JP2018006893A - Abnormality detection device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an abnormality detection device capable of detecting abnormality of an AD conversion part with high accuracy without depending on an individual difference.SOLUTION: A comparison part 5 compares a converted value C1 obtained after an analog signal C is subjected to AD conversion by an AD conversion part 3, and an expectation value C0 being stored in a nonvolatile memory 6, and makes a determination that the AD conversion part 3 is normal when both coincide with each other, whereas makes a determination that the AD conversion part 3 is abnormal when both do not coincide with each other. In the nonvolatile memory 6, a value of an abnormal detection digital signal, which is obtainable by converting the abnormality detection analog signal C by the AD conversion part 3 at predetermined timing, is being stored as the expectation value C0.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an abnormality detection device, and more particularly to an abnormality detection device that detects an abnormality of an AD conversion unit.

  Conventionally, a technique for determining whether or not an AD conversion unit is abnormal is known. For example, in Japanese Patent Laid-Open No. 2014-49916 (Patent Document 1), an abnormality detection analog signal is input to an AD conversion unit, and the value of a digital signal after AD conversion of the abnormality detection analog signal is performed with a RAM. An apparatus that detects an abnormality of an AD conversion unit by comparing with an expected value stored in advance in (Random Access Memory) is disclosed.

JP 2014-49916 A

  It is difficult to manufacture an AD conversion unit having exactly the same characteristics due to various factors such as a member used, a manufacturing place, a manufacturing time, and a manufacturing method. However, the technique disclosed in Patent Document 1 does not take into account individual differences of the AD conversion unit with respect to the expected value stored in the RAM, and may not detect an abnormality of the AD conversion unit with high accuracy.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide an abnormality detection apparatus that can accurately detect an abnormality in an AD conversion unit regardless of individual differences.

  An abnormality detection device according to an aspect of the present invention includes a nonvolatile memory, an input unit, an AD conversion unit, and a comparison unit. The nonvolatile memory stores an expected value for abnormality detection. A plurality of analog signals including predetermined abnormality detection analog signals are input to the input unit. The AD conversion unit converts the analog signal input to the input unit into a digital signal. The comparison unit detects an abnormality in the AD conversion unit by comparing the value of the abnormality detection digital signal obtained by converting the abnormality detection analog signal by the AD conversion unit with an expected value. In the nonvolatile memory, the value of the abnormality detection digital signal when the abnormality detection analog signal is converted by the AD converter at a predetermined timing is stored as an expected value.

  According to this abnormality detection apparatus, the value of the abnormality detection digital signal when the analog signal for abnormality detection is converted by the AD conversion unit at a predetermined timing is stored in the nonvolatile memory as an expected value, and the comparison unit An abnormality of the AD conversion unit can be detected using the value. Therefore, the abnormality detection apparatus can detect the abnormality of the AD conversion unit using the expected value in consideration of the individual difference of the AD conversion unit to be determined, and thus the abnormality of the AD conversion unit can be accurately determined regardless of the individual difference. It can be detected well.

  Preferably, the abnormality detection device further includes a conversion power supply unit. The abnormality detection analog signal is generated from a reference voltage supplied by the conversion power supply unit.

  According to this abnormality detection device, the conversion power supply unit supplies a reference voltage to the AD conversion unit, and an abnormality detection analog signal is generated from the reference voltage. Therefore, the abnormality detection analog signal is the same as the reference voltage. It has temperature characteristics. Therefore, since the temperature characteristic of the analog signal for abnormality detection does not affect the abnormality detection of the AD conversion unit, the abnormality detection device can detect the abnormality of the AD conversion unit with high accuracy.

  Preferably, the abnormality detection device further includes a conversion power supply unit and a detection power supply unit. The conversion power supply unit supplies a reference voltage to the AD conversion unit. The detection power supply unit supplies a detection voltage for generating an abnormality detection analog signal separately from the conversion power supply unit.

  According to this abnormality detection apparatus, since the conversion power supply unit supplies the reference voltage to the AD conversion unit, the abnormality detection analog signal is generated from the detection voltage supplied by the detection power supply unit. Even if there is an abnormality in the reference voltage supplied to the unit, the abnormality detection analog signal is not affected. Therefore, the abnormality detection device can detect an abnormality of the AD conversion unit including the abnormality of the reference voltage.

  Preferably, the abnormality detection device further includes a conversion power supply unit, a detection power supply unit, and a temperature sensor. The conversion power supply unit supplies a reference voltage to the AD conversion unit. The detection power supply unit supplies a detection voltage for generating an abnormality detection analog signal separately from the conversion power supply unit. The temperature sensor measures the temperature of the abnormality detection device. The comparison unit detects an abnormality of the AD conversion unit by comparing the value after correcting the value of the abnormality detection digital signal based on the measurement value of the temperature sensor and the expected value stored in the nonvolatile memory. .

  According to this abnormality detection apparatus, since the conversion power supply unit supplies the reference voltage to the AD conversion unit, the abnormality detection analog signal is generated from the detection voltage supplied by the detection power supply unit. Even if there is an abnormality in the reference voltage supplied to the unit, the abnormality detection analog signal is not affected. Furthermore, even if the abnormality detection analog signal has a temperature characteristic, the value of the abnormality detection digital signal is corrected based on the temperature of the abnormality detection device measured by the temperature sensor. Unaffected by temperature characteristics of analog signals. Therefore, it is possible to accurately detect an abnormality in the AD conversion unit including an abnormality in the reference voltage.

  Preferably, in the abnormality detection device, the predetermined timing is at the time of shipping inspection of the abnormality detection device.

  According to this abnormality detection device, the value of the abnormality detection digital signal obtained by converting the abnormality detection analog signal by the AD conversion unit at the time of shipment inspection of the abnormality detection device is stored in the nonvolatile memory as an expected value. Therefore, the comparison unit can compare the result of AD conversion performed by the AD conversion unit performed at the time of shipping inspection with the result of AD conversion performed by the same AD conversion unit performed after shipment. That is, the comparison unit can detect an abnormality in the AD conversion unit by comparison with the normal AD conversion unit in the initial stage of manufacture.

  Preferably, in the abnormality detection device, the predetermined timing is a time of shipping inspection of an electronic device including the abnormality detection device.

  According to this abnormality detection device, the value of the abnormality detection digital signal obtained by converting the abnormality detection analog signal by the AD conversion unit at the time of shipment inspection of the electronic device including the abnormality detection device is stored in the nonvolatile memory as an expected value. . Therefore, the comparison unit can compare the result of AD conversion performed by the AD conversion unit performed at the time of shipping inspection with the result of AD conversion performed by the same AD conversion unit performed after shipment. That is, the comparison unit can detect an abnormality in the AD conversion unit by comparison with the normal AD conversion unit in the initial stage of manufacture.

Preferably, in the abnormality detection apparatus, the AD conversion unit is a ΔΣ AD conversion unit.
According to this abnormality detection apparatus, the comparison unit can accurately detect an abnormality in the ΔΣ type AD conversion unit.

  An abnormality detection device according to another aspect of the present invention includes a nonvolatile memory, a first input unit, a second input unit, an AD conversion unit, and a comparison unit. The nonvolatile memory stores an expected value for abnormality detection. A plurality of analog signals including predetermined abnormality detection analog signals are input to the first input unit. An analog signal obtained by inverting the polarity of the analog signal input to the first input unit is input to the second input unit. The AD conversion unit generates a digital signal based on the analog signal input to each of the first input unit and the second input unit. The comparison unit compares the value of the abnormality detection digital signal generated by the AD conversion unit based on the abnormality detection analog signal input to each of the first input unit and the second input unit with the expected value, An abnormality in the AD conversion unit is detected. In the nonvolatile memory, the value of the abnormality detection digital signal generated by the AD converter based on the abnormality detection analog signal input to each of the first input unit and the second input unit at a predetermined timing is an expected value. Is remembered as

  According to this abnormality detection device, the value of the abnormality detection digital signal obtained by converting the abnormality detection analog signal by the AD conversion unit at a predetermined timing is stored as an expected value in the nonvolatile memory, and the comparison unit calculates the expected value. It is possible to detect an abnormality in the AD conversion unit. Therefore, the abnormality detection apparatus can detect the abnormality of the AD conversion unit using the expected value in consideration of the individual difference of the AD conversion unit to be determined, and thus the abnormality of the AD conversion unit can be accurately determined regardless of the individual difference. It can be detected well. Further, an abnormality detection digital signal is generated by the AD conversion unit based on the abnormality detection analog signal input to each of the first input unit and the second input unit. As described above, the differential method is used for the signal input to the AD conversion unit, so that the influence of noise superimposed on the ground as in the single-ended method in which the abnormality detection analog signal is input with reference to the ground potential is used. The abnormality detection device can detect an abnormality of the AD conversion unit with higher accuracy.

  According to the present invention, the abnormality detection device can accurately detect an abnormality in the AD conversion unit regardless of individual differences.

It is a block diagram which shows roughly an example of a structure of the abnormality detection apparatus in 1st Embodiment. It is a block diagram which shows roughly an example of a structure of the abnormality detection apparatus in 2nd Embodiment. It is a block diagram which shows roughly an example of a structure of the abnormality detection apparatus in 3rd Embodiment. It is a block diagram which shows roughly an example of a structure of the abnormality detection apparatus in 4th Embodiment. It is a block diagram which shows roughly an example of a structure of the abnormality detection apparatus in a modification. It is a block diagram which shows roughly an example of a structure of the abnormality detection apparatus in a modification.

  Embodiments of the present invention will be described in detail with reference to the drawings. In the drawings to be referred to, the same or corresponding parts are denoted by the same reference numerals, and the description thereof will not be repeated.

[Abnormality detection apparatus in the first embodiment]
FIG. 1 is a block diagram schematically illustrating an example of the configuration of the abnormality detection device 10 according to the first embodiment. The abnormality detection device 10 is an electronic component in which a plurality of elements are combined into one package and enclosed in a package, and is mounted on the electronic device 100. The abnormality detection device 10 converts an analog signal from a sensor (not shown) into a digital signal and outputs the converted digital signal to the outside. The abnormality detection device 10 is not limited to an analog signal input from a sensor, and any analog signal input from the outside can be converted into a digital signal and output.

  As shown in FIG. 1, the abnormality detection apparatus 10 includes an input unit 2, an AD conversion unit 3, a conversion power supply unit 4, a comparison unit 5, a nonvolatile memory 6, and a memory 7.

  The abnormality detection device 10 corresponds to an embodiment of an “abnormality detection device”. The input unit 2 corresponds to an embodiment of an “input unit”. The AD conversion unit 3 corresponds to an embodiment of an “AD conversion unit”. The conversion power supply unit 4 corresponds to an embodiment of a “conversion power supply unit”. The comparison unit 5 corresponds to an embodiment of a “comparison unit”. The nonvolatile memory 6 corresponds to an embodiment of “nonvolatile memory”.

  The input unit 2 is a multiplexer to which an analog signal is input from a sensor or the like. The abnormality detection apparatus 10 is connected to each of a plurality of sensors, and a plurality of analog signals from each sensor are input to the input unit 2. For example, the analog signal A is input from the sensor a (not shown) to the input unit 2, while the analog signal B is input from the sensor b (not shown). Further, a known analog signal C is input to the input unit 2 as an abnormality detection analog signal for detecting an abnormality of the AD conversion unit 3. The input unit 2 selects one analog signal from the plurality of input analog signals and outputs the selected analog signal to the AD conversion unit 3.

  The signal input to the AD conversion unit 3 uses a single-ended system in which each analog signal is input with reference to the ground potential. The AD conversion unit 3 AD converts the analog signal from the input unit 2 into a digital signal based on the reference voltage Vref1 supplied from the conversion power supply unit 4. For example, in the case where 5V is used as the reference voltage Vref1, the AD conversion unit 3 has a case where the 8-bit digital signal after AD conversion becomes FF in hexadecimal conversion when the voltage of the input analog signal is 5V. When the voltage of the input analog signal is 2.5 V, the 8-bit digital signal after AD conversion becomes the median of 80 or 7F in hexadecimal conversion. Note that the AD conversion unit 3 is not limited to the one that converts an analog signal into an 8-bit digital signal, and may be one that converts, for example, a 16-bit digital signal.

  Here, there is a possibility that the characteristics of the AD conversion unit 3 may change with the passage of time after shipment. Therefore, the comparison unit 5 compares the conversion value C1 which is the value of the abnormality detection digital signal obtained by converting the abnormality detection analog signal C by the AD conversion unit 3 with the expected value C0 stored in the nonvolatile memory 6. Thus, it is determined whether or not the AD conversion unit 3 is abnormal. The expected value C0 is a fixed value stored in the nonvolatile memory 6 at the time of shipping inspection of the abnormality detecting device 10 or at the time of shipping inspection of the electronic device 100 including the abnormality detecting device 10, for example.

  Specifically, the input unit 2 periodically selects an analog signal C from the plurality of analog signals and outputs the analog signal C to the AD conversion unit 3. For example, the input unit 2 selects the analog signal C once and outputs it to the AD conversion unit 3 every time an analog signal other than the analog signal C is selected ten times. The AD conversion unit 3 converts the input analog signal C into a digital signal, and outputs the value of the digital signal to the comparison unit 5 as a conversion value C1. The comparison unit 5 compares the conversion value C1 with the expected value C0 stored in the non-volatile memory 6, and determines that the AD conversion unit 3 is normal when both match within a predetermined range, Are not within the predetermined range, it is determined that the AD conversion unit 3 is abnormal.

  When the comparison unit 5 determines that the AD conversion unit 3 is abnormal, the comparison unit 5 sets the error flag stored in the memory 7 to ON. The memory 7 can be accessed from the outside by a control device (not shown) provided in the electronic device 100, for example. When the error flag stored in the memory 7 is set to ON, the error flag is read by the control device of the electronic device 100 and predetermined error processing is performed. Alternatively, when the error flag stored in the memory 7 is set to ON, an error signal that can specify the occurrence of an abnormality is output to the control device of the electronic device 100. When the AD conversion unit 3 is not abnormal, the error flag remains set to OFF because the error flag is not set to ON by the comparison unit 5.

  As described above, the abnormality detection device 10 compares the conversion value C1 after AD conversion of the abnormality detection analog signal C with the expected value C0 stored in the nonvolatile memory 6, thereby Abnormalities can be detected.

  By the way, it is difficult to manufacture the AD conversion unit 3 having exactly the same characteristics due to various factors such as a used member, a manufacturing place, a manufacturing time, and a manufacturing method. However, if the same value is uniformly used for any AD conversion unit 3 without considering any individual difference of the AD conversion unit 3 with respect to the expected value C0 stored in the nonvolatile memory 6, AD conversion with high accuracy The case where the abnormality of the part 3 cannot be detected may occur.

  That is, when the same expected value C0 is uniformly used without considering the individual differences of the AD conversion unit 3, the conversion value C1 and the expected value C0 are within a predetermined range depending on the characteristics of the AD conversion unit 3 from the beginning of shipment. There may be cases where they do not match. Further, at the beginning of shipment of the AD conversion unit 3, even if the conversion value C1 and the expected value C0 barely coincide with each other within a predetermined range, the conversion value is obtained only by a slight characteristic deviation after the shipment of the AD conversion unit 3. There may be a case where C1 and the expected value C0 do not match within a predetermined range.

  Therefore, in the first embodiment, the nonvolatile memory 6 stores the value of the abnormality detection digital signal obtained by AD converting the abnormality detection analog signal C by the AD conversion unit 3 at a predetermined timing as the expected value C0. Yes.

  Specifically, the AD conversion unit 3 converts the abnormality detection analog signal C into a digital signal at the time of shipment inspection of the abnormality detection device 10 or at the time of shipment inspection of the electronic device 100 including the abnormality detection device 10. A conversion value C1 is obtained. The non-volatile memory 6 stores the conversion value C1 at the time of shipping inspection as an expected value C0. That is, in the abnormality detection device 10 according to the first embodiment, the expected value C0 corresponding to the AD conversion unit 3 is stored in the nonvolatile memory 6 for each individual.

  As described above, according to the abnormality detection device 10 in the first embodiment, the value of the abnormality detection digital signal when the abnormality detection analog signal C is converted by the AD conversion unit 3 at a predetermined timing is nonvolatile as the expected value C0. The comparison unit 5 can detect an abnormality in the AD conversion unit 3 using the expected value C0. Therefore, the abnormality detection apparatus 10 can detect the abnormality of the AD conversion unit 3 using the expected value C0 in consideration of the individual difference of the AD conversion unit 3 to be determined. 3 abnormalities can be detected with high accuracy.

  Further, according to the abnormality detection device 10 in the first embodiment, the value of the abnormality detection digital signal obtained by converting the abnormality detection analog signal C by the AD conversion unit 3 at the time of the shipment inspection of the abnormality detection device 10 is the expected value C0. It is stored in the nonvolatile memory 6. Therefore, the comparison unit 5 can compare the result of AD conversion performed by the AD conversion unit 3 performed at the time of shipping inspection with the result of AD conversion performed by the same AD conversion unit 3 performed after shipment. That is, the comparison unit 5 can detect an abnormality in the AD conversion unit 3 by comparison with the normal AD conversion unit 3 at the initial stage of manufacture.

[Abnormality detection apparatus in the second embodiment]
FIG. 2 is a block diagram schematically showing an example of the configuration of the abnormality detection device 20 in the second embodiment.

  Since the abnormality detection analog signal C generally has temperature characteristics, the analog signal C having the same value is not always input to the input unit 2. If the value of the analog signal C varies due to temperature characteristics, there may be a case where the abnormality detection of the AD conversion unit 3 by the comparison unit 5 cannot be performed with high accuracy.

  Therefore, the abnormality detection device 20 in the second embodiment is configured such that the abnormality detection analog signal C is generated from the reference voltage Vref1 supplied by the conversion power supply unit 4. In other respects, the abnormality detection device 20 has basically the same configuration as the abnormality detection device 10 in the first embodiment.

  Specifically, as shown in FIG. 2, the abnormality detection device 20 includes a resistor 21 and a resistor 22. The resistor 21 has one end connected to the conversion power supply unit 4 and the other end connected to the resistor 22. The resistor 22 has one end connected to the resistor 21 and the other end connected to the ground. A signal line of the analog signal C input to the input unit 2 is connected to the signal lines of the resistors 21 and 22. The reference voltage Vref1 supplied from the conversion power supply unit 4 causes a voltage drop in the resistor 21, and the voltage Vref2 after the voltage drop is input to the input unit 2 as an abnormality detection analog signal C.

  As described above, according to the abnormality detection device 20 in the second embodiment, the conversion power supply unit 4 supplies the reference voltage Vref1 to the AD conversion unit 3, and the abnormality detection analog signal C is generated from the reference voltage Vref1. The For this reason, when the reference voltage Vref1 decreases due to the temperature characteristics, the value of the abnormality detection analog signal C also decreases according to the decrease degree of the reference voltage Vref1, and conversely, when the reference voltage Vref1 increases due to the temperature characteristics, the reference voltage Vref1 increases. The value of the abnormality detection analog signal C also increases in accordance with the degree of increase in Vref1. Thus, the abnormality detection analog signal C has the same temperature characteristics as the reference voltage Vref1.

  For example, as described above, when 5V is used as the reference voltage Vref1, when the value of the analog signal C is 2.5V, the 8-bit digital signal after AD conversion becomes the median of 80 or 7F in hexadecimal conversion. Become. From this state, when the value of the analog signal C decreases from 2.5V to 2.0V due to temperature characteristics, the reference voltage Vref1 also decreases from 5V to 4V. Therefore, the 8-bit digital signal after AD conversion is It becomes the median of 80 or 7F in hexadecimal, and is not affected by temperature characteristics.

  As described above, according to the abnormality detection device 20 in the second embodiment, the temperature characteristic of the abnormality detection analog signal C does not affect the abnormality detection of the AD conversion unit 3. Abnormalities can be detected with high accuracy.

  The resistor 21 and the resistor 22 may be provided outside the abnormality detection device 20.

[Abnormality Detection Device in Third Embodiment]
FIG. 3 is a block diagram schematically showing an example of the configuration of the abnormality detection device 30 in the third embodiment.

  Since the conversion power supply unit 4 may deteriorate, the reference voltage Vref 1 having the same value is not always supplied from the conversion power supply unit 4 to the AD conversion unit 3. If the value of the reference voltage Vref1 varies, there may occur a case where the abnormality detection of the AD conversion unit 3 by the comparison unit 5 cannot be performed with high accuracy.

  Therefore, the abnormality detection device 30 according to the third embodiment is configured such that the abnormality detection analog signal C is supplied by a detection power supply unit 31 different from the conversion power supply unit 4. In other respects, the abnormality detection device 30 has basically the same configuration as the abnormality detection device 10 in the first embodiment. The detection power supply unit 31 corresponds to an embodiment of a “detection power supply unit”.

  Specifically, as shown in FIG. 3, the abnormality detection device 20 includes a detection power supply unit 31. The detection power supply unit 31 supplies the detection voltage Vref2 as a voltage for generating the abnormality detection analog signal C. An abnormality detection analog signal C generated from the detection voltage Vref <b> 2 is input to the input unit 2.

  Thus, according to the abnormality detection device 30 in the third embodiment, the conversion power supply unit 4 supplies the reference voltage Vref1 to the AD conversion unit 3, while the detection voltage Vref2 supplied by the detection power supply unit 31. From this, an abnormality detection analog signal C is generated. For this reason, even if the reference voltage Vref1 supplied to the AD conversion unit 3 is abnormal, the abnormality detection analog signal C is not affected. Therefore, the abnormality detection device 30 can detect an abnormality in the AD conversion unit 3 including an abnormality in the reference voltage Vref1.

The power supply unit 31 for detection may be provided outside the abnormality detection device 30.
[Abnormality detection apparatus in the fourth embodiment]
FIG. 4 is a block diagram schematically showing an example of the configuration of the abnormality detection device 40 in the fourth embodiment.

  As described above, when the abnormality detection analog signal C is generated from the reference voltage Vref1 supplied by the conversion power supply unit 4 as in the abnormality detection device 20 in the second embodiment, the abnormality detection The temperature characteristics of the analog signal C do not affect the abnormality detection of the AD converter 3. However, when configured like the abnormality detection device 20 in the second embodiment, it is not possible to detect an abnormality in the reference voltage Vref1 due to deterioration of the conversion power supply unit 4.

  On the other hand, as described above, when the abnormality detection analog signal C is configured to be supplied by the detection power supply unit 31 different from the conversion power supply unit 4 as in the abnormality detection device 30 in the third embodiment. The abnormality of the reference voltage Vref1 due to the deterioration of the conversion power supply unit 4 can be detected. However, when configured like the abnormality detection device 30 in the third embodiment, the temperature characteristics of the abnormality detection analog signal C may affect the abnormality detection of the AD conversion unit 3.

  Therefore, in the abnormality detection device 40 according to the fourth embodiment, after the abnormality detection analog signal C is supplied by the detection power supply unit 31 different from the conversion power supply unit 4 and AD-converted by the AD conversion unit 3. The conversion value C1 is corrected based on the temperature of the abnormality detection device 40 measured by the temperature sensor 42. Then, the comparison unit 5 compares the conversion value C2 after the conversion value C1 is temperature-corrected with the expected value C0 stored in the nonvolatile memory 6 to determine whether or not the AD conversion unit 3 is abnormal. Determine whether. In other respects, the abnormality detection device 30 has basically the same configuration as the abnormality detection device 10 in the first embodiment. The temperature sensor 42 corresponds to an embodiment of a “temperature sensor”.

  Specifically, as shown in FIG. 4, the abnormality detection device 40 includes a detection power supply unit 31 and a temperature sensor 42. The detection power supply unit 31 supplies the detection voltage Vref2 as a voltage for generating the abnormality detection analog signal C. An abnormality detection analog signal C generated from the detection voltage Vref <b> 2 is input to the input unit 2. The temperature sensor 42 measures the internal temperature of the abnormality detection device 40. The measured value D of the temperature sensor 42 is input to the input unit 2.

  The measurement value D input to the input unit 2 is AD converted into a digital signal by the AD conversion unit 3 and becomes a converted value D1. The comparison unit 5 corrects the conversion value C1 with the conversion value D1 to obtain a conversion value C2 after temperature correction. For example, the conversion value C2 is calculated by the following arithmetic expression.

Conversion value C2 = conversion value C1 × (σ / conversion value D1)
Note that σ is an arbitrary number, and for example, σ = 5 is used.

  The comparison unit 5 compares the converted value C2 after temperature correction and the expected value C0 stored in the nonvolatile memory 6 and determines that the AD conversion unit 3 is normal when the two values match. When the two do not match, it is determined that the AD conversion unit 3 is abnormal.

  Thus, according to the abnormality detection device 40 in the fourth embodiment, the conversion power supply unit 4 supplies the reference voltage Vref1 to the AD conversion unit 3, while the detection voltage Vref2 supplied by the detection power supply unit 31. Therefore, even if the reference voltage Vref1 supplied to the AD converter 3 is abnormal, the abnormality detection analog signal C is not affected. Furthermore, even if the abnormality detection analog signal C has temperature characteristics, the conversion value C1 after the analog signal C is AD converted by the AD conversion unit 3 is the temperature of the abnormality detection device 40 measured by the temperature sensor 42. Therefore, the abnormality detection device 40 is not affected by the temperature characteristics of the abnormality detection analog signal C. Therefore, it is possible to accurately detect an abnormality in the AD conversion unit 3 including an abnormality in the reference voltage Vref1.

  The power supply unit 31 for detection and the temperature sensor 42 may be provided outside the abnormality detection device 40.

[Modification]
In the above-described embodiment, the single-end method in which each analog signal is input with respect to the ground potential is used for signal input to the AD conversion unit 3. However, the signal input to the AD conversion unit 3 is not limited to the single end method, and other methods may be used.

  For example, as illustrated in FIG. 5, the abnormality detection device 50 includes an input unit 52 that is different from the input unit 2. The input unit 2 illustrated in FIG. 5 corresponds to an embodiment of a “first input unit”, and the input unit 52 corresponds to an embodiment of a “second input unit”. Similar to the input unit 2, the input unit 52 is a multiplexer to which a plurality of analog signals from each sensor are input. An analog signal obtained by inverting the polarity of the analog signal input to the input unit 2 is input to the input unit 52. For example, the analog signal A ′ whose polarity is inverted from the analog signal A input to the input unit 2 is input to the input unit 52, and the analog signal B ′ whose polarity is inverted from the analog signal B input to the input unit 2 is input to the input unit 52. Is done. Further, the analog signal C ′ obtained by inverting the polarity of the abnormality detection analog signal C input to the input unit 2 is input to the input unit 52. The input unit 52 selects one analog signal from the plurality of input analog signals and outputs the selected analog signal to the AD conversion unit 3.

  An analog signal whose polarity is not inverted is input from the input unit 2 to the AD conversion unit 3, and an analog signal whose polarity is inverted is input from the input unit 52. Thus, in the abnormality detection device 50 according to the modification, a differential method is used as a signal input to the AD conversion unit 3. Then, the AD conversion unit 3 converts the abnormality detection analog signal C input to the input unit 2 and the abnormality detection analog signal C ′ having the polarity inverted input to the input unit 52 into the abnormality detection digital signal. Generate.

  Thus, according to the abnormality detection device 50 in the modification, based on the abnormality detection analog signal C input to the input unit 2 and the polarity detection abnormality detection analog signal C ′ input to the input unit 52. The AD converter 3 generates an abnormality detection digital signal. In this way, by using a differential method for signal input to the AD conversion unit 3, noise that is superimposed on the ground as in the single-ended method in which an abnormality detection analog signal is input with reference to the ground potential is used. The abnormality detection device 50 is less affected and can detect an abnormality of the AD conversion unit 3 with higher accuracy.

  The configuration in which the signal input to the AD conversion unit 3 is performed in a differential manner as in the abnormality detection device 50 illustrated in FIG. 5 is applied to any of the abnormality detection devices illustrated in FIGS. be able to.

  Further, the AD conversion unit 3 may perform AD conversion using any method such as flash type or successive approximation type. For example, ΔΣ type AD conversion as provided in the abnormality detection device 60 shown in FIG. The part 63 may be used. Note that the ΔΣ AD converter 63 illustrated in FIG. 6 corresponds to an embodiment of a “ΔΣ AD converter”.

  The ΔΣ AD converter 63 integrates, for example, a difference between an analog signal input at each sampling frequency and a digital signal output digitally one cycle before, and compares the integration result with a reference value to obtain a digital signal. Is output. The ΔΣ AD converter 63 may be any device that generates a digital signal by a method used in a generally known ΔΣ AD converter in addition to the method described above.

  Then, the comparison unit 5 compares the conversion value C1 that is the value of the digital signal output from the ΔΣ AD conversion unit 63 with the expected value C0 stored in the nonvolatile memory 6, and when both match, While it is determined that the ΔΣ AD converter 63 is normal, it is determined that the ΔΣ AD converter 63 is abnormal when the two do not match.

  As described above, according to the abnormality detection device 60 in the modification, the comparison unit 5 can also detect the abnormality of the ΔΣ AD conversion unit 63 with high accuracy.

  Note that the configuration including the ΔΣ AD converter 63 as in the abnormality detection device 60 illustrated in FIG. 6 can be applied to any of the abnormality detection devices illustrated in FIGS. 1 to 4 described above. Further, a configuration in which signal input to the AD conversion unit 3 is performed in a differential manner as in the abnormality detection device 50 illustrated in FIG. 5, and a ΔΣ AD conversion unit 63 as in the abnormality detection device 60 illustrated in FIG. You may apply both to a structure to the abnormality detection apparatus shown in FIGS. 1-4 mentioned above.

  In the above-described embodiment, the time of shipping inspection of the abnormality detection device 10 is exemplified as the predetermined timing at which the expected value C0 is stored in the nonvolatile memory 6, but the predetermined timing is not limited to the time of shipping inspection. For example, the predetermined timing may be when the abnormality detection device 10 is incorporated into a product after the shipment of the abnormality detection device 10, or power is supplied to the abnormality detection device 10 in a state where the abnormality detection device 10 is incorporated into the product. May be provided, and any timing may be used as long as the AD conversion unit 3 is in a normal state.

  In the abnormality detection device 40 shown in FIG. 4 described above, the temperature sensor 42 measures the internal temperature of the abnormality detection device 40, but the measurement range of the temperature sensor 42 is not limited to this. For example, the temperature sensor 42 may measure the temperature of the input unit 2 or the temperature of the power supply unit 31 for detection, and if the temperature characteristic of the abnormality detection analog signal C is known, Any range may be measured.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

  2,52 input unit, 3 AD conversion unit, 4 conversion power source unit, 5 comparison unit, 6 nonvolatile memory, 7 memory, 10, 20, 30, 40, 50, 60 abnormality detection device, 21, 22 resistor, 31 power supply unit for detection, 42 temperature sensor, 63 ΔΣ type AD conversion unit.

Claims (8)

A non-volatile memory in which an expected value for anomaly detection is stored;
An input unit to which a plurality of analog signals including a predetermined abnormality detection analog signal are input;
An AD conversion unit that converts an analog signal input to the input unit into a digital signal;
Comparing a value of the abnormality detection digital signal obtained by converting the abnormality detection analog signal by the AD conversion unit with the expected value, thereby detecting an abnormality of the AD conversion unit,
The abnormality detection device, wherein the nonvolatile memory stores, as the expected value, the value of the abnormality detection digital signal when the analog signal for abnormality detection is converted by the AD converter at a predetermined timing. A conversion power supply for supplying a reference voltage to the AD converter;
The abnormality detection device according to claim 1, wherein the abnormality detection analog signal is generated from the reference voltage supplied by the conversion power supply unit. A conversion power supply for supplying a reference voltage to the AD converter;
The abnormality detection device according to claim 1, further comprising: a detection power supply unit that supplies a detection voltage for generating the abnormality detection analog signal separately from the conversion power supply unit. A conversion power supply for supplying a reference voltage to the AD converter;
A detection power supply for supplying a detection voltage for generating the abnormality detection analog signal separately from the conversion power supply,
A temperature sensor that measures the temperature of the abnormality detection device;
The comparison unit compares the value after correcting the value of the abnormality detection digital signal based on the measurement value of the temperature sensor with the expected value stored in the nonvolatile memory, thereby performing the AD conversion. The abnormality detection device according to claim 1, wherein an abnormality of a part is detected.   The abnormality detection device according to claim 1, wherein the predetermined timing is a shipping inspection of the abnormality detection device.   The abnormality detection device according to claim 1, wherein the predetermined timing is a shipping inspection time of an electronic device including the abnormality detection device.   The abnormality detection apparatus according to claim 1, wherein the AD conversion unit is a ΔΣ AD conversion unit. A non-volatile memory in which an expected value for anomaly detection is stored;
A first input unit to which a plurality of analog signals including a predetermined abnormality detection analog signal are input;
A second input unit to which an analog signal obtained by inverting the polarity of the analog signal input to the first input unit is input;
An AD conversion unit that generates a digital signal based on an analog signal input to each of the first input unit and the second input unit;
By comparing the value of the abnormality detection digital signal generated by the AD converter based on the abnormality detection analog signal input to each of the first input unit and the second input unit with the expected value. A comparison unit for detecting an abnormality of the AD conversion unit,
In the nonvolatile memory, the abnormality detection digital when generated by the AD converter based on the abnormality detection analog signal input to each of the first input unit and the second input unit at a predetermined timing An abnormality detection apparatus in which a signal value is stored as the expected value.

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