of the above embodiment, a case where an MR element is used as a magnetoelectric conversion circuit has been described. In the modification, a case where a Hall element is used as the magnetic-electric conversion circuit will be described.

FIG. 5 is a circuit diagram of the magnetic sensor 100A according to the modified example. The magnetic sensor 100A has a configuration in which the MR element 110 in the magnetic sensor 100 shown in FIG. 1 is replaced with the Hall element 110A. In FIG. 5, the detailed description of the elements overlapping with FIG. 1 is not repeated.

The Hall element 110A is connected in series with the switch 160 between the VDD terminal and the ground terminal GND. The Hall element 110A generates an electromotive force (Hall voltage) proportional to the magnitude of the external magnetic field between the output terminals T1 and T2. Therefore, the presence or absence of an external magnetic field can be detected by connecting the output terminals T1 and T2 to the non-inverting input terminal and the inverting input terminal of the comparator 120, respectively, and comparing the Hall voltage with a predetermined threshold value.

Then, it receives a constant voltage signal and an intermittent signal from an external device, and while intermittently driving the Hall element 110A and the comparator 120, it constantly drives the DFF circuit 130 and the output circuit 140, and further, the comparator using the output signal of the DFF circuit 130. By forming the hysteresis of 120, the output signal can be stabilized while reducing the power consumption of the magnetic sensor.

The embodiments disclosed this time should be considered to be exemplary in all respects and not restrictive. The scope of the present disclosure is set forth by the scope of claims rather than the description of the embodiments described above, and is intended to include all modifications within the meaning and scope of the claims.

100, 100A, 100 # magnetic sensor, 110 MR element, 110A Hall element, 120 comparator, 130 DFF circuit, 140 output circuit, 150 pulse generation circuit, 160, SW1, SW2 switch, C clock terminal, D data terminal, GND grounding Terminal, N1 to N4 connection node, OUT, Q, T1, T2 output terminal, R1 to R4 resistance element.

Claims

The first terminal that receives a constant voltage signal and
The second terminal that receives the pulsed intermittent signal,
With the output terminal
Magnetic-electric conversion element and
A comparator that compares the first detection signal and the second detection signal from the magnetic conversion element, and
A holding circuit driven by a constant voltage signal from the first terminal and configured to hold the output signal of the comparator in response to an intermittent signal from the second terminal.
It is provided with an output circuit for switching the signal level output from the output terminal based on the first signal held in the holding circuit.
The magnetic conversion element and the comparator are driven in response to an intermittent signal from the second terminal.
The comparator is a magnetic sensor that forms a hysteresis of the output signal based on the first signal from the holding circuit.
The comparator is
When the deviation obtained by subtracting the second detection signal from the first detection signal is larger than the threshold value, the output signal is set to high level, and when the deviation is smaller than the threshold value, the output signal is set to low level.
The magnetic sensor according to claim 1, wherein when the first signal is at a high level, the threshold value is made smaller than when the first signal is at a low level.
The magnetic sensor according to claim 1 or 2, wherein the output circuit is driven by a constant voltage signal from the first terminal.
Further, a pulse generation circuit configured to generate a second signal having a pulse width shorter than that of the intermittent signal by using the intermittent signal from the second terminal is provided.
The magnetic sensor according to any one of claims 1 to 3, wherein the holding circuit holds the output of the comparator at the falling timing of the second signal.
The magnetic sensor according to claim 4, further comprising a switch that operates according to the second signal and switches between supply and cut of a constant voltage signal from the first terminal to the magnetic conversion element and the comparator.
The magnetoelectric conversion element is an AMR (Anisotropic Magneto Resistance) element, a GMR (Giant Magneto Resistance) element, a TMR (Tunnel Magneto Resistance) element, a BMR (Ballistic Magneto Resistance) element, a CMR (Colossal Magneto Resistance) element, or a Hall element. The magnetic sensor according to any one of claims 1 to 5.