Magnetic field sensor

Abstract

Device comprising: a magnetic field sensor (10; 24; 30; 49), a variety of switches (11; PH1-4; TST; 61, 68; 69) associated with the magnetic field sensor, and a control circuit (12; 611) configured to control at least some of the plurality of switches (11; PH1-4; TST; 61, 68; 69) to apply a spinning current scheme to the magnetic field sensor (10; 24; 30; 49), wherein the spinning current scheme comprises a plurality of phases in which different terminals of the magnetic field sensor (10; 24; 30; 49) are used for biasing and readout, to obtain a multitude of measurement signals according to the spinning current scheme from the magnetic field sensor (10; 24; 30; 49), to form a first mean of a first group of the multitude of measurement signals and to form a second mean of a second group of measurement signals different from the first group, and to provide at least one signal indicative of a disturbance based on a comparison of the first mean and the second mean.

Description

DEPARTMENT

[0001] The present application relates to magnetic field sensors and related methods. BACKGROUND

[0002] Magnetic field sensors are used in many applications to detect a magnetic field. For example, to detect position or movement, a magnet can be attached to a moving element such as a rotor or a linear, moving component. As the moving component moves, the magnetic field generated by the magnet varies, and this change can be detected by a magnetic field sensor. Such setups can be used, for example, to detect position, speed, tampering magnetic fields in smart meters, or acceleration.

[0003] Sometimes, such arrangements and magnetic field sensors are used in safety-critical applications, for example, in the automotive sector. In such applications, reliable operation of the magnetic field sensor is crucial. Furthermore, it may be necessary in such applications for the magnetic field sensor to be detectable, so that a system using the magnetic field sensor can, for example, detect a malfunction of the sensor.

[0004] In conventional approaches, redundant magnetic field sensors are sometimes provided, for example, a primary magnetic field sensor and a potentially smaller auxiliary magnetic field sensor. The primary and auxiliary magnetic field sensors may be implemented on the same bare chip. In other approaches, two separate sensor bare chips may be mounted in a single package. Outputs from the primary and auxiliary magnetic field sensors can be compared, and if they differ by more than a predetermined threshold, for example, this may indicate a fault condition.

[0005] Although providing two sensors can help meet functional safety requirements, it also requires additional chip area and therefore incurs additional costs.

[0006] EP 0 548 391 A1 discloses an offset-compensated Hall sensor with a "spinning current" readout scheme, in which switches change the function of the sensor's terminals (biasing or readout) to compensate for an offset. Similar readout methods are also known, for example, from DE 10 2004 021 863 A1 and DE 102 04 427 A1.

[0007] DE 10 2014 113 213 A1 discloses magnetic field sensors which operate with different pre-voltages.

[0008] US 2013 / 0222001 A1 discloses how to obtain information about an offset in a sensor arrangement based on switching, in particular chopper switching.

[0009] The subsequently published DE 10 2014 113 244 A1 discloses systems and methods for diagnosing a fuel control system, in which a signal supplied by an exhaust gas oxygen sensor is used.

[0010] Therefore, alternative methods for obtaining information regarding a possible malfunction or other problem with a magnetic field sensor may be desirable. SUMMARY

[0011] According to one embodiment, a device as defined in claim 1 is provided. According to another embodiment, a device as defined in claim 13 is provided. According to another embodiment, a method as defined in claim 15 is provided. The dependent claims define further embodiments. BRIEF DESCRIPTION OF THE DRAWINGS Fig. Figure 1 is a block diagram illustrating a device according to one embodiment. Fig. Figure 2 is a block diagram illustrating a device configured to apply a spinning current technique. Fig. Figure 3 is a diagram illustrating a spinning current technique. Fig. Figure 4 is a circuit diagram of a magnetic field sensor device configured to use a spinning current technique. Fig. Figure 5 illustrates example signals at an output of an analog-to-digital converter for the magnetic field sensor of Fig. 4. Fig. Figure 6 illustrates a magnetic field sensor device according to one embodiment. Fig. Figure 7 illustrates a magnetic field sensor device according to a further embodiment. Fig. Figure 8 illustrates a magnetic field sensor device according to a further embodiment. Fig. Figure 9 illustrates a magnetic field sensor device according to a further embodiment. Fig. Figure 10 illustrates an example environment for magnetic field sensor devices according to embodiments. Fig. Figure 11 is a flowchart illustrating a procedure according to one embodiment. DETAILED DESCRIPTION

[0012] The following describes various embodiments in detail with reference to the attached drawings. These embodiments are given for illustrative purposes only and should not be considered limiting. Even if embodiments are described comprehensively as comprising a multitude of features or elements, some of these features or elements may be omitted and / or replaced by alternative features or elements in other embodiments. Other embodiments may also include additional features or elements beyond those expressly shown or described.

[0013] In the embodiments described herein or shown in the drawings, any direct electrical connection or coupling, i.e., any connection or coupling without additional intermediate elements, can also be implemented by an indirect connection or coupling, i.e., a connection or coupling with one or more additional intermediate elements, or vice versa, as long as the general purpose of the connection or coupling, for example, to transmit a certain type of signal or to transmit a certain type of information, is essentially retained. Features of different embodiments can be combined to form further embodiments. For example, variations or modifications described in relation to one embodiment may also be applicable to other embodiments unless otherwise noted.

[0014] In some embodiments, a magnetic field sensor, such as a Hall sensor, can be associated with a plurality of switches. The switches can be used to implement a spinning current scheme for reading the sensor. Furthermore, in some embodiments, information regarding disturbances occurring in the magnetic field sensor device can be obtained using the switches. Examples will be discussed in more detail later.

[0015] A spinning current technique, as used here, generally involves using different terminals of a magnetic field sensor in different phases to apply a current and to read a measurement signal, such as a voltage. Examples of spinning current techniques will be discussed later, for example, in relation to the Fig. 2-5 discussed.

[0016] To now turn to the characters, illustrates Fig. 1 a magnetic field sensor device according to one embodiment.

[0017] The magnetic field sensor device of the embodiment of Fig. 1 comprises a magnetic field sensor 10. In embodiments, the magnetic field sensor 10 may comprise one or more Hall sensors, for example, planar or vertical Hall sensors. In the case of multiple Hall sensors, such Hall sensors may be connected in parallel or in series. In other embodiments, other types of magnetic field sensors may be used, for example, sensors that utilize a magnetoresistive effect (xMR sensors), such as a magnetic tunnel resistance (TMR), a giant magnetoresistive (GMR), a colossal magnetoresistive (CMR), or an anisotropic magnetoresistive (AMR).

[0018] In the embodiment of Fig. In Figure 1, the magnetic field sensor 10 is assigned to a plurality of switches 11. The switches 11 can be controlled by a control unit 12 to, for example, selectively apply a measuring current to selected terminals of the magnetic field sensor 10 and / or to selectively measure a measurement signal, for example, a voltage, at selected terminals of the magnetic field sensor 10. For example, the switches 11 can be controlled by the control unit 12 to apply a spinning current technique, as will be discussed in more detail later. Based on the measurements, the control unit 12 can output a signal a, which is indicative of a measured magnetic field.

[0019] Furthermore, the control unit 12 can output a signal b, which can be used to obtain information about a possible error or malfunction in the device. Fig. 1 to indicate or provide information, for example, a malfunction of the magnetic field sensor 10 or the switches 11. In some embodiments, the control unit 12 can evaluate the measurements during different phases of a spinning current technique for this purpose. In other embodiments, the control unit 12 can control the switches 11 to perform specific tests to detect possible malfunctions. Examples are discussed in more detail later.

[0020] It should be noted that, even if signals a and b in Fig. Figure 1 illustrates separate signals, while in other embodiments only a single signal can be output. In such a case, for example, one or more specific values ​​of the signal can be used to indicate a disturbance, while other values ​​can indicate a measured magnetic field.

[0021] It should also be noted that the device of Fig. 1 need not be a unified device, but for example part of the functions of the control unit 12 may be provided in a unit physically separate from the remaining functions, and communication between the units may take place in a wired or wireless manner.

[0022] To provide a more comprehensive understanding of the embodiments, the following section will discuss the Fig. 2-5 a spinning current technique in a magnetic field sensor device as can be used in some embodiments is described.

[0023] Fig. Figure 2 illustrates a magnetic field sensor device that can form the basis of some embodiments.

[0024] The magnetic field sensor device of Fig. 2 includes a magnetic field sensor 24. The magnetic field sensor 24 can include one or more Hall sensors, for example vertical or planar Hall sensors, but is not limited to this. To give an example, in Fig. Figure 2 illustrates two Hall sensors coupled in parallel.

[0025] A current 22 is applied to the sensor 24 via a current source. The numbers 20 and 213 indicate supply voltages. For example, the number 20 can indicate a positive supply voltage, and the number 213 can indicate ground.

[0026] In this embodiment, the precurrent generated by the power source 22 is chopped by choppers 21, 23 with a digital chopper frequency fchop.

[0027] A voltage, for example a Hall voltage, applied to the magnetic field sensor 24 in the embodiment of Fig. 2 is measured by an analog-to-digital converter. In the example of Fig. Figure 2 of the analog-to-digital converter comprises a sigma-delta analog-to-digital converter 27 with a feedback path that includes a digital integrator 211 and a digital-to-analog converter 212. However, in other embodiments, other types of analog-to-digital converters can be used, such as lag converters, successive approximation converters, pipeline converters, flash converters, or any combination thereof, to name just a few non-limiting examples. The feedback path can be provided to compensate for offset hum (ripple). Analog choppers 26, 28 and a digital chopper 29 are provided, which also operate at the chopper frequency fchop. A spinning current technique can be applied synchronously with the chopping, as indicated by an arrow 25. The number 214 indicates a magnetic field to be measured.Spinning current technology means that the terminals of sensor 25, which are used to apply the bias current, and the terminals used to measure a voltage change through the analog-to-digital converter in each of a variety of spinning current phases.

[0028] A result of the magnetic field measurement can be obtained at 210.

[0029] Such a spinning current technique is now described in more detail with regard to Fig. 3 described.

[0030] Fig. Figure 3 illustrates an example of a four-phase spinning current technique, which is used in Fig. 3 are designated as spinning current phases 1-4. Furthermore, in Fig. 3 two chopper phases are displayed. Fig. Figure 3 shows a magnetic field sensor 30 for each of the chopper phases. For ease of reference and illustration, the magnetic field sensor 30 is depicted as a bridge with four resistors. For example, in some embodiments, the sensor 30 may be a Hall sensor. In other embodiments, the sensor 30 may be an xMR sensor using a bridge configuration. The magnetic field sensor 30 is used to measure a magnetic field B.

[0031] As in Fig. As can be seen in Figure 3, the position in which the power source 31 is coupled to the sensor 30 “rotates” or “turns” from phase to phase; hence the name spinning current.

[0032] An output signal of sensor 30 in the example of Fig. 3 is a Hall voltage VH, which is amplified by a differential amplifier 32. In the example of Fig. 3. The sensor 30 may exhibit an (unintentional) asymmetry. For example, one of the illustrated resistors may differ from the other resistors by a value ΔR. Such an asymmetry may be caused by an asymmetric sensor (for example, an asymmetric Hall plate) or may result from mechanical stress experienced by the sensor.

[0033] This asymmetry causes an offset VOh of the Hall voltage VH. The addition of an amplifier offset VOa is achieved by a voltage source 33 in Fig. 3 symbolizes, which is not a real voltage source, but merely represents the offset caused by the amplifier.

[0034] With the in Fig. In the 3 illustrated spinning current technique, in phase 1 the output signal of the amplifier corresponds to 32 +VH + VOh +VOa, in spinning current phase 2 the output signal corresponds to +VH - Voh - Voa, in spinning current phase 3 to +VH + VOh +VOa and in spinning current phase 4 to +VH - Voh - VOa.

[0035] In a spinning current technique used in some embodiments, the results of all spinning current phases are added, yielding a result of 4 VH. The offsets cancel each other out. Therefore, an offset-compensated measurement can be obtained by using the spinning current technique.

[0036] Fig. Figure 4 illustrates an implementation example of a magnetic field sensor device that uses a spinning current technique. The magnetic field sensor device of Fig. Figure 4 can be used as a basis for various embodiments, some of which will be discussed in more detail later. The device of Fig. 4 comprises a magnetic field sensor 49, which, for example, includes a Hall plate or a plurality of Hall plates coupled in parallel. In other embodiments, other types of magnetic field sensors can be used. The magnetic field sensor 49 in the example of Fig. 4 comprises four terminals 45-48. In each phase of a spinning current technique, for example, two terminals of sensor 49, such as the two terminals on opposite sides, can be used to apply a bias current, and the other two terminals of sensor 49, for example, the two other terminals on opposite sides, can be used to measure a voltage such as a Hall voltage.

[0037] To implement a spinning current scheme, the embodiment of Fig. 4 four electrical conductors 41-44, which in the example of Fig. 4 surround the magnetic field sensor 49. In other embodiments, other topographies of conductors 41-44 can be used. Conductor 41 is coupled to a current source 40, which provides a bias current. Conductor 42 is coupled to a negative input of a differential amplifier 410. Conductor 43 is coupled to ground 413. Conductor 44 is coupled to a positive input of the differential amplifier 410.

[0038] The connections 45-48 as in Fig. The circuits illustrated in Figure 4 are coupled to conductors 41-44 via switches PH1-PH4. In the first phase of a spinning current technique, switches PH1 are closed and the remaining switches PH2-PH4 are open. In the second phase, all switches PH2 are closed, and the remaining switches are open. In a third spinning current phase, all switches PH3 are closed, and the remaining switches are open. A designation of the switches such as PH1 / 3 or PH2 / 4 indicates switches that are closed in two phases, e.g., phases 1 and 3 for PH1 / 3 and phases 2 and 4 for PH2 / 4. For ease of reference, these switches are included when referring to switches PH1-PH4. In a fourth spinning current phase, all switches PH4 are closed, and the remaining switches are open. Therefore, as in Figure 4, the PH1-PH4 switches are closed in the third phase. Fig. Figure 3 illustrates how, by selectively opening and closing switches PH1 to PH4, terminals 45-48 are used either as bias terminals to supply bias current or as measuring terminals to measure a voltage by the differential amplifier 410. The figures shown in Fig. The topography shown in Figure 4 is merely an example, and other arrangements of switches and conductors can be used as well.

[0039] An output from the differential amplifier 410 is provided to an analog-to-digital converter 411, which is provided with a reference voltage REF1 and / or ground. As indicated by “DEMUX”, the analog-to-digital converter 411 provides outputs for the four spinning current phases to an averaging amplifier 412, which provides an average and / or sum of the phases, possibly over a multitude of cycles, indicative of a magnetic field with compensated offsets, as in relation to Fig. 3 is explained.

[0040] Even if in the Fig. 3 and Fig. 4 and also in the embodiments described later, where four phases are illustrated, this should not be considered restrictive, and the techniques disclosed herein can also be applied to a different number of phases, in particular more than four phases (six phases, eight phases), but can also be applied to spinning current techniques that use only three phases.

[0041] Fig. Figure 5 illustrates an averaging effect through the use of a spinning current technique as employed in embodiments using example signals. The signals from Fig. The 5 are shown for illustrative purposes only, and other signal waveforms may be used in other embodiments.

[0042] Arrows in Fig. Figure 5 illustrates a current direction (bias current) in phases PH1-PH4. Curve 50 shows an example of a measurement result, including an offset, that occurs in a signal measured in one of the spinning current phases. Figure 51 denotes a zero value. Figure 52 illustrates the effect of an offset when the results of spinning current phases 1 and 2 are summed, and Figure 53 illustrates the effect of an offset when the results of spinning current phases 3 and 4 are summed. As can be seen, the offset in curves 52 and 53 is already greatly reduced compared to the offset occurring in curve 50. Furthermore, the offset according to curve 53 exhibits the opposite behavior to the offset according to curve 52, and averaging curves 52 and 53 can further cancel out the effect of the offset.The fact that the offset is already largely eliminated when only two adjacent phases are summed is used in some embodiments to detect disturbances, as explained below.

[0043] Next, regarding Fig. 6-9 different designs of magnetic field sensor devices are discussed. The magnetic field sensor devices of Fig. Figures 6 to 9 are for illustrative purposes and are based on the magnetic field sensor device of Fig. 4, and identical reference symbols are used to denote similar or corresponding elements that are not described again for the sake of brevity.

[0044] Fig. Figure 6 illustrates a magnetic field sensor device according to one embodiment. In the embodiment of Fig. 6 is a magnetic field sensor 49, for example a Hall sensor, provided, which is similar to Fig. 4 is which can be selectively coupled to conductors 41-44 via switches PH1-PH4 to implement a spinning current technique as described above. In addition to measuring a magnetic field using a spinning current technique as described above, the device can be used by Fig. It provides 6 different diagnostic functions to, for example, detect errors, malfunctions, or failures in the magnetic field sensor device. Even though a variety of different diagnostic functions are available with regard to... Fig. 6 and in relation to other embodiments, it should be understood that this is not to be considered restrictive, and that other embodiments may only implement one or some of the described diagnostic functions.

[0045] An example of a diagnostic function, which in the embodiment of Fig. 6. This can be implemented based on providing partial sums over only some of the results of the spinning current phases. As above regarding Fig. As explained in section 3, in a conventional four-phase spinning current technique, the four phases can be summed to cancel out offsets. In the embodiment of Fig. 6. A switch 65 can, for example, provide the signals of the first two phases of a four-phase spinning current technique to a first averaging unit 66 and, for example, the outputs from the third and fourth phases to a second averaging unit 67. The averaging units 66 and 67 can be used to form an average of the supplied signals in some embodiments. The average can be formed over more than one measurement cycle, where a measurement cycle comprises four phases in the example shown. In other embodiments, the averaging units 66 and 67 can form an average over signals from different phases in one measurement cycle.

[0046] For example, the first averaging unit 66 can calculate an average of the measurement results from a first and second spinning current phase, as in Fig. Figure 6 illustrates output, and the averaging tool 67 can calculate the mean of a sum of the measurement results of the third and fourth spinning current phases as shown in Fig. Output 3 as signal d. As in relation to Fig. As illustrated in Figure 5 above, the offsets for two adjacent phases (for example, 1 and 2 or 3 and 4) essentially cancel each other out. Therefore, in fault-free operation, signal c should be approximately equal to signal d (see signals 52 and 53 for examples). Fig. 5) If the difference between signals c and d is greater than a predetermined threshold, this may indicate a fault, for example, a fault in one of the switches involved. Therefore, in embodiments, fault detection can be implemented by providing two partial sums instead of one sum across all spinning current phases.

[0047] It should be noted that in some embodiments, switch 65 may be configured to modify the partial sums. For example, as mentioned above, the signal c can be a sum of the spinning current phases 1 and 2 of Fig. 3, and signal d can correspond to a sum of the spinning current phases 3 and 4 in one embodiment. In some embodiments, the switch 65 can then modify the signals provided for the averaging units 66, 67, such that, for example, signal c is a sum of the results of the spinning current phases 1 and 4 of Fig. Signal 3 is the result of the spinning current phases 2 and 3. This summation allows further comparison of signals c and d, and if they differ by more than a predetermined threshold, this can indicate a fault, such as a malfunction of one or more of the switches. Additional redundancy can be provided by supplying different partial sums as explained above.

[0048] Furthermore, by outputting signals c and d to another unit, for example a system, redundancy can be achieved in some embodiments even during error-free operation, since each of the signals c and d provides at least an approximate correct value. Providing such redundancy can increase functional safety.

[0049] Additionally or alternatively, in some embodiments, a different summation of the results of spinning current phases can be performed to obtain a value of the offset.

[0050] Even when in normal spinning current mode, as in Fig. 3. The summation is performed to cancel the offset and obtain the Hall voltage. For testing or diagnostic purposes, the sum can be calculated so that the Hall voltage (or other voltage to be measured) is canceled out, and only the offset is measured. In the example of Fig. 3. This can be achieved, for example, by subtracting, instead of adding, the signals output by the analog-to-digital converter 411 in phases 2 and 4 into the total sum, so that for these phases the output result is essentially -VH + Vah + VOa in the example of Fig. 3. Summing the results of all phases then yields 4 VOh + 4 VOa, i.e., a measurement of the offset. The offset can, for example, be compared to a predetermined threshold in various configurations. An offset above a threshold can, for example, indicate disturbances such as high leakage currents in switches PH1...PH4 and / or cases where one of the switches is defective and, for example, cannot close or remains closed continuously.

[0051] Controlling the switches for both the spinning current mode and for diagnostics to obtain the offset can be performed by a control unit 611, which is controlled by a counter 612 that counts from 1 to 4 for four spinning current phases. An operating mode can be determined by a PHTST enable signal. For example, an operating mode can be switched between a regular spinning current mode, in which the Hall voltage is determined, and a test mode, in which the offset is determined, as explained above. The counter 612 can be clocked by a clock signal clk. Furthermore, in a test mode, switches PH1...PH4 and additional switches TSTa to TSTd can be controlled as explained below.

[0052] Furthermore, an additional conductor 60 can be provided, which is connected to the terminals 45-48 of the magnetic field sensor 49 via test switches TSTa to TSTd as shown in Fig. Figure 6 illustrates that it can be selectively coupled. Furthermore, the conductor 60 can be connected to current sources via the switches 68, 69 as shown in Fig. Figure 6 illustrates selective coupling. This coupling of conductor 60 to current sources, together with the closing of the respective switches TSTd, can be used to isolate fault currents from the device. Fig. 6. Injecting fault currents can be used in some embodiments to verify the correct functioning of provided diagnostic functions. For example, injecting a fault current through one of the switches TSTa to TSTd should result in a fault that is detected by evaluating signals c and d as explained above. If no fault is detected, this may indicate a malfunction of the diagnostic function.

[0053] In some embodiments, such injection tests, in which a fault current is injected, can be performed only at startup, providing at least some latent fault diagnosis. In other embodiments, such injection tests can be performed additionally or alternatively during operation, e.g., during the actual use of a sensor device. In such a case, the injection tests can be properly handled in an additional measurement phase (e.g., by testing a switch TSTa to TSTd in each complete measurement cycle, to give a non-limiting example).

[0054] Furthermore, in some embodiments, the injection of a current via switch 68 or via switch 69 can be used to detect short circuits or leakage currents. For example, a fault current can be provided for any of the conductors 41-44 via switches PH1-PH4 and TSTa-d and should not occur on any of the other conductors if the conductors are properly insulated from each other.

[0055] For further testing purposes, some embodiments may provide switches 61 which can be used to couple another analog-to-digital converter 63 either to one of the connectors 41, 43 or to a reference input of an analog-to-digital converter 411 via connector 610. The additional analog-to-digital converter 63 may be an analog-to-digital converter that may also be provided for other purposes, as indicated by switch 62, for example, for temperature measurement. In embodiments, the analog-to-digital converter 63 can be used to perform additional test procedures besides temperature measurement.By using an analog-to-digital converter 63, which is already provided for other purposes such as temperature measurements, also to provide diagnostic functions for the magnetic field sensor device, chip area can be saved in some embodiments compared to a case in which an additional analog-to-digital converter is provided.

[0056] Switches 61 and 62 can be controlled by a control unit 64 (which is separate from the control unit 611 in Fig. (as shown in Figure 6, but which can also be implemented in a single control unit with the control unit 611) to selectively provide signals to the analog-to-digital converter 63. As indicated by a demultiplexer DEMUX, the analog-to-digital converter 63 can then output different signals depending on a test being performed. The control unit 64 can be controlled by a VTST enable signal to select a test or measurement to be performed.

[0057] In the embodiment of Fig. 6. The analog-to-digital converter 63 uses a different reference / bias voltage (in Fig. 6 (designated as REF2 / GND) than the analog-to-digital converter 411. Therefore, in some embodiments, the analog-to-digital converter 63 can measure the reference voltage of the analog-to-digital converter 411 via the conductor 610 and respective switches 61 and output a corresponding display (as code Vref in Fig. 6). In this way, in some embodiments, the reference voltage of the analog-to-digital converter 411 can be tested. Furthermore, by closing the appropriate switches 61, which are coupled to the conductors 41, 43, the bias voltage between the conductors 41, 43, which was generated by the bias current source 40, can be measured and output (as code Vbias in Fig. 6). In this way, embodiments can test whether a correct bias voltage is provided for the Hall sensor device 49.

[0058] Such diagnostic functions can be performed, for example, as a start-up test or cyclically or as a diagnostic test signal provided by a system (e.g., if any anomaly has been detected, performing a complete system check before transitioning to any fault state), or in parallel with normal operation using additional analog-to-digital converters (or simplified comparators or even window comparators, which can be seen as analog-to-digital converters with one or two bit output).

[0059] When switches 62 are closed and switches 61 are open, the analog-to-digital converter 63 can, for example, measure a temperature and output the result as a signal designated as code Tj (which in this embodiment can refer to a chip junction temperature, but can also include any other temperature to be measured in a given application). This temperature measurement is just one example of any other measurement that the analog-to-digital converter 63 can perform. Such temperature measurements, or other measurements, can be used, for example, to adjust / calibrate the magnetic field sensor.

[0060] Other embodiments can alternatively or additionally measure (directly or indirectly) load-dependent channels, chip cracks with resistance loops, pressure, light, electric fields, internal or external (known) voltages, or any other physical property required by a specific application, e.g., for adjustment and / or calibration purposes, or to exploit the combined use of an analog-to-digital converter such as converter 63 in a system approach to measure any physical quantities related or unrelated to the magnetic field measurement. In some embodiments, a converter such as converter 63 can additionally or alternatively be used to perform a redundant magnetic field measurement in addition to the result of converter 411, using an additional Hall sensor in addition to the setup comprising Hall sensor 49 (e.g.,to provide a measurement at a certain distance from the Hall sensor 49, e.g. to measure a magnetic background field).

[0061] Furthermore, in some embodiments, a redundant magnetic field measurement can use a different measurement principle (e.g., using a magnetoresistive sensor – e.g., GMR, TMR, or xMR in general) instead of an additional Hall probe. Such a magnetoresistive sensor can again be connected to the analog-to-digital converter 63 via multiplexing switches. In some embodiments, this can also be used to improve the independence of the redundant measurement setup (different types of measurements: H-fields versus B-fields).

[0062] It should be noted that in other embodiments, additional or alternative Hall sensors with sensitivity in other directions (lateral or vertical Hall sensors) can be used, employing the same principles as described here. This also applies to Hall sensor 49.

[0063] The diagnostic functions listed above, individually or in combination, can improve the single-point disturbance metric for the device shown, as well as a latent disturbance metric for safety systems that require magnetic field sensors such as the Hall-effect sensor devices shown. As already mentioned, even if in the embodiment of Fig. 6. While a variety of different diagnostic functions are implemented in this embodiment and described above, in other embodiments only one or some of these functions may be implemented. For example, if reduced redundancy is sufficiently specified through safety analysis, both ADCs can even use the same reference voltage, thus eliminating the need for connection 610 and the corresponding multiple operation.

[0064] It should be mentioned that in certain applications it may be necessary to implement an even more diverse setup by using different techniques to implement the reference voltages, e.g., a bandgap-based principle versus a multiple-resistor-based principle (which may require additional adjustment), to name just two examples. The embodiment of Fig. The setup shown in section 6 provides a highly flexible structure for implementing a variety of different solutions.

[0065] The same principles can apply to the selection of analog-to-digital converters. For example, for the sake of diversity, different principles can be used for converters 411 and 63 in embodiments to improve robustness against common design disturbances (or even systemic disturbances during implementation). For economic reasons, it may not be desirable in some cases to use more than two converters, but if required, for example, for safety reasons, other embodiments can use additional converters instead of multiple inputs to converter 63 (e.g., for parallel measurements to reduce interference detection time). In other embodiments, channels (analog signals) that are used in the embodiment of Fig. 6. In some embodiments, the analog-to-digital converter 63 (such as the junction temperature channel 62) is converted by the converter 411 (using an additional multiplexer on its input). In general, the use of such multiplexers allows different quantities to be measured / converted in different operating phases of an analog-to-digital converter.

[0066] Next, regarding the Fig. 7-9 different modifications of the embodiment of Fig. 6. To avoid repetition, identical elements bear the same reference numerals, and only the differences or modifications compared to the embodiment of Fig. 6 are described in more detail.

[0067] In the embodiment of Fig. 6. The diagnosis can be performed, at least partially, outside the sensor device if a very high degree of diagnostic independence is required. For example, if signals c and d differ from each other by more than a threshold value, the evaluation can be carried out by an external unit. Similarly, if signals code Vbias and code Vref indicate an error, an evaluation can be performed by an external unit.

[0068] For example, in a case where the system already requires a second, physically separate sensor IC, the diagnostic and independence requirements can be reduced to implement a more economical single-sensor setup that is used twice in the system. A lower required safety level for a particular application as such may also allow for a reduction in independence requirements. In such cases, for example, the setup can be as in the embodiment of Fig. 6 shown can be further simplified, as in Fig. Shown 7-9.

[0069] In the embodiment of Fig. 7. The diagnostic evaluation only occurs within the sensor device shown. For example, if the sensor device is implemented on a single chip, this can enable on-chip analysis.

[0070] In the embodiment of Fig. 7 is instead of the control unit 611 from Fig. 6. A control unit 711 is provided. Furthermore, a control unit 74 is provided instead of the control unit 64.

[0071] Furthermore, in the embodiment of Fig. 7 a single mean-former 70 instead of the mean-formers 66, 67 of Fig. 6. The averaging unit 70 calculates a sum of the output signals of the analog-to-digital converter 411 for all four phases of a spinning current technique, or even an average over a large number of measurement cycles, and outputs this as signal e. Signal e therefore provides a measured value for the magnetic field measured by the sensor 49. Furthermore, the outputs for the four phases are provided for a control unit 711. The control unit 711 can perform functions such as those related to Fig. 6. For signals c and d, the control unit 711 can perform the following operations: it can calculate partial sums (for example, of the first and second phases and the third and fourth phases) and evaluate whether the difference between the partial sums exceeds a threshold value. Furthermore, the control unit 711 can combine the signals for the four phases to determine an offset, as described in section 6. Fig. 6 described, and evaluate the result. If the result shows no error, the control unit 711 can output an "OK" signal indicating that no fault was detected. In other embodiments, the additional or alternative control unit 711 can output an error signal indicating that a fault or disturbance was detected.

[0072] If the control unit 711 detects an error condition, it can control the averaging unit 70 to disable updates, thus freezing signal e, or it can control the averaging unit 70 to output a value of signal e indicating an error. In the latter case, the separate output of the "OK" signal can be omitted.

[0073] Furthermore, in the embodiment of Fig. The control unit 74 outputs the signals Code Vref and Code Vbias to determine whether a bias voltage provided by the power source 40 and a reference signal supplied to the analog-to-digital converter 411 are correct. In the case of no fault, an "OK" signal can be output, and / or in the case of a fault or disturbance, an error signal can be output. It should be noted that the signals output by the control units 74 and 711 (for example, the "OK" signal) can be provided at a common output, for example, using a logic gate that combines the signals.

[0074] Otherwise, the operation of the embodiment may be disrupted. Fig. 7 as for the embodiment of Fig. 6. It should be noted that in some embodiments only the control unit 711 or only the control unit 74 may be provided, and the respective other control unit may be provided as described in relation to Fig. 6 discusses work.

[0075] Fig. Figure 8 illustrates another embodiment. In the embodiment of Fig. 8 is compared to the embodiment of Fig. The analog-to-digital converter 411 is omitted, and the analog-to-digital converter 63 is additionally used to perform Hall voltage measurement using a spinning current technique and / or offset measurement. For this purpose, additional switches 83 are provided, enabling Hall voltage measurement by the analog-to-digital converter 63. A demultiplexer 82, coupled to the analog-to-digital converter 63, serves to output measured signals to appropriate output connections by closing switches 61, 83, 84, and 62. Measurement results from a spinning current technique (switches 83 are closed) are provided to an averaging unit 83, which provides the sum over all four phases or an average sum over a multitude of measurement cycles and outputs it as signal h. The signal h therefore provides a measured value for the magnetic field measured by the magnetic field sensor.

[0076] A control unit 80 serves to provide the diagnostic functions discussed above by evaluating the signals output by the spinning current scheme (for example, by providing partial sums as discussed above) in order to calculate the offset by evaluating the code Vbias signal obtained when the switches 61 are closed. Furthermore, in embodiments, the analog-to-digital converter 63 can measure a generated internal or external voltage via switches 84 (e.g., a divided supply voltage VDD / 4 as shown, or any other known voltage from the system). This can again improve the diagnostics of the converter and the reference 63 (especially if more than one voltage level can be measured) in some embodiments.

[0077] The control unit 80 also controls switches PH1-PH4, TSta-d, and switches 61, 83, 84, and 62. To perform this control, the control unit 80 is supplied by a counter 81, which counts from 1 to N. N in the embodiment of Fig. 8 can be 4 for four spinning current phases plus a number of additional measurement phases for diagnostic functions, for example a diagnosis with switches 61 closed to measure the bias current, or measurements with a fault current injected as previously described.

[0078] If no fault occurs, the control unit 80 can output an "OK" signal, and / or if a fault is detected, the control unit can output an error signal.

[0079] Fig. Figure 9 illustrates a magnetic field sensor device according to a further embodiment. The embodiment of Fig. 9 is to some extent a combination of the embodiments of Fig. 6 and Fig. 8. Similar to the embodiment of Fig. 8 is in the embodiment of Fig. 9 a single analog-to-digital converter 63 is used. Similar to the embodiment of Fig. 6 A control unit 92 controls the switching of the switches based on a PHTST enable signal for switches PH1-PH4 and TSTa-TSTd and based on a VTST enable signal for switches 61. Further similar to the embodiment of Fig. 6. The evaluation is carried out outside of the device shown. For example, the output signals relating to the four spinning current phases are provided by the demultiplexer 82 for a switch 90, which is controlled by the control unit 92, which provides the signals for a first averaging unit 91 and a second averaging unit 92. The function of the first and second averaging units 91 and 92 is the same as the function of the averaging units 66, 67 of Fig. 6, namely to provide two signals h, k, each representative of the partial sum over the output results of the individual spinning current phases.

[0080] Switch 90 can be controlled by control unit 80, for example to change the way the partial sums are calculated, as also previously mentioned in relation to Fig. 6 explained (for example, summing phases 1 and 2 to obtain signal h, and phases 3 and 4 to obtain signal k, or summing the signals from phases 1 and 4 to obtain signal h, and from phases 2 and 3 to obtain signal k).

[0081] Fig. Figure 9 therefore illustrates that features from different embodiments can be combined to form further embodiments, and other features from different embodiments can also be combined to form further embodiments.

[0082] With the diagnostic functions discussed, in some embodiments the provision of a secondary sensor for redundancy can be omitted while still maintaining a high level of functional safety. In other embodiments, the previously discussed magnetic field sensor devices can be combined with another magnetic field sensor device (either conventional or as described) to provide both redundancy and the previously discussed diagnostic functions.

[0083] Magnetic field sensor devices, as discussed above, can be used in an automotive environment, for example, but are not limited to this. An exemplary environment is in Fig. 10 illustrated.

[0084] A in Fig. The system shown in 10 comprises a magnetic field sensor device 101, which, as previously described, Fig. 1-9 discussed. The magnetic field sensor device 101, for example, is supplied with a clock signal clk and / or with supply voltages or reference voltages by a supply device 100. The supply device 100 can comprise any conventional circuit arrangement to provide supply voltages and / or clock signals. The supply device 100 can also provide supply voltages and clock signals for other devices of the system. Fig. Provide 10.

[0085] The system of Fig. 10 is controlled by an ECU (electronic control unit) system 102, for example, an ECU of a car. In alternative embodiments, the system can be controlled by any type of microcontroller, which may be integrated into the magnetic field sensor device 101 or provided outside of the magnetic field sensor device 101.

[0086] The ECU system 110 controls the magnetic field sensor device 101 via an interface 103. For example, the ECU system 102 can provide signals such as the VTST enable and PHTST enable signals discussed above in the case of external diagnostic control. Conversely, the ECU system 102 receives data from the magnetic field sensor device 101 via the interface 103 and optionally via a digital signal processor 104. In some embodiments, the digital signal processor 104 can provide an evaluation of the signals provided by the magnetic field sensor device 101 for diagnostic functions, for example, based on the signals c, d, code Vbias, and code Vref. Fig. 6. In other embodiments, such an evaluation can be carried out by the ECU system 102. In still other embodiments, for example, as with regard to Fig. 7 and Fig. As described in section 8, such an evaluation can be carried out internally in the magnetic field sensor device 101.

[0087] The system of Fig. 10 is merely an exemplary environment, and magnetic field sensor devices as described herein can generally be used in applications where a magnetic field is to be measured.

[0088] Fig. Figure 11 is a flowchart illustrating a method according to one embodiment. Even if the method is of Fig. Figure 11 illustrates a series of processes or events; however, the order in which these processes or events are shown and described should not be considered restrictive. For example, processes and events may be carried out in a different order compared to the sequence shown, and / or some of the processes or events may be carried out simultaneously, for example, using different parts of a circuit. The procedure of Fig. 11 can be implemented using any of the previously discussed magnetic field sensor devices, but is not limited to them.

[0089] At 110 in Fig. 11 The method includes providing a magnetic field sensor device. The magnetic field sensor device may include a magnetic field sensor associated with a plurality of switches. For example, the magnetic field sensor device may be a magnetic field sensor device as described above with respect to Fig. 1-9 have been discussed.

[0090] At 111, the switches of the magnetic field sensor device are controlled to provide a spinning current readout. At 112, fault information based on the spinning current readout is provided. For example, partial sums can be calculated and compared as explained above, and / or an offset can be calculated.

[0091] At 113, the switches are controlled to provide additional fault information. For example, switches can be controlled in addition to those controlled at 111 to inject a fault current and / or to allow measurement of a bias current or reference voltage, for example, as explained previously. It should be noted that in the embodiment of Fig. In some cases, either the 111 assigned operations or the 113 assigned operations may be omitted, with only a portion of the error information being provided.

[0092] The above embodiments serve only as examples and should not be considered restrictive.

Claims

[1] Device comprising: a magnetic field sensor (10; 24; 30; 49), a variety of switches (11; PH1-4; TST; 61, 68; 69) associated with the magnetic field sensor, and a control circuit (12; 611) configured to control at least some of the plurality of switches (11; PH1-4; TST; 61, 68; 69) to apply a spinning current scheme to the magnetic field sensor (10; 24; 30; 49), wherein the spinning current scheme comprises a plurality of phases in which different terminals of the magnetic field sensor (10; 24; 30; 49) are used for biasing and readout, to obtain a multitude of measurement signals according to the spinning current scheme from the magnetic field sensor (10; 24; 30; 49), to form a first mean of a first group of the multitude of measurement signals and to form a second mean of a second group of measurement signals different from the first group, and to provide at least one signal indicative of a disturbance based on a comparison of the first mean and the second mean. [2] Device according to claim 1, wherein the control circuit (12; 611) is configured to form at least two partial sums over readout results of the plurality of phases in order to provide the at least one signal. [3] Device according to claim 2, wherein the control circuit (12; 611) is configured to provide a signal indicating an error if a difference between two of the partial sums exceeds a predetermined threshold. [4] Device according to one of claims 1-3, wherein the control circuit (12; 611) is configured to obtain an offset based on readout results of the plurality of phases. [5] Device according to one of claims 1-4, wherein the control circuit (12; 611) is configured to control at least one of the plurality of switches (11; PH1-4; TST; 61, 68; 69) to inject a fault current into the magnetic field sensor (10; 24; 30; 49), and is further configured to evaluate the correct operation of providing the at least one signal indicative of a fault based on the injected fault current. [6] Device according to one of claims 1-5, wherein the control circuit (12; 611) is configured to control at least one of the plurality of switches (11; PH1-4; TST; 61, 68; 69) to measure at least one of a bias current and bias voltage that biases the magnetic field sensor (10; 24; 30; 49). [7] Device according to claim 6, comprising a first analog-to-digital converter (411) configured to measure an output of the magnetic field sensor (10; 24; 30; 49) that is representative of a magnetic field, and a second analog-to-digital converter (63) configured to measure the bias current or bias voltage. [8] Device according to claim 6, comprising an analog-to-digital converter (63), wherein the analog-to-digital converter is configured to measure an output signal of the magnetic field sensor (10; 24; 30; 49) that is indicative of a magnetic field, and is further configured to measure the bias current or bias voltage. [9] Device according to one of claims 6-8, wherein at least one analog-to-digital converter (63, 411) of the device is further configured to measure at least one further quantity. [10] Device according to one of claims 1-9, further comprising an output to provide at least one signal to another unit to enable the other unit to determine a possible disturbance. [11] Device according to any one of claims 1-10, wherein the device is an integrated device on a single chip. [12] Device according to one of claims 1-11, wherein the magnetic field sensor (10; 24; 30; 49) comprises a Hall sensor. [13] Magnetic field sensor device comprising: a magnetic field sensor (10; 24; 30; 49), wherein the magnetic field sensor comprises a plurality of connections, a bias source, at least an analog-to-digital converter (63), a variety of switches (11; PH1-4; TST; 61, 68; 69), and a control unit (12; 611), wherein the control unit is configured to control the plurality of switches (11; PH1-4; TST; 61, 68; 69) to selectively couple the bias source and the analog-to-digital converter (63) to the plurality of terminals during a plurality of phases, a summing circuit to provide at least two partial sums of outputs of the analog-to-digital converter in different phases of the plurality of phases, wherein the control unit (12; 611) is further configured to evaluate a difference between the plurality of partial sums and output an error signal if the difference exceeds a threshold. [14] Device according to claim 13, wherein the control unit (12; 611) is further configured to combine outputs of the analog-to-digital converter (63) at different phases to determine an offset of the device. [15] Procedure, encompassing: Providing a magnetic field sensor (10; 24; 30; 49), controlling switches (11; PH1-4; TST; 61, 68; 69) associated with the magnetic field sensor, wherein controlling the switches includes controlling at least some of the switches to provide a spinning current readout in a variety of phases to obtain a variety of measurement signals, Forming an initial average value based on an initial group of the numerous measurement signals, Forming a second mean value based on a second group of the multitude of measurement signals that differs from the first group, and Providing error information based on a comparison of the first mean and the second mean. [16] Method according to claim 15, wherein providing error information comprises calculating at least two partial sums over the spinning current readouts and evaluating a difference between the partial sums. [17] Method according to claim 15 or 16, wherein providing fault information includes calculating an offset based on the spinning current readouts. [18] Method according to one of claims 15-17, wherein controlling the switches (11; PH1-4; TST; 61, 68; 69) comprises controlling at least some of the switches for at least one of providing additional fault information, providing additional calibration measurements and providing additional diagnostic measurements.

Images