Sensors and sensor systems with analog output

Abstract

The invention relates to a sensor with analog output and a sensor system. A sensor comprises: at least one sensor element (111), the sensor element (111) being configured to measure an external parameter and output one or more results representing the external parameter; an output buffer (113), the output buffer (113) being configured to receive one or more results or processed versions thereof, and to apply an analog signal representing the result or a time-multiplexed sequence of analog signals representing a plurality of results on a sensor terminal (114), and to determine whether a trigger signal matches an ID of the sensor, and to enable the output buffer (113) during a predetermined period when the trigger signal matches the ID of the sensor.

Description

Technical Field

[0001] The present invention relates to the field of sensors. More specifically, the present invention relates to a sensor with analog output and a sensor system comprising a plurality of such sensors. Background Art

[0002] In automotive applications, multiple sensors are needed to measure multiple external parameters. In electronics in general, and more specifically in automotive applications, there is a constant need to optimize electronics in terms of complexity, cost, and safety. To simplify the required wiring, these sensors often transmit data via a digital bus. Examples of this are given in the following paragraphs.

[0003] In a sensor system, different sensors can be placed in parallel to enable multiple measurements of external parameters. These external parameters can be the same or different from each other.

[0004] The measured information is usually transmitted to a central system via a digital bus. In automotive applications, such a system is often called an electronic control unit. The main electronic control unit (ECU) will receive the measurement data from the different sensors.

[0005] In this sensor system, multiple slave devices (digital sensors) are connected to the same digital bus. To obtain information, the ECU transmits a read command over the digital bus, addressing one of the digital sensors.

[0006] On the sensor side, all sensors perform conversion operations. Therefore, they measure external parameters (such as physical quantities) and convert them into digital values. When the sensor receives a read command from the ECU, the sensor transmits the acquired digital value through the same digital bus.

[0007] Even though such sensor systems including digital buses over which sensor data is communicated have improved in terms of reducing wiring, there is still a need to reduce the complexity of sensors and sensor systems including such sensors. Summary of the invention

[0008] It is an object of embodiments of the present invention to provide a good sensor and a sensor system comprising a plurality of such sensors.

[0009] In a first aspect, an embodiment of the present invention relates to a sensor. The sensor includes at least one sensor element configured to measure an external parameter and output one or more results representing the external parameter. The sensor includes an output buffer configured to receive one or more results or processed versions thereof and apply an analog signal representing the result to a sensor terminal, or, in the case of more than one result, a time-multiplexed sequence of analog signals representing the result. In addition, the sensor also includes a control circuit configured to obtain a sensor ID (e.g., from an internal memory) and receive a trigger signal (e.g., from an external controller that applies the trigger signal to a sensor terminal or a power supply terminal). The control circuit is configured to determine whether the trigger signal matches the sensor ID, and to enable the output buffer within a predetermined period when the trigger signal matches the sensor ID.

[0010] An advantage of embodiments of the present invention is that the sensor terminals of multiple sensors with different IDs can be connected together without conflicting analog output buffers. This is achieved by enabling the output buffers during a predetermined period when the trigger signal matches the sensor's ID.

[0011] In an embodiment of the present invention, the control circuit is configured to determine whether the trigger signal matches the ID of the sensor by comparing the duration of the trigger signal and the ID.

[0012] In an embodiment of the present invention, the control circuit is configured to determine whether the trigger signal matches the ID of the sensor by comparing the number of pulses of the trigger signal and the ID.

[0013] In an embodiment of the present invention, the control circuit is configured to determine whether the trigger signal matches the ID of the sensor by counting the trigger signal to obtain a count number and comparing the count number with the ID.

[0014] In an embodiment of the invention, the sensor comprises a signal processing circuit configured to perform analog processing on the results of the sensor element before transmitting them directly or indirectly to an output buffer.

[0015] In an embodiment of the present invention, the control circuit is configured to enable the signal processing circuit when the trigger signal matches the ID of the sensor. In an embodiment of the present invention, all sensors can be triggered to perform measurements before checking whether the ID matches. In this case, each sensor is configured to enable the signal processing circuit when the trigger signal is received.

[0016] In an embodiment of the invention, the control circuit is configured to trigger the sensor element to measure the external parameter when a trigger signal is received and / or when the trigger signal matches an ID of the sensor.

[0017] In an embodiment of the present invention, the sensor includes a digital-to-analog converter and an analog-to-digital converter. In such an embodiment, the analog-to-digital converter can be configured to digitize the result of the sensor element and pass the digitized result to the control circuit. The control circuit can be configured to process the digitized result and pass the processed digitized result to the digital-to-analog converter, and the output of the digital-to-analog converter is directly or indirectly connected to the output buffer.

[0018] In an embodiment of the present invention, the control circuit is configured to obtain a trigger signal from the sensor terminal.

[0019] In an embodiment of the present invention, the sensor comprises a power terminal for connecting a power source for supplying power to the sensor.

[0020] In an embodiment of the invention, the control circuit is configured to obtain a trigger signal from one or both of the power supply terminals.

[0021] In a second aspect, embodiments of the present invention relate to a sensor system comprising a plurality of sensors according to embodiments of the present invention.

[0022] In addition, the sensor system further comprises an electronic control unit and a trigger circuit electrically connected to the control circuits of the plurality of sensors.

[0023] Additionally, the sensor system includes an analog input electrically connected to the output buffers of the plurality of sensors.

[0024] The trigger circuit is configured to generate a trigger signal for one or more sensors of the plurality of sensors. The analog input is configured to receive an analog signal from an output buffer of the sensor, wherein the analog signal is applied by the sensor whose trigger signal matches the ID of the sensor, and wherein the output buffers are electrically connected together.

[0025] In a sensor system according to an embodiment of the present invention, no two sensors output measurement results at the same time.

[0026] In an embodiment of the present invention, the electronic control unit comprises a power supply terminal for supplying power to the electronic control unit.

[0027] In an embodiment of the invention, the trigger circuit and the analog input are connected to the control circuit and the output buffer via a common electrical connection.

[0028] In an embodiment of the present invention, the trigger circuit is electrically connected to one or two power terminals of the electronic control unit, and one or two power terminals of the electronic control unit are electrically connected to power terminals of the sensor, so that the trigger signal can be transmitted from the trigger circuit to the sensor.

[0029] Particular and preferred aspects of the invention are set out in the accompanying independent and dependent claims. Features from the dependent claims may be combined with features of the independent claims and with features of other dependent claims as appropriate and not just as explicitly set out in a claim.

[0030] These and other aspects of the invention will be apparent from and elucidated with reference to the embodiment(s) described hereinafter. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 A schematic diagram of a sensor system according to an exemplary embodiment of the present invention is shown, wherein a trigger signal is received at sensor terminals.

[0032] Figure 2 A schematic diagram of a sensor system according to an embodiment of the invention is shown, wherein a trigger signal is received at a power supply terminal.

[0033] Figure 3 A supply voltage modulated with a trigger signal according to an embodiment of the present invention is shown.

[0034] Figure 4 A timing diagram is shown including a digital trigger signal containing an ID and a subsequent analog signal from a sensor with a matching ID in accordance with an embodiment of the present invention.

[0035] Figure 5 A timing diagram is shown according to an embodiment of the present invention including a digital trigger signal including an ID and a subsequent sequence of two time multiplexed analog signals from sensors with matching IDs.

[0036] Figure 6 A schematic diagram of a sensor according to an embodiment of the present invention is shown.

[0037] Figure 7 A schematic diagram of a sensor according to an embodiment of the present invention is shown, wherein measurement results are AD converted, processed and DA converted.

[0038] Figure 8 A schematic diagram of a sensor according to an embodiment of the present invention is shown, the sensor including a signal processing circuit.

[0039] Fig. 9A schematic diagram of a sensor system according to an embodiment of the present invention is shown, schematically illustrating an exemplary analog input circuit and an exemplary trigger circuit of an ECU.

[0040] Fig.10 An exemplary flow chart of a method implemented by a control circuit of a sensor according to an embodiment of the present invention is shown.

[0041] Any reference signs in the claims should not be construed as limiting the scope.The same reference signs in different drawings refer to the same or similar elements. DETAILED DESCRIPTION

[0042] The present invention will be described with respect to specific embodiments and with reference to certain drawings, but the invention is not limited thereto but only by the claims. The drawings described are schematic and non-limiting only. In the drawings, for illustrative purposes, the dimensions of some of the elements may be exaggerated and not drawn to scale. The dimensions and relative dimensions do not correspond to actual reductions to the implementation of the invention.

[0043] It is to be noted that the term "comprising" used in the claims should not be interpreted as being limited to the means listed thereafter; it does not exclude other elements or steps. Thus, the term should be interpreted as specifying the presence of the stated features, integers, steps or components as mentioned, but does not exclude the presence or addition of one or more other features, integers, steps or components, or groups thereof. Thus, the scope of the expression "a device comprising means "A and B" should not be limited to devices consisting only of components A and B. This means that for the present invention, the only relevant components of the device are A and B.

[0044] References throughout this specification to "one embodiment" or "an embodiment" mean that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the invention. Thus, the appearances of the phrases "in one embodiment" or "in an embodiment" in various places throughout this specification do not necessarily all refer to the same embodiment, but may refer to the same embodiment. Furthermore, in one or more embodiments, as will be apparent to one of ordinary skill in the art from this disclosure, the particular features, structures, or characteristics may be combined in any suitable manner.

[0045] Similarly, it should be understood that in the description of exemplary embodiments of the present invention, various features of the present invention are sometimes grouped together in a single embodiment, figure, or description thereof for the purpose of streamlining the present disclosure and assisting in understanding one or more of the various inventive aspects. However, this method of disclosure should not be interpreted as reflecting an intention that the claimed invention requires more features than those expressly recited in each claim. On the contrary, as reflected in the appended claims, inventive aspects reside in fewer features than all of the features of a single preceding disclosed embodiment. Therefore, the claims appended after the detailed description are hereby expressly incorporated into this detailed description, with each claim itself representing a separate embodiment of the present invention.

[0046] In addition, although some embodiments described herein include some features included in other embodiments but do not include other features included in other embodiments, as will be understood by those skilled in the art, the combination of features of different embodiments is intended to fall within the scope of the present invention and form different embodiments. For example, in the appended claims, any of the claimed embodiments can be used in any combination.

[0047] In the description provided herein, numerous specific details are set forth. However, it should be understood that embodiments of the present invention may be implemented without these specific details. In other examples, well-known methods, structures, and techniques are not shown in detail to avoid confusing the understanding of this description.

[0048] In a first aspect, embodiments of the present invention relate to a sensor 110 comprising at least one sensor element 111 configured to measure an external parameter. The sensor according to embodiments of the present invention is an analog sensor, which means that it has at least one analog output 114 (i.e., at least one sensor terminal 114 to which an analog signal is applied) for outputting the measured external parameter.

[0049] At least one sensor element is configured to output one or more results representing an external parameter. The sensor element may, for example, be configured to measure pressure, temperature, or magnetic field. The result representing the external parameter may be a quantity derived directly from the physical parameter, but not the physical parameter itself. For example, the result may indicate the position of the target, such as the rotation angle of a magnet or the linear position of a magnet, rather than the magnetic field strength. The result obtained may represent the magnetic field strength and may be derived / calculated from the magnetic field measured by the sensor element. In an embodiment of the present invention, the result may be an analog output signal. In an embodiment of the present invention, the result may represent an electric current.

[0050] The sensor 110 according to the embodiment of the present invention comprises power supply terminals 115 and 116 for connecting a power supply for supplying power to the sensor.

[0051] The sensor according to an embodiment of the present invention comprises an output buffer 113, which is configured to receive one or more results from at least one sensor element, or a processed version of these results, and to apply an analog signal representing the result or a time-multiplexed sequence of analog signals representing multiple results to at least one sensor terminal 114. The analog signal applied to the sensor terminal can be a DC signal, whose voltage or current represents the measured external parameter. In the case where a sequence of different measurement results needs to be transmitted, a time-multiplexed sequence of analog signals is applied to the sensor terminal. The resulting signal can be a DC signal whose voltage or current varies with the measured external parameter.

[0052] In an embodiment of the present invention referring to an output buffer, an electronic circuit is referred to that is configured to transmit an analog signal from an internal circuit of a sensor to an external circuit. The output buffer decouples the internal circuit of the sensor from an external circuit (e.g., an ECU) and / or protects the internal circuit of the sensor from the influence of the external circuit (e.g., an ECU). This is achieved by providing an impedance transformation between the internal circuit and the external circuit.

[0053] In an embodiment of the present invention, the output buffer may be an analog output buffer. Compared with a digital output buffer, an analog output buffer generally has a more linear input-output transfer characteristic.

[0054] In an embodiment of the present invention, the output buffer may have a unity gain (ie, a gain substantially equal to 1). The output buffer may be a voltage follower or a current follower.

[0055] In an embodiment of the present invention, the output buffer may also be referred to as a buffer amplifier. In an embodiment of the present invention, the gain may be, for example, comprised between 0.1 and 20, or 0.5 and 10, or 0.5 and 5, or 0.5 and 2.

[0056] The output buffer typically has a high input impedance and a low output impedance, which means that it can drive a higher current than the internal circuit connected upstream of the chip, for example to maintain the output level. The sensor 110 according to an embodiment of the present invention includes a control circuit 112, which is configured to obtain an identification of the sensor (also referred to as an ID, which can be, for example, an identification number that associates the sensor with a specific trigger signal, for example, with a pattern of the trigger signal). The ID can be hard-coded in the sensor (which can be implemented as a chip), or programmed (which can be obtained, for example, from a memory), or it can be determined based on external elements (e.g., a resistor, or one or more pins connected to VDD / GND / floating).

[0057] The control circuit 112 is configured to receive the trigger signal and determine whether the trigger signal matches the ID of the sensor. If the trigger signal matches the ID of the sensor, the control circuit can enable the output buffer 113 during a predetermined period.

[0058] This allows connecting different sensor terminals of different sensors to a central control unit (e.g. the electronic control unit of a car) via the same wires. It is not common to connect analog sensor terminals together, as this usually results in conflicts in the output buffers.

[0059] In an embodiment of the present invention, this is achieved by enabling the output buffer during a predetermined period after receiving a trigger signal that matches the sensor's ID. In an embodiment of the present invention, the sensor's output buffer is in a high-impedance mode (high-Z mode) outside of the predetermined period. This can be achieved in various ways, some examples of which are given below.

[0060] In an embodiment of the present invention, the output buffer may be a push-pull amplifier, such as a class B or AB amplifier. For example, the push-pull amplifier may include a pair of complementary MOSFETs (NMOS and PMOS). By blocking both transistors, the output node may be disabled, i.e., set to high impedance (floating). This may be achieved by connecting the gate of the NMOS to GND and the gate of the PMOS to VDD (e.g., using an additional switch). In this case, the output node of the buffer is isolated and the buffer does not drive the line.

[0061] In an embodiment of the present invention, the output buffer may include an additional transistor, such as a MOSFET, which acts like a switch at the output stage of the output buffer. The switch may, for example, be connected in series with its source and drain between the output of the buffer amplifier of the output buffer and the output terminal of the output buffer. A control signal on the gate of the switch may disconnect the output of the switch from the output terminal.

[0062] In a second aspect, embodiments of the present invention relate to a sensor system comprising a plurality of sensors and an electronic control unit 120. The electronic control unit comprises power supply terminals 125, 126, a trigger circuit 123 and an analog input 121.

[0063] The trigger circuit 123 is electrically connected to the control circuit 112 of the plurality of sensors 110. The analog input is electrically connected to the output buffers 113 of the plurality of sensors. The trigger circuit is configured to trigger the sensors to output a result such that only one output buffer is active at a time.

[0064] The analog input 121 of the ECU is configured to receive analog signals from the output buffers 113 of the sensors 110. All of these output buffers are connected together. In an embodiment of the present invention, this is possible because only one output buffer is enabled at a time. Therefore, in an embodiment of the present invention, the analog signal is only applied to the sensor terminals of the sensor whose trigger signal matches the sensor's ID.

[0065] In an embodiment of the present invention, multiple sensors may be addressed sequentially by the ECU. However, this is not strictly required. The ECU may decide to address any sensor when the ECU desires, as long as no two sensors have their output buffers enabled at the same time for addressing. The order in which the sensors are addressed may be a repeating order, however, this is also not strictly required. The ECU is also not required to address all sensors on the bus. It may address the same sensor multiple times, then another sensor, and so on. Furthermore, the periodicity does not need to be constant.

[0066] In an embodiment of the present invention, the trigger circuit may be a modulator configured to modulate a signal received by a control circuit of the sensor. The trigger circuit may include a regulator. A circuit such as a digital-to-analog converter may change the reference of the regulator, or may directly modulate the output.

[0067] In an embodiment of the present invention, the analog output of the sensor is connected with a digital output, which provides a trigger signal that encodes the ID. In such an embodiment, the trigger circuit 123 and the analog input 121 of the ECU are connected to the control circuit 112 of the sensor and the output buffer 113 of the sensor through a common electrical connection.

[0068] The analog input 121 of the ECU is configured to acquire a sensed physical quantity or a sequence of sensed physical quantities. The analog input may, for example, include an analog-to-digital converter.

[0069] Figure 1An example of a sensor system 100 according to an embodiment of the present invention is schematically shown. In this example, a trigger circuit 123 of an ECU 120 is electrically connected to a control circuit 112 via an output terminal 124a and a sensor terminal 114. In order not to overload the figure, the control circuit 112 is not shown in this figure. Figure 7 and Figure 8 In the exemplary schematic sensor diagram of FIG. , the control circuit 112 is drawn. Figure 1 In the example of , the analog input 121 of the ECU 120 is electrically connected to the output buffer 113 via the input terminal 124b and the sensor terminal 114. In this example, all sensor terminals are connected together to the same node, which is electrically connected to the node 124. Connections are made between the node 124 and the output terminal 124a and between the node 124 and the input terminal 124b. Optionally, the electrical connection between the node 124 and the input terminal 124b may include a filter. The filter may filter out noise or digital signals so that only analog signals are received at the input terminal 124b.

[0070] Each sensor 110 has a different ID.

[0071] The sensor is powered using power terminals 115 , 116 , and the ECU is powered through power terminals 125 , 126 .

[0072] Figure 2 FIG. 1 shows another example of a sensor system 100 according to an embodiment of the present invention. Figure 1 Unlike the example in Figure 2 In the exemplary embodiment of the present invention, the trigger signal is applied to the power supply terminal 125 of the ECU 120. The trigger signal may be an undervoltage or an overvoltage or a sequence of undervoltage and / or overvoltage. It may have a specific pattern, which may be a combination of the timing and / or amplitude and / or polarity of the trigger signal. The power supply VDD_S is also applied to the sensor 110. In this exemplary embodiment of the present invention, the power supply terminal 125 of the ECU is connected to the power supply terminal 115 of the sensor 110. In this case, the control circuit of the sensor 110 is configured to obtain the trigger signal from the power supply terminal 115.

[0073] exist Figure 3 An example of a supply voltage VDD_S is shown in FIG. 1 , which is related to the time modulated by a trigger signal. In this example, the duration of the trigger signal is used to match the trigger signal to the ID of the sensor. Dashed lines are drawn to show trigger signals with different durations.

[0074] In addition to using the duration of the trigger signal to match the trigger signal to the sensor's ID, the match can also be based on other trigger signal characteristics. For example, the number of pulses in the trigger signal can be used to match the trigger signal to the ID. The control circuit can also count the number of trigger signals it receives. Therefore, the counted number can correspond to the ID. The match between the trigger signal and the ID should be such that no two sensors can have their output buffers enabled at the same time.

[0075] Figure 4 A timing diagram is shown including a digital trigger signal including an ID during period t0, and a subsequent analog signal from a sensor with a matching ID during period t1. Since the signal of the measured value of the external parameter being measured is an analog signal, the analog signal must only have a duration long enough to determine the amplitude of the analog signal, which amplitude represents the external parameter being measured.

[0076] In an embodiment of the invention, the time multiplexed sequence of analog signals may be applied by the output buffer. In this case, the predefined period may be equal to or greater than the minimum duration of one analog signal multiplied by the number of analog signals transmitted after receiving the matching trigger signal.

[0077] For example, the required duration for an analog signal may be between 1 μs and 100 μs, or between 1 μs and 1 ms, such as 10 μs, or 20 μs. This is typically shorter than the time required to digitally transmit a digital value according to a digital protocol, since in this case the bits of the digital value must be transmitted sequentially and a complete digital frame and optionally a cyclic redundancy check (CRC) data frame need to be received so that the digital value can be decoded according to the digital protocol. Furthermore, a synchronization signal must be sent before the digital bits are sent. Furthermore, if an analog signal is obtained by a sensor element, an A / D conversion is not necessarily required to transmit the signal. Note that in some embodiments, the A / D conversion may be followed by a D / A conversion.

[0078] In case of a time multiplexed sequence of analog signals, the multiplexed signal may be, for example, a combination of:

[0079] -Analog voltage indicating sensor fault, e.g. a first level indicates good working condition, while a second level indicates a fault. Different levels can be used to report specific faults.

[0080] - Other sensor values ​​(e.g. temperature from a temperature sensor)

[0081] - Voltage reference used to scale the main measurement.

[0082] In an embodiment of the present invention, more than one analog value may be time multiplexed on the sensor terminal 114 . Figure 5 An example is shown in which a first analog value during period t1 is followed by a second analog value during period t2. In this example, each analog value has a duration of 20 μs. The first analog value may be, for example, a measured value of the Bz component of a Hall sensor, and the second analog value may be, for example, a measured value of the Bx,y component of a Hall sensor.

[0083] In some embodiments of the present invention, the analog signal may be a ratiometric output. The ratiometric output may be referenced to an external voltage, such as a power supply voltage.

[0084] In some embodiments of the invention, the analog output signal is referenced to the internal (voltage) reference of the sensor, i.e., it is not proportional to the power supply. In this case, the reference voltage as well as the additional analog value can be time multiplexed (see e.g. Figure 5 The internal voltage reference is usually lower than the supply voltage and is relatively insensitive to supply fluctuations. The advantage of this configuration is that the output signal is less sensitive to supply fluctuations.

[0085] Figure 6 A schematic diagram of a sensor 110 according to an embodiment of the present invention is shown. The sensor includes a control circuit 112 and an output buffer 113, the control circuit 112 is connected to a sensor terminal 114, and the output buffer 113 is also connected to the sensor terminal 114. In the sensor system 100 according to an embodiment of the present invention, the sensor terminal 114 is connected to the ECU 120. In this exemplary embodiment, the analog output of the output buffer and the digital signal from the ECU are both transmitted through the sensor terminal 114. The control circuit is configured to receive a trigger signal from the sensor terminal and to determine whether the trigger signal matches the ID of the sensor. By disabling the signal, the control circuit can put the output of the output buffer 113 in a high impedance state (high-Z). The control circuit is configured to enable the output buffer 113 during a predetermined period when the trigger signal matches the ID of the sensor. Figure 6 The sensor is powered via power supply terminals 115 and 116.

[0086] exist Figure 6In the embodiment, the sensor element 111 is directly connected to the output buffer 113. In such an embodiment, the measurement result of the sensor element can be an analog value transmitted to the output buffer 113. In addition to controlling the output buffer, the control circuit 112 can also be configured to control the sensor element so that the sensor element actively measures only when a matching trigger signal is received. For example, this can be done to reduce the power consumption of the sensor 110. The control circuit 112 can also be configured to control the sensor element so as to control the sensor element to obtain a measurement value when a trigger signal is received, such as accurately timing the moment of measuring a physical quantity. To this end, the control circuit is electrically connected to the sensor element. In Figure 6 In the example, the dashed line indicates that this is an optional connection. In other embodiments, the sensor element can measure continuously, for example. In this case, the sensor can be timed based on an internal clock that is asynchronous with respect to the ECU clock.

[0087] exist Figure 7 In the embodiment, a sensor element 111 configured to measure an external parameter is connected to an ADC 117. The output result of the sensor element is A / D converted by the ADC and can be further processed by a control circuit 112 connected to the output of the ADC 117. The control circuit 112 is connected to the input of a DAC 118, which is configured to perform D / A conversion on the processed result. The output of the DAC is connected to the input of an output buffer 113. Therefore, the analog value of the processed result is transmitted to the output buffer 113. As mentioned above, the output buffer is enabled only in a predetermined period and only when the trigger signal matches the ID of the sensor. The trigger signal is received by the control circuit through the connection with the sensor terminal 114.

[0088] In an embodiment of the present invention, the sensor 110 may include a signal processing circuit 119 configured to perform analog processing on the results of the sensor element 111 . Figure 8 An example of a sensor 110 according to an embodiment of the present invention is shown in the schematic diagram of FIG. The output of the sensor element 111 is connected to the input of the signal processing circuit 119. The output of the signal processing circuit is connected to the output buffer 113. In this example, the main signal processing chain is a full analog processing chain. In this example, the control circuit 112 does not process the results from the sensor element 111. The control circuit 112 is connected to the sensor terminal 114 for receiving a trigger signal. When a trigger signal with a matching ID is received, the control circuit 112 will enable the output buffer 113. Optionally, the control circuit can also enable the processing circuit 119, and this is only during a predetermined period after receiving the trigger signal with a matching ID. Therefore, compared with a sensor in which the processing circuit is continuously turned on, the power consumption of the sensor 110 can be reduced.

[0089] Fig. 9 A schematic diagram showing a possible implementation of analog input circuits 121 , 122 and a trigger circuit 123 of an ECU 120 according to an embodiment of the present invention is shown. Fig. 9 A schematic diagram of a sensor system 100 including a plurality of sensors 110 and an ECU 120 according to an embodiment of the present invention is also shown. Fig. 9 , a node 124 of the ECU 120 is connected to the sensor terminal 114 of the sensor. The node 124 is connected to the filter 122, and the filter 122 is connected to the analog input 121 of the ECU 120. The node 124 is also connected to the trigger circuit 123. In this example, the trigger circuit 123 includes a pulse modulator 123a, which is connected to the gate of the transistor 123b. The source and drain of the transistor 123b are connected between the ground and the node 124. Therefore, the trigger signal can be applied to the node 124.

[0090] Fig.10 An exemplary flow chart of a method implemented by a control circuit 112 of a sensor 110 according to an embodiment of the present invention is shown. The control circuit can be implemented, for example, as an application specific integrated circuit (ASIC) or a field programmable gate array (FPGA). After a power-on reset (POR), the control circuit 112 disables the analog output and reads the ID from the memory. The control circuit monitors the sensor terminals for a departure signal. Once a trigger signal is received, the control circuit can optionally trigger the sensor element and / or the signal processing circuit to obtain a measurement result. However, this is not strictly required. The sensor can also be configured to continuously measure an external parameter.

[0091] If the trigger signal does not match the sensor's ID, the control circuit continues to monitor the sensor terminals for the trigger signal.

[0092] If the trigger signal matches the sensor's ID, the analog output is enabled for a predetermined duration, after which the output is disabled again and the control circuit continues to monitor the sensor terminals for the trigger signal.

[0093] In a sensor system according to an embodiment of the present invention, all sensors on the bus can be configured to measure simultaneously. For example, the sensor can be configured to measure when a first trigger signal is received, or to measure when a specific trigger signal for triggering measurement is received. In an embodiment of the present invention, the specific trigger signal is independent of the sensor. For example, a specific trigger signal can address all sensors at the same time for measurement (the trigger signal can, for example, have a specific measurement ID that does not correspond to the sensor). Once the measurement is completed, when the trigger signal matches the ID of the sensor, the sensor will apply the simulation results one after another. In an embodiment of the present invention, the sensor is configured not to make a new measurement before transmitting all measurements, or to make a new measurement, but not to apply the value on the output. The advantage is that different analog sensors measure physical quantities at the same time (when a first trigger signal or a specific trigger signal only for measurement is received).

[0094] The sensor according to an embodiment of the present invention can be implemented as an integrated circuit. A plurality of these sensors can be implemented in a single package. These sensor terminals are connected to the output buffers of the sensors. The advantage of this is that the number of I / O pins can be reduced because the sensor terminals can be connected together with the analog output connections of the output buffers of different sensors.

Claims

1. A sensor (110), the sensor (110) comprising: Power supply terminals (115, 116), the power supply terminals (115, 116) being used to connect a power supply for supplying power to the sensor (110); at least one sensor element (111), the sensor element (111) being configured to measure an external parameter and output one or more results representative of the external parameter; an output buffer (113) configured to receive the one or more results or processed versions thereof and to apply an analog signal representing the result or a time-multiplexed sequence of analog signals representing the plurality of results to a sensor terminal (114); as well as A control circuit (112) is configured to obtain the ID of the sensor, and is characterized in that the control circuit (112) is further configured to receive a trigger signal and to enable the output buffer (113) during a predetermined period when the trigger signal matches the ID of the sensor.

2. The sensor (110) according to claim 1, wherein the control circuit (112) is configured to determine whether the trigger signal matches the ID of the sensor by comparing the duration of the trigger signal with the ID.

3. The sensor (110) according to claim 1, wherein: The control circuit (112) is configured to determine whether the trigger signal matches the ID of the sensor by comparing the number of pulses of the trigger signal with the ID.

4. The sensor (110) according to claim 1, wherein: The control circuit (112) is configured to obtain a count number by counting the trigger signal and determine whether the trigger signal matches the ID of the sensor by comparing the count number with the ID.

5. A sensor (110) according to any of the preceding claims, comprising a signal processing circuit (119) configured to perform analog processing on the results of the sensor element (111) before transmitting the results directly or indirectly to the output buffer (113).

6. The sensor (110) according to claim 5, wherein: The control circuit (112) is configured to enable the signal processing circuit (119) when the trigger signal is received and / or when the trigger signal matches the ID of the sensor.

7. The sensor (110) according to any one of the preceding claims, wherein: The control circuit is configured to trigger the sensor element (111) for measuring the external parameter when the trigger signal is received and / or when the trigger signal matches the ID of the sensor.

8. The sensor (110) according to any one of the preceding claims, wherein: The control circuit is configured to trigger the sensor element (111) for measuring an external parameter when receiving a specific trigger signal for triggering measurement.

9. The sensor (110) according to claim 8, wherein the specific trigger signal is independent of the sensor.

10. A sensor (110) according to any one of the preceding claims, the sensor (110) comprising a digital-to-analog converter (118) and an analog-to-digital converter (117), wherein the analog-to-digital converter (117) is configured to digitize the result of the sensor element (111) and transmit the digitized result to the control circuit (112), and wherein the control circuit (112) is configured to process the digitized result and transmit the processed digitized result to the digital-to-analog converter (118), and the output of the digital-to-analog converter is directly or indirectly connected to the output buffer (113).

11. The sensor (110) according to any one of the preceding claims, wherein The control circuit (112) is configured to obtain the trigger signal from the sensor terminal (114).

12. The sensor (110) according to any one of claims 1 to 10, wherein the control circuit (112) is configured to obtain the trigger signal from one or both of the power supply terminals (115, 116).

13. A sensor system (100), the sensor system (100) comprising: A plurality of sensors (110) according to any one of the preceding claims, and an electronic control unit (120), the electronic control unit (120) comprising power supply terminals (125, 126), a trigger circuit (123) electrically connected to a control circuit (112) of the plurality of sensors (110), and an analog input (121) electrically connected to an output buffer (113) of the plurality of sensors (110), wherein the trigger circuit (123) is configured to generate a trigger signal for one or more of the plurality of sensors (110), respectively, and wherein the analog input (121) is configured to receive an analog signal from the output buffer (113) of the sensor (110), wherein the analog signal is applied by the sensor (110) whose trigger signal matches the ID of the sensor, and wherein the output buffer (113) is electrically connected together.

14. The sensor system (100) of claim 13, wherein the sensor is dependent upon claim 11, and wherein the trigger circuit (123) and the analog input (121) are connected to the control circuit (112) and the output buffer (113) using a common electrical connection.

15. A sensor system (100) according to claim 13, wherein the sensor is dependent on claim 12, and wherein the trigger circuit (123) is electrically connected to the one or two power supply terminals (125, 126) of the electronic control unit (120), and wherein the one or two power supply terminals (125, 126) of the electronic control unit are electrically connected to the power supply terminals (115, 116) of the sensor (110), so that the trigger signal can be transmitted from the trigger circuit (123) to the sensor (110).

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