Current sensor chip with magnetic field sensor

Abstract

A current sensor chip that features: a first magnetic field sensor element (20) configured to detect a first analog sensor signal (V H ) to generate a magnetic field that is generated by a primary current (i) flowing through an external primary conductor (1). P ) is caused; an analog-to-digital converter (21) coupled to the first magnetic field sensor element (20) and configured to perform a conversion based on the first analog sensor signal (V) H ) a digital sensor signal (V DIG to generate; a digital signal processor (30) coupled to the analog-to-digital converter (21) to process the digital sensor signal (V DIG ) to receive, and which is trained to do so based on the digital sensor signal (V DIG ) and, based on calibration data stored in a memory for calibrating the current measurement, a corresponding current measurement signal that represents the primary current (iP ) represents, to determine; and an external output pin (CAL) coupled to the first magnetic field sensor element (20) to supply the output pin (CAL) with the first analog sensor signal (V) H ) or to supply an analog signal derived from it, which is derived from the first sensor signal (V H ) is derived by means of signal processing without quantization of analog signals, which contain information about the magnetic field caused by the primary current.

Description

TECHNICAL AREA

[0001] Exemplary embodiments of the present invention relate to the field of current measurement using magnetic field sensors. BACKGROUND

[0002] Non-contact current measurement can be achieved using a magnetic field sensor to measure the magnetic field generated by a current flowing through a primary conductor (hereinafter referred to as the primary current). The magnetic field generated by the primary current depends on the strength of the primary current. For example, a long, straight wire carrying a primary current i P The strength of the resulting magnetic field H at a distance d from the wire is directly proportional to the primary current i. P According to the Biot-Savart law, the magnitude of the magnetic field H is equal to H=i P / (2πd) when the wire is very long (theoretically infinitely long) compared to the distance d. In practice, a chip package containing the magnetic field sensor element (e.g., a Hall sensor) is placed close to the primary conductor. The chip package is also called a sensor package or current sensor package. The magnetic field sensor element (or simply the magnetic field sensor) contained within the chip package is therefore exposed to the magnetic field caused by the primary current, and the sensor signal provided by the magnetic field sensor element (usually a voltage signal) is proportional to the strength of the magnetic field and consequently also proportional to the primary current.

[0003] Conventional Hall effect sensors and magnetoresistive sensors are used for non-contact current measurement. Magnetoresistive sensors are often referred to as XMR sensors, a collective term encompassing anisotropic magnetoresistive (AMR), giant magnetoresistive (GMR), tunnel magnetoresistive (TMR), and colossal magnetoresistive (CMR) sensors. The sensor housing may also contain a signal processing circuit that receives the signal from the magnetic field sensing element (also called the sensor signal) and derives a measurement signal from the sensor signal, representing the primary current.

[0004] A measuring device for non-contact current measurement (also called a current sensor) typically includes a soft magnetic core or a flux concentrator to direct the magnetic field generated by the primary current onto the magnetic field sensing element. The soft magnetic core can also shield the magnetic field sensing element from interfering external magnetic fields that can cause measurement errors. However, the use of a soft magnetic core or flux concentrators can lead to undesirable effects due to the non-linear characteristic and hysteresis of the soft magnetic core. The core's hysteresis can result in a zero-point error in the current measurement. To avoid such problems, coreless current sensors have been developed. However, when using coreless current sensors, precise positioning of the magnetic field sensing element relative to the primary conductor is crucial for accurate current measurement.Consequently, the tolerances for assembling the current sensor must be relatively tight.

[0005] In general, the accuracy of a coreless magnetic current measurement is influenced by the geometry of the primary conductor (also known as the current rail) and its position relative to the magnetic field sensor element. To ensure precise relative positioning of the primary conductor and the magnetic field sensor element, they can be integrated into the same chip package (sensor package). This approach is used, for example, in Infineon's TLI4970 current sensor family (see, e.g., Infineon TLI4970-D050T4, Data Sheet, Rev. 1.0, November 21, 2014). In addition to a digital output, the TLI4970-D050T4 current sensor chip features an output pin that provides a (binary) overcurrent signal, indicating when the current through the primary conductor exceeds a configurable maximum allowable value.When using a current sensor with an integrated busbar, the primary conductor carrying the primary current (e.g., a wire, cable, busbar, etc.) must be disconnected (interrupted) to insert the chip package with the integrated busbar. In some applications, disconnecting the primary conductor is either undesirable or impossible. When using a primary conductor located entirely outside the chip package containing the magnetic field sensor element, the problem remains that the measured signal (representing the primary current) is highly dependent on the geometry of the primary conductor-chip package assembly without precise knowledge of the transfer characteristic (primary current to measurement signal) of the setup. Consequently, there is a general need for improved current sensors that allow for precise coreless and non-contact current measurement. The Melexis MLX91206 current sensor chip (see Melexis, MLX91206, Data Sheet, Rev. 10) addresses this need.042, Dec. 2013) is designed for printed circuit board mounting, with the primary conductor being a strip conductor that passes centrally under the current sensor chip along its axis of symmetry (longitudinal axis). The sensor output of the MLX91206 current sensor chip can be configured as an analog output or as a digital PWM output. SUMMARY

[0006] A current sensor chip is described below. According to one embodiment, the current sensor chip has a first magnetic field sensor element configured to generate a first analog sensor signal representing a magnetic field caused by a primary current flowing through an external primary conductor. The current sensor chip further includes an analog-to-digital converter coupled to the first magnetic field sensor element and configured to generate a digital sensor signal based on the first analog sensor signal. A digital signal processor is coupled to the analog-to-digital converter to receive the digital sensor signal and is configured to determine a corresponding current measurement signal, representing the primary current, based on the digital sensor signal and calibration parameters stored in memory.An external output pin of the current sensor chip is coupled to the first magnetic field sensor element to receive the first analog sensor signal or a signal derived from it by means of analog signal processing.

[0007] According to another embodiment, the current sensor chip comprises a first magnetic field sensor element configured to generate a first analog sensor signal in response to a magnetic field generated by a primary current flowing through an external primary conductor. The current sensor chip further comprises a second magnetic field sensor element configured to generate a second analog sensor signal in response to a magnetic field generated by the primary current flowing through the external primary conductor. An analog-to-digital converter is coupled to the second magnetic field sensor element and configured to generate a digital sensor signal based on the second analog sensor signal.A digital signal processor is coupled to the analog-to-digital converter to receive the digital sensor signal and is configured to determine a corresponding current measurement signal, representing the primary current, based on the digital sensor signal and calibration parameters stored in memory. An external output pin of the current sensor chip is coupled to the first magnetic field sensor element to receive the first analog sensor signal or an analog signal derived from it via analog signal processing.

[0008] Furthermore, a system for calibrating a current sensor chip is described here. According to one embodiment, the system comprises a current measurement arrangement which includes a current sensor chip and a primary conductor that is arranged adjacent to, but separate from, the current sensor chip. According to the present embodiment, the current sensor chip has a first magnetic field sensor element configured to generate a first analog sensor signal in response to a magnetic field caused by a primary current flowing through the primary conductor. The current sensor chip further includes a digital-to-analog converter coupled to the magnetic field sensor element or to a second magnetic field sensor element and configured to generate a digital sensor signal based on the first analog sensor signal or based on a second analog sensor signal.In the latter case, the second analog sensor signal is generated by the second magnetic field sensor element. Furthermore, the current sensor chip includes a memory for storing calibration parameters and a digital signal processor configured to use the calibration parameters stored in the memory and the digital sensor signal to determine a current measurement signal representing the primary current. An output pin of the current sensor chip is coupled to the first magnetic field sensor to receive the first analog sensor signal, or a sensor signal derived from it by analog signal processing, and to provide it as an analog output signal. The system also includes a test signal generator configured to generate a modulated test current, which is coupled to the primary conductor to inject the test current into the primary conductor as the primary current.Furthermore, the system includes a demodulator coupled to the output pin of the current sensor chip to receive the analog output signal. The demodulator is configured to demodulate the analog output signal and provide a measured value representing its strength. A controller is coupled to the current sensor chip to transfer calibration parameters, based on the measured value representing the strength of the analog output signal, to the current sensor chip's memory.

[0009] Furthermore, a method for calibrating a current sensor chip is described below. According to one embodiment, the method comprises: providing a current measurement arrangement comprising a current sensor chip and a primary conductor located adjacent to, but separate from, the current sensor chip; generating a modulated test current of a specific magnitude and injecting the modulated test current – ​​as the primary current – ​​into the primary conductor, thereby creating a magnetic field; and tapping an analog output signal from an external pin of the current sensor chip, wherein the analog output signal is an analog sensor signal or a signal derived therefrom by analog signal processing, and wherein the analog sensor signal is generated by a magnetic field sensor contained in the current sensor chip.Furthermore, the method includes demodulating the analog output signal to generate a measured value representing the magnitude of the analog output signal, determining calibration parameters based on the measured value, and storing the calibration parameters in a memory contained in the current sensor chip. BRIEF DESCRIPTION OF THE IMAGES

[0010] The invention can be better understood with reference to the following description and illustrations. The components shown in the figures are not necessarily to scale; rather, the emphasis is on illustrating the principles underlying the invention. Furthermore, identical reference numerals in the figures denote corresponding parts. Regarding the illustrations: Fig. Figure 1 is a block diagram showing an exemplary current sensor chip with an integrated primary conductor and digital output. Fig. Figure 2 is a block diagram illustrating an embodiment of a current sensor chip for use with an external primary conductor; the current sensor has a digital output, as well as an analog output which provides an analog sensor signal from an integrated Hall sensor for calibrating the current sensor. Fig. Figure 3 is a block diagram illustrating an example of a current sensor for use with an external primary conductor; the current sensor has an integrated Hall sensor as well as an integrated magnetoresistive sensor, wherein the sensor signal of the Hall sensor is digitized and fed to a digital output (after some signal processing), and wherein the sensor signal of the magnetoresistive sensor is fed to an analog output for calibration of the current sensor. Fig. Figure 4 is a block diagram that shows an example of the calibration process for the sensor. Fig. 3 arrangements used. Fig. Figure 5 is a block diagram that provides an example of the calibration process for the sensor. Fig. 2 arrangement used. Fig. Figure 6 is a flowchart that illustrates an exemplary procedure for calibrating a current sensor chip. DETAILED DESCRIPTION

[0011] The block diagram from Fig. Figure 1 illustrates a current sensor chip 2' with an integrated Hall sensor 20 and a primary conductor 1' (integrated busbar). The primary conductor 1' passes through the chip package of chip 2' and is therefore magnetically coupled to the Hall sensor 20. Since both the Hall sensor 20 and the primary conductor 1' are located in the same chip package, the position of the Hall sensor 20 relative to the primary conductor 1' is well-defined. Therefore, the strength of the magnetic field H (in the sensitive direction of the Hall sensor 20) at the position of the Hall sensor 20 can be determined very precisely. In general, the magnitude of the magnetic field H is proportional to the primary current i. P , that is, H=k·i P , where the constant k is between zero and (2πd) -1This is the theoretical limit for an infinitely long, straight primary conductor. A Hall sensor is typically formed by a plate-shaped conductor with defined length, width, and thickness; the sensor is supplied with a constant sensor current. The analog output voltage V H The Hall sensor 20 (Hall voltage) can be calculated as V H =A H ·i H ·µ0·H / t, where A H the Hall coefficient (in m 3 / C), µ0 the permeability constant, i H The constant sensor current and t the thickness of the Hall plate. As can be seen from the equation above, the sensor voltage is proportional to the strength of the magnetic field and the magnetic field is proportional to the primary current, where the proportionality factors depend only on parameters (k, A). H , i H , µ0, t) depend on factors that are either constant or depend on the design of the current sensor chip.

[0012] According to the example from Fig. 1. The sensor voltage V H The resulting digital sensor signal is digitized by means of an analog-to-digital converter 21. The resulting digital sensor signal is then connected to V. DIG designated. Of course, the sensor voltage V H The signal is amplified and filtered before being fed to the analog-to-digital converter 21. The amplifier and filter, the constant current source that supplies the sensor current i H The power supply circuits and other circuit components not necessary for the present discussion have been omitted from the figures to keep the illustration simple. The digital sensor signal is fed to a digital signal processor 30 (which is, for example, contained in a microcontroller). The digital signal processor (DSP) 30 can be configured to perform a function based on the digital sensor signal V. DIGand the aforementioned proportionality factors to calculate a digital measurement representing the primary current. Furthermore, the DSP can be configured to compensate for cross-sensitivities to other physical parameters such as temperature and chip strain. Information regarding temperature and chip strain can be obtained using dedicated sensors (in Fig. (1 not shown) are obtained, whose output signals can also be digitized and fed to the DSP. In particular, the reverberation coefficient A H temperature-dependent, and consequently the proportionality factor between the magnetic field H and the sensor voltage is also temperature-dependent. However, since the temperature characteristic of the Hall coefficient A HAs is known, cross-sensitivity with respect to temperature can be compensated for by measuring the temperature. In some embodiments, the mechanical stress (chip stress) in the chip (or strain) can be measured to also enable compensation of cross-sensitivity with respect to the chip voltage. The measured temperature and stress signals can be digitized and fed to the DSP 30. The measured temperature and voltage signals can be made available to an external device (e.g., by transmitting the measured values ​​as digital information via a communication interface, see below). Alternatively, the measured temperature and voltage signals can also be made available to an external device via a dedicated chip pin (not shown).

[0013] To use external electronic devices (e.g., an external control unit (in Fig. To communicate (not shown in Figure 1), the DSP 30 can have a communication interface circuit (or simply: communication interface) that allows the measured current values ​​to be transmitted digitally, e.g., via a data bus. In this example, the DSP 30 communicates via a Serial Peripheral Interface (SPI) bus. The current sensor is a bus slave and receives a chip select signal (CS) and a clock signal (SCLK) from a bus master (e.g., the external control unit) via dedicated chip pins and provides a serial data stream DOUT at an output pin of the sensor chip 2'. The DSP 30 can be any digital circuit suitable for processing digital signals. The DSP 30 can have a software-controlled processor (Central Processing Unit, CPU) as well as additional hard-wired digital and analog circuits. Alternatively, the DSP can be built from hard-wired digital circuits and optional analog circuits.For example, the DSP can be implemented using a Field Programmable Gate Array (FPGA), a Programmable Logic Array (PLA), or a Complex Programmable Logic Device (CPLD). Alternatively, the DSP can be contained in an application-specific integrated circuit (ASIC).

[0014] The block diagram from Fig. Figure 2 represents an exemplary current sensor chip 2 with an integrated Hall sensor 20, which is magnetically coupled to an external (i.e., located outside the chip package) primary conductor 1. In this context, "current sensor chip" refers to the packaged chip, which may contain one or more semiconductor dies with integrated circuits. The use of an external primary conductor enables non-contact current measurement without the need to disconnect the primary conductor 1 to insert an integrated current rail. Instead, the current sensor chip 2 is fixed to the primary conductor 1 (e.g., clamped onto it). The Hall sensor 20 contained in the sensor chip 2 may be identical or similar to that in the previous example, and consequently, reference is made to the description above. However, the proportionality factor (k = H / i) is P ) between the primary current i Pand the magnetic field H is not known a priori, since the position of the sensor chip 2 (and consequently the position of the Hall sensor 20) relative to the primary conductor is unknown at the time the sensor chip 2 is produced. Consequently, the proportionality factor depends on the application of the chip 2 and the geometry of the current measurement arrangement in which the sensor chip 2 is used.

[0015] As in the previous example, the sensor voltage V H the Hall sensor 20 is digitized (e.g. after amplification and filtering) and the resulting digital sensor signal V DIG is fed to the DSP 30. The digital signal processor (DSP) 30 can be configured to, based on the digital sensor signal V, DIG and to calculate a digital measurement value using the aforementioned proportionality factors, which represents the primary current i flowing through the external primary conductor 1 Prepresented. For this purpose, a calibrated proportionality factor k (k=H / i) can be used. P ) or K (K=V H / i P ) can be obtained using calibration data stored in memory 31. In this context, calibration data refers to any data that can be used to determine a calibrated value for the proportionality factor. For example, the calibrated proportionality factor can be stored in memory 31. Alternatively, the calibration data can include correction data that can be used to determine the calibrated value from a nominal value. Memory 31 can be connected to the DSP 30, which is configured to communicate with an external control unit (or any other external device) via a data bus or a point-to-point connection. The digital communication interface of the DSP 30 has already been described with reference to Fig. 1 described. In the present example, the DSP 30 can additionally receive an input data stream DIN (e.g. according to the SPI standard), which allows an external control unit (or any other external device) to send calibration data (and any other data) to the DSP, which stores the calibration data in memory 31 or updates previously stored calibration data.

[0016] To enable calibration of the device, a test current i TEST in the primary conductor as primary current (i P =i TEST The current sensor is typically designed to measure relatively high currents (e.g., 100 A or more). To keep the complexity of the setup used for calibration low, it is desirable to use a relatively low test current I. TEST (e.g., 1 A or less) to use. However, such a small test current I TESTa correspondingly small sensor signal V H This results in a low signal-to-noise ratio (SNR). In practice, the SNR can be less than 0 dB. For calibration purposes, the analog sensor signal V is used. H (Hall voltage) provided at an external chip pin located in the Fig. 2 is labelled CAL. This means that the output of the Hall sensor 20 can be directly connected to the chip pin CAL, or the sensor signal V H The signal can be pre-amplified (amplifier 22) while the amplifier output is connected to the chip pin CAL. The calibration procedure and setup will be described later with reference to the Fig. 4 and Fig. 5 discussed. In general, the analog sensor signal V Hor any signal derived from the analog signal by means of analog signal processing can be fed to the external chip pin CAL. In this context, "analog signal processing" can include any type of signal processing that does not include the quantization of analog signals (to obtain discrete-value signals) containing information about the magnetic field H. In practice, a buffer can be used to decouple the (pre-amplified) analog sensor signal from the output terminal (e.g., to allow driving a large capacitive load at the output terminal CAL). However, the buffer amplifier can also be considered part of the output stage of amplifier 22.

[0017] The example from Fig. 2 also includes a temperature sensor 26 and a chip stress sensor 27, which is configured to generate a sensor signal representing the mechanical stress in the semiconductor wafer in which the magnetic field sensor 20 is integrated. The temperature and chip stress information is provided to the DSP 30, which can then be configured to compensate for cross-sensitivities of the magnetic field sensor with respect to temperature and chip stress. Furthermore, the temperature and / or chip stress information can be provided to external devices, for example, via the aforementioned communication interface included in the DSP 30.

[0018] Fig. Figure 3 represents an alternative embodiment. The current sensor is made of Fig. 3 is similar to the current sensor from Fig. However, chip 2 has a second magnetic field sensor (XMR sensor 25) in addition to the Hall sensor 20 (the first magnetic field sensor). The first and second magnetic field sensors are positioned close to each other, so that they "see" practically the same magnetic field H or closely related field components of the magnetic field H. Even if they do not see exactly the same magnetic field—which may be the case—the magnetic field at the position of the first magnetic field sensor can be extrapolated based on the magnetic field at the second magnetic field sensor, since the positions of the two sensors relative to each other within the chip package are well-defined. For example, the Hall sensor may be sensitive to a vertical component of the magnetic field H, whereas the XMR sensor is sensitive to a horizontal component (assuming that the semiconductor wafer is placed in a horizontal plane).In this case, the horizontal and vertical field components would correlate, and one component could be derived from the other. In the present example, the output of the Hall sensor 20 is digitized and processed in the same way as in the previous example. Fig. 2. The digital communication interface (bus interface) is also the same as in the previous example. However, the analog sensor signal provided at the chip pin CAL is not received by the Hall sensor 20 (as in the example from Fig. 2 (is the case) is provided, but rather by the XMR sensor 25, which typically has a significantly higher sensitivity than the Hall sensor 20. Optionally, the sensor signal V can be DThe signal provided by the XMR sensor 25 is amplified (and, where applicable, buffered) before being fed to the chip pin CAL. Finally, it should be noted that vertical Hall sensors can also be used instead of lateral Hall sensors. Vertical Hall sensors, which are typically implemented in CMOS technology, are also sensitive to lateral (in-plane) field components (such as XMR sensors).

[0019] Fig. Figure 4 shows an arrangement for calibrating the current sensor. Fig. 3. The sensor chip that is in Fig. The part shown in 4 is identical to the sensor chip from Fig. 3. The arrangement of Fig. 4 additionally features a control unit 40 (e.g. a computer with suitable peripheral components), a test signal generator 41, and a lock-in amplifier 45, which operates synchronously with the test signal generator 41 (see Fig. 4, Signal SYN). The test signal generator is designed to produce a modulated test signal (a simple sine wave in this example) which is fed to the primary conductor and consequently generates a test current I. TEST This results in a current flowing through primary conductor 1. The test current i TEST is either known (i.e., through appropriate design of the test signal generator 41) or is measured separately (e.g., by means of a current-sensing resistor in the current path of the test current i). TEST The test current I TEST This results in a corresponding magnetic field at the position of the Hall sensor 20 and at the position of the XMR sensor 25. The XMR sensor 25 provides a corresponding analog signal V. D ready, which is provided at the external pin CAL of sensor chip 2. In the present example of a sinusoidal test current, the sensor signal V D likewise a sinusoidal waveform with the same frequency as the test current.

[0020] The analog sensor signal V D The signal is tapped at the external chip pin CAL and fed to a demodulator, which in this example is a lock-in amplifier. The lock-in amplifier 45 demodulates the sinusoidal sensor signal V. D , in order to measure its amplitude. The measured amplitude of the sensor signal V D is read by the calibration controller 40. For a given test current I TEST and based on the known sensor characteristic curve (characteristic curve V) D / H) of the XMR sensor 25, the controller 40 can calculate the magnitude of the magnetic field H at the position of the magnetic field sensors 20, 25; and based on the magnetic field H, the controller can also calculate the (calibrated) proportionality factor k (k=H / i P) for the Hall sensor. The proportionality factor k obtained in this way can be sent to the DSP 30 via the digital bus interface (serial data stream DIN) and stored – as calibration data – in the memory 31 of the sensor chip. The stored calibration data can then be used in later measurements based on the sensor signal V provided by the Hall sensor 20. H are based on, are used.

[0021] Fig. 5 presents an arrangement for calibrating the current sensor. Fig. 2. The arrangement is essentially the same as in the previous example according to Fig. 4. To avoid repetition, the above description of the Fig. 4 referred. Fig. However, section 5 illustrates how the test current I TESTThe primary conductor 1 is supplied via galvanic isolation. In the present example, the galvanic isolation is implemented by the decoupling capacitors C1 and C2, which are connected between a first output of the test signal generator 41 and one end of the external primary conductor 1, and between a second terminal of the test signal generator 41 and the other end of the external primary conductor 1, respectively. As an illustrative example, we assume a capacitance of 470 nF for each of the capacitors C1 and C2, and a frequency f. TEST of the test current I TEST from 10 kHz onwards. The impedance Z of the series connection of capacitors C1 and C2 is therefore (2πC1) -1 +(2πC2) -1 and consequently Z = 67.73 Ω (the resistance of the primary conductor is assumed to be negligible). Further assuming that the test signal generator 41 produces an AC voltage signal V TEST with a frequency f TESTand an amplitude of 5 V is generated (applied to the series circuit of capacitor C1, primary conductor 1 and capacitor C2), resulting in a test current I TEST by V TEST / Z with an amplitude of 73.83 mA. Further assuming that a primary current i is present during the operation of the current sensor. P A magnetic field H of 20 mT is generated by a current of 100 A at position 20 of the Hall sensor, and the test current I causes TEST a magnetic field of 14.77 µT, which is comparatively low, but can be easily measured using the lock-in amplifier 45. For very small test currents i TEST would the current sensor be off Fig. 3 and Fig. 4 easier to calibrate, since the XMR sensor 25 used for calibration is usually more sensitive than the Hall sensor 20.

[0022] In the previous examples, a lock-in amplifier 45 was used to demodulate a sinusoidal test current. However, other modulation / demodulation schemes can also be used to generate a modulated test current for calibrating the sensor chip 2 (see Fig. 2 and Fig. 3) an integrated current sensor can be used. Alternatively, spread spectrum modulation techniques can be used, where the test current is modulated, for example, with a pseudo-random spreading sequence (as can be done when using Direct Sequence Spread Spectrum (DSSS) modulation). The resulting sensor signal V H (or V H ') on the chip pin CAL will also be modulated with the spreading sequence and the demodulator 45 can determine the amplitude of the sensor signal V HDemodulation allows detection even at extremely low signal-to-noise ratios. Using spread spectrum techniques to modulate the test current and demodulate the resulting (pre-amplified) analog sensor signal involves "distributing" the test current signal over a continuous frequency range of a defined bandwidth, which can correspond to the bandwidth specified for current measurements on the current sensor chip. When using test currents with a single frequency (i.e., modulated with a sinusoidal carrier), the resulting calibration data can be frequency-dependent due to the occurrence of eddy currents. Therefore, using a test current with a defined bandwidth corresponding to the (analog) bandwidth of the current sensor chip can be more "realistic" and provide better calibration data.

[0023] Of course, the capacitive coupling can also be implemented using the decoupling capacitors C1 and C2 in the arrangement shown. Fig. 4. Furthermore, it should be noted that the connection between the controller 40 (e.g., a personal computer) and the demodulator 45 (e.g., a lock-in amplifier) ​​does not necessarily have to be a physical signal connection. A human operator can measure the current value of the sensor signal amplitude V. TH , as supplied by the demodulator 45, into the controller 40. Likewise, the connection between the controller 40 and the test signal generator is not necessarily a physical signal connection. However, the information about the test current i should be TEST(Amplitude) for control 40 will be available. It should be noted that in applications where galvanic isolation is not required, each of the capacitors C1 and C2 can be omitted or replaced by a resistor, a current source, or another suitable circuit arrangement.

[0024] Fig. Figure 6 is a flowchart illustrating an exemplary procedure for calibrating a current sensor chip, as described in Fig. 2 or Fig. Figure 3 shows a current measurement arrangement. According to the illustrated example, a current measurement arrangement is provided which includes a current sensor chip 2 (see e.g. Fig. 2 or Fig. 3), and has a primary conductor 1 that is adjacent to, but separate from, the current sensor chip 2 (see Fig. 6, Step 61). That is, the primary conductor 1 can be mechanically connected to the current sensor chip 2, but is located outside the (enclosed) current sensor chip 2 (is not integrated into it). A modulated test current I TEST is generated and fed as primary current into the primary conductor 1, thereby creating a magnetic field H (see Fig. 6, Step 62). The test current has a specific (preset) value. An analog output signal (see e.g. Fig. 4, Signal V D , or Fig. 5, Signal V H ') is tapped from an external pin CAL of the current sensor chip 2 (see Fig. 6, Step 63). As with reference to the Fig. As explained in sections 2 to 5, the analog output signal is either the analog sensor signal (signal V). H or V D) of the magnetic field sensor (Hall sensor 20 or XML sensor 25) contained in the current sensor chip 2, or derived from this analog sensor signal by means of analog signal processing (e.g. as signal V) H ' in the example from Fig. 5) The analog output signal is demodulated to produce a measured value that represents the magnitude of the analog output signal (see Fig. 6, step 64). In the example from Fig. 5 is the magnitude of the amplified Hall sensor signal V H 'Measured using a lock-in amplifier as demodulator 45. Based on the measured value, which represents the magnitude of the analog output signal, calibration parameters are determined (see Fig. 6, step 65), for example by calculation using a mathematical model of the current measurement arrangement. The calibration parameters are then stored in memory 31, which is contained in the current sensor chip 2 (see Fig.6, step 66).

[0025] The mathematical model of the current measurement arrangement can, as mentioned above, include the cross-sensitivities of the magnetic field sensor(s) with respect to temperature and / or chip voltage. Measured voltage (stress) and temperature values ​​can be made available to the controller 40 or other external devices, e.g., via a serial bus communication interface, as explained above. Accordingly, the calibration parameters can be calculated based on the measured value, which represents the strength of the analog output signal (e.g., V). H ') represents the known strength of the modulated test current i TEST as well as being based on a measured temperature of the current sensor chip and / or a measured chip voltage (i.e., a signal representing the mechanical stress in the semiconductor chip in which the magnetic field sensor is integrated).

[0026] While various embodiments of the invention have been described, it will be obvious to those skilled in the art that many further embodiments are possible within the scope of the invention. Therefore, the invention shall be limited except as set forth in the appended claims and their equivalents. With regard to the various functions performed by the components or structures (assemblies, devices, circuits, systems, etc.) described above, unless otherwise specified, the designations (including references to a “means”) used to describe such components shall also correspond to any other component or structure that performs the specified function of the described component (i.e.,which is functionally equivalent), even if it is not structurally equivalent to the disclosed structure which performs the function in the exemplary embodiments of the invention presented here.

Claims

[1] A current sensor chip that features: a first magnetic field sensor element (20) configured to detect a first analog sensor signal (V H ) to generate a magnetic field that is generated by a primary current (i) flowing through an external primary conductor (1). P ) is caused; an analog-to-digital converter (21) coupled to the first magnetic field sensor element (20) and configured to perform a conversion based on the first analog sensor signal (V) H ) a digital sensor signal (V DIG to generate; a digital signal processor (30) coupled to the analog-to-digital converter (21) to process the digital sensor signal (V DIG ) to receive, and which is trained to do so based on the digital sensor signal (V DIG ) and, based on calibration data stored in a memory for calibrating the current measurement, a corresponding current measurement signal that represents the primary current (iP ) represents, to determine; and an external output pin (CAL) coupled to the first magnetic field sensor element (20) to supply the output pin (CAL) with the first analog sensor signal (V) H ) or to supply an analog signal derived from it, which is derived from the first sensor signal (V H ) is derived by means of signal processing without quantization of analog signals which contain information about the magnetic field caused by the primary current. [2] The current sensor chip according to claim 1, wherein the first magnetic field sensor element (20) is a Hall sensor or a magnetoresistive sensor. [3] The current sensor chip according to claim 1 or 2, comprising at least one of the following components: a temperature sensor (26) configured to generate a temperature sensor signal, wherein the temperature sensor signal is made available to the digital signal processor (30) and / or an external device; a chip voltage sensor (27) configured to generate a voltage signal, wherein the voltage signal is provided to the digital signal processor (30) and / or an external device. [4] The current sensor chip according to any one of claims 1 to 3, further comprising: a communication interface circuit connected to the digital signal processor (30), wherein the digital signal processor (30) is configured to communicate with external devices via the communication interface circuit. [5] The current sensor chip according to one of claims 1 to 4, wherein the digital signal processor (30) is configured to receive data via the communication interface circuit and to store the received data as calibration data (k) in the memory (31). [6] A current sensor chip that features: a first magnetic field sensor element (25) configured to detect a first analog sensor signal (V D ) in response to a magnetic field generated by a primary current (i) flowing through an external primary conductor (1) P ) is caused; a second magnetic field sensor element (20) configured to receive a second analog sensor signal (V H ) in response to a magnetic field generated by the primary current (i) flowing through the external primary conductor (1) P ) is caused; an analog-to-digital converter (21) coupled to the second magnetic field sensor element (20) and configured to perform a conversion based on the second analog sensor signal (V) D ) a digital sensor signal (V DIG to generate; a digital signal processor (30) coupled to the analog-to-digital converter (21) to process the digital sensor signal (V DIG) to receive, and which is trained to do so based on the digital sensor signal (V DIG ) and, based on calibration data stored in a memory for calibrating the current measurement, a corresponding primary current (i P ) to determine the representing current measurement signal; and an external output pin (CAL) coupled to the first magnetic field sensor element (25) to provide the first analog sensor signal (V) to the output pin (CAL). D ) or to supply an analog signal derived from it, which is derived from the first sensor signal (V H ) is derived by means of signal processing without quantization of analog signals which contain information about the magnetic field caused by the primary current. [7] The current sensor chip according to claim 6, wherein the first magnetic field sensor element (25) is a Hall sensor or a magnetoresistive sensor. [8] The current sensor chip according to claim 6 or 7, further comprising at least one of the following components: a temperature sensor (26) designed to provide a temperature signal to the digital signal processor (30); a chip voltage sensor (27) which is configured to provide a chip voltage signal to the digital signal processor (30). [9] The current sensor chip according to any one of claims 6 to 8, further comprising: a communication interface circuit connected to a digital signal processor (30), wherein the digital signal processor (30) is configured to communicate digitally with an external device via the communication interface circuit. [10] The current sensor chip according to one of claims 6 to 9, wherein the digital signal processor (30) is configured to receive data via the communication interface circuit and to store the received data as calibration data (k) in the memory (31). [11] A system for calibrating a current sensor chip; the system comprises: a current measurement arrangement comprising a current sensor chip (2) and a primary conductor (1) which is arranged adjacent to but separate from the current sensor chip (2); the current sensor chip (2) comprises: a first magnetic field sensor element (20; 25) configured to detect a first analog sensor signal (V H ; V D ) in response to a magnetic field generated by a primary current (i) flowing through the primary conductor (1) P ) is caused; a digital-to-analog converter (21) coupled to the first magnetic field sensor element (20; 25) or a second magnetic field sensor element (20) and configured to convert a digital sensor signal (V DIG ) based on the first analog signal (V H ; V D ) or based on a second analog sensor signal (V H ) to generate which is generated by the second magnetic field sensor element (20); a memory (31) for storing calibration parameters; a digital signal processor (30) designed to use the calibration parameters stored in the memory (31) and the digital sensor signal (V) DIG ) to determine a current measurement signal which represents the primary current (i P ) represents; an output pin (CAL) that is coupled to the first magnetic field sensor (20; 25) to provide the first analog sensor signal (V) to the output pin (CAL). H ; V D) or to supply an analog signal derived from it and provide it as an analog output signal, wherein the derived analog signal is derived from the first sensor signal (V H ) is derived by means of signal processing without quantization of analog signals which contain information about the magnetic field caused by the primary current; a test signal generator (41) designed to produce a modulated test current (I TEST ) to provide, wherein the test signal generator is coupled to the primary conductor (1) to supply the test current (I TEST ) as primary current (i P ) to feed into the primary conductor (1); a demodulator (45) coupled to the output pin (CAL) of the current sensor chip to convert the analog output signal (V H') to receive, wherein the demodulator (45) is configured to demodulate the analog output signal and provide a measurement value representing the strength of the analog output signal; a controller (40) coupled to the current sensor chip (2) to provide calibration parameters (k) based on the strength of the first analog sensor signal (V) H ; V D ) representing measured value, to be transferred to the memory (31) of the current sensor chip (2). [12] The system according to claim 11, wherein the demodulator (45) and the test signal generator (41) are synchronized and the demodulator (45) is configured to produce the analog output signal (V H ') synchronous with the modulated test current (I TEST ) to demodulate. [13] The system according to claim 11 or 12, wherein the controller receives the calibration parameters (k) by input from an operator. [14] The system according to claim 11 or 12, wherein the controller (40) is configured to calculate the calibration parameters (k) based on input data received from an operator. [15] The system according to claim 11 or 12, wherein the controller (40) is coupled to the demodulator (45) to receive data representing the measured value, which in turn represents the strength of the first analog output signal, and wherein the controller (40) is configured to calculate the calibration parameters (k) based on data received from the demodulator (45). [16] The system according to any one of claims 11 to 15, where the modulated test current (I TEST ) exhibits a sinusoidal waveform and a specific strength, as well as a specific test frequency, and wherein the demodulator (45) is a lock-in amplifier designed to reduce the analog output signal (V H') to demodulate by mixing with a sinusoidal demodulation signal that has the test frequency. [17] The system according to any one of claims 11 to 16, where the modulated test signal (i TEST )v mit a spreading sequence is modulated according to a DSSS modulation technique, and wherein the demodulator (45) is a DSSS demodulator designed to demodulate signals that have been modulated according to a DSSS modulation technique. [18] A method for calibrating a current sensor chip, the method exhibits: Providing a current measurement arrangement comprising a current sensor chip (2) and a primary conductor (1) arranged adjacent to, but separate from, the current sensor chip (2); Generating a modulated test current (I TEST ) with a specific strength and injection of the modulated test current (I TEST ) as primary current (i P) into the primary conductor (1), thereby creating a magnetic field; Tapping an analog output signal at an external pin (CAL) of the current sensor chip (2), wherein the analog output signal is an analog sensor signal (V H , V D ) or a signal derived therefrom, where the analog sensor signal (V H , V D ) is generated by a magnetic field sensor (20, 25) contained in the current sensor chip (2) and wherein the derived analog signal is derived from the first sensor signal (V H ) is derived by means of signal processing without quantization of analog signals which contain information about the magnetic field caused by the primary current; Demodulating the analog output signal to generate a measured value that represents the strength of the analog output signal (V). H , V D ) represents; Determining calibration parameters (7) based on the measured values; Storing the calibration parameters in a memory (31) contained in the current sensor chip (2). [19] The method according to claim 18, comprising determining calibration parameters: Calculating the calibration parameters based on the measured value that represents the strength of the analog output signal (V). H ') represents, and the strength of the modulated test current (i TEST ). [20] The method according to claim 18, comprising determining calibration parameters: Calculating calibration parameters (k) based on the measured value that determines the strength of the analog output signal (V) H ') represents the strength of the modulated test current (I TEST ) and a measured temperature of the current sensor chip. [21] The method according to claim 18, comprising determining calibration parameters: Calculating calibration parameters (k) based on the measured value that determines the strength of the analog output signal (V) H ') represents the strength of the modulated test current (I TEST ) and a measured mechanical stress of the current sensor chip.

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