Patent Description:
In Patent Document <NUM> cited below, a technique related to a method of inspecting a memory in a memory inspection mode is disclosed, that relates to an analog-to-digital conversion circuit having multiple circuit parts each of which is configured to include a comparator and a memory. Examples of integrated circuit devices with monitoring or diagnostic functions are disclosed in <CIT>, <CIT>, <CIT> and <CIT>.

Meanwhile, conventionally, as a diagnostic method of an integrated circuit that executes processing on a sensor signal output from a sensor, a diagnostic method that executes diagnosis of the integrated circuit based on the value of an output signal (i.e., a sensor signal or a test signal after processed by the integrated circuit) output from the integrated circuit, in a state of the sensor being connected to the input terminal, or in a state of a generation source of the test signal being connected to the input terminal, has been used. In such an integrated circuit, abnormalities are likely to occur in an amplifier and an A-D converter, and it is favorable to detect such abnormalities by diagnosing the integrated circuit.

However, in the conventional diagnostic method, the value of the output signal output from the integrated circuit is affected by an influence of the outside of the integrated circuit (e.g., the sensor, a connection line to the sensor, the generation source of the test signal, a connection line to the generation source of the test signal, etc.) and an influence of the inside of the integrated circuit; therefore, it is not possible to easily and securely determine whether or not the integrated circuit is functioning normally, only by the value of the output signal output from the integrated circuit.

According to the invention, there is provided an integrated circuit as defined in appended claim <NUM>. Other advantageous embodiments are defined in the corresponding dependent claims.

There is also disclosed an integrated circuit that executes processing on a sensor signal input from a sensor via an input terminal. The integrated circuit includes a processing path through which a series of processing is executed on the sensor signal; and a test signal generation source configured to generate a test signal for self-diagnosis, to feed the test signal into the processing path.

By the integrated circuit according to the one embodiment, whether or not the integrated circuit is functioning normally can be determined easily and securely.

In the following, with reference to the drawings, the one embodiment will be described.

<FIG> is a diagram illustrating a configuration of a diagnostic system <NUM> according to the one embodiment. A diagnostic system <NUM> illustrated in <FIG> is provided with an IC (Integrated Circuit) <NUM> and an MCU (Micro Controller Unit) <NUM>. The IC <NUM> is an integrated circuit that executes predetermined processing on a sensor signal output from a sensor. For example, the IC <NUM> can convert the sensor signal output from the sensor from an analog signal to a digital signal. The IC <NUM> has a "diagnostic mode". In the "diagnostic mode," the IC <NUM> generates a test signal by a test signal generation source <NUM> provided inside, and, by feeding the test signal into a processing path 20A of the sensor signal, can execute a series of processing on the test signal (same processing as executed on the sensor signal). The MCU <NUM> is an example of a "determination means" that obtains from the IC <NUM> the test signal after the series of processing has been executed, and based on the obtained test signal, can execute determination on fault diagnosis of the IC <NUM>.

As illustrated in <FIG>, the IC <NUM> includes a first multiplexer <NUM>, a second multiplexer <NUM>, a PGA (Programmable Gain Amplifier) <NUM>, an A-D converter <NUM>, a digital processing circuit <NUM>, a test signal generation source <NUM>, an internal sensor <NUM> (e.g., a temperature sensor), and a power supply <NUM>.

Note that in the example illustrated in <FIG>, the IC <NUM> is provided with three pairs of input terminals A0P, A0M, A1P, A1M, A2P, and A2M, where each pair includes two input terminals (a +terminal and a -terminal). Accordingly, the IC <NUM> can be connected with three sensors, and for each pair of input terminals, two output signal lines connected to a differential sensor, or one output signal line connected to a single-ended sensor can be connected.

The first multiplexer <NUM> (denoted as MUX0 in the figure) is connected to each of the multiple input terminals and the internal sensor <NUM>. The first multiplexer <NUM> selects one of sensor signals from among multiple sensor signals input from the multiple input terminals and the internal sensor <NUM>, to output the selected one of the sensor signals to the A-D converter <NUM>. Also, the first multiplexer <NUM> is an example of a "switching means" that is connected to the test signal generation source <NUM>, and can select a test signal output from the test signal generation source <NUM>, to output the test signal to the A-D converter <NUM>.

The second multiplexer <NUM> (denoted as MUX1 in the figure) is connected to each of the multiple input terminals and the internal sensor <NUM>. The second multiplexer <NUM> selects one of the sensor signals from among the multiple sensor signals input from the multiple input terminals and the internal sensor <NUM>, to output the selected one of the sensor signals to the PGA <NUM>. Also, the second multiplexer <NUM> is an example of a "switching means" that is connected to the test signal generation source <NUM>, and can select the test signal output from the test signal generation source <NUM>, to output the test signal to the PGA <NUM>.

The PGA <NUM> is connected between the output terminals of the second multiplexer <NUM> and the input terminals of the first multiplexer <NUM>. The PGA <NUM> is an amplifier whose gain can be changed. The PGA <NUM> amplifies one of the sensor signals output from the second multiplexer <NUM>, to output the amplified signal to the input terminals of the first multiplexer <NUM>. In this case, the first multiplexer <NUM> can select the one of the sensor signals output from the PGA <NUM>, to output the one of the sensor signals to the A-D converter <NUM>. In other words, the first multiplexer <NUM> can output the one of the sensor signals amplified by the PGA <NUM> to the A-D converter <NUM>.

The A-D converter <NUM> (denoted as "ADC" in the figure) is connected to the output terminals of the first multiplexer <NUM>. The A-D converter <NUM> converts one of the sensor signals (one sensor signal not amplified by the PGA <NUM> or one sensor signal amplified by the PGA <NUM>) output from the first multiplexer <NUM>, from an analog signal to a digital signal, to output the converted signal to the digital processing circuit <NUM>.

The digital processing circuit <NUM> is connected to the output terminal of the A-D converter <NUM>. The digital processing circuit <NUM> includes a register 25A. The register 25A stores one sensor signal output from the A-D converter <NUM>. Also, the digital processing circuit <NUM> applies predetermined digital signal processing (e.g., digital filtering, data transmission to the MCU <NUM> via I2C communication, etc.) to one sensor signal (digital signal) output from the A-D converter <NUM> or one sensor signal (digital signal) stored in the register 25A. For example, the digital processing circuit <NUM> outputs one sensor signal stored in the register 25A to the MCU <NUM> via the output terminal of the IC <NUM>.

In the "diagnostic mode", the test signal generation source <NUM> generates a test signal for self-diagnosis to self-diagnose the state of the processing path 20A of the sensor signal, and feeds the test signal into the processing path 20A of the sensor signal. The output terminals of the test signal generation source <NUM> are connected to both of the input terminals of the first multiplexer <NUM> and the input terminals of the second multiplexer <NUM>. In the present embodiment, the processing path 20A of the sensor signal into which the test signal is fed includes, as processing blocks, the second multiplexer <NUM>, the PGA <NUM>, the first multiplexer <NUM>, and the A-D converter <NUM>.

The power supply <NUM> generates electric power required for the respective components of the IC <NUM> (the PGA <NUM>, the A-D converter <NUM>, and the digital processing circuit <NUM>), to supply the electric power to the respective components of the IC <NUM> (the PGA <NUM>, the A-D converter <NUM>, and the digital processing circuit <NUM>).

<FIG> is a diagram illustrating a processing path 20A in the IC <NUM> according to the one embodiment. In <FIG>, the processing path 20A in the IC <NUM> is indicated by an arrow.

As illustrated in <FIG>, in the "diagnostic mode" of the IC <NUM>, a test signal generated by the test signal generation source <NUM> is fed into the signal processing path 20A of the sensor signal. Then, the test signal fed into the processing path 20A is input into the PGA <NUM> via the second multiplexer <NUM>, and amplified by the PGA <NUM> with a predetermined gain.

The test signal amplified by the PGA <NUM> is input into the A-D converter <NUM> through the first multiplexer <NUM>, and converted from an analog signal to a digital signal by the A-D converter <NUM>. The test signal converted to the digital signal by the A-D converter <NUM> is stored in the register 25A of the digital processing circuit <NUM>.

Note that in the "diagnostic mode", the test signal generation source <NUM> feeds two test signals S1 and S2 sequentially into the path illustrated in <FIG>. In addition, the PGA <NUM> causes the gain of the test signal S1 fed first and the gain of the test signal S2 fed second to be different from each other. For example, in the present embodiment, the PGA <NUM> amplifies the test signal S1 with a gain of <NUM> times, and amplifies the test signal S2 with a gain of <NUM> times (i.e., twice the gain of the test signal S1). Accordingly, the test signal S1 amplified <NUM> times and the test signal S2 amplified <NUM> times are stored in the register 25A of the digital processing circuit <NUM>.

The two test signals S1 and S2 stored in the register 25A of the digital processing circuit <NUM> are read by the MCU <NUM>, to be used for determining a diagnostic result of the IC <NUM>.

<FIG> is a flow chart illustrating the order of operations in the diagnostic mode executed by the IC <NUM> according to the one embodiment.

First, the IC <NUM> is activated when the power is switched on by a user (Step S301).

Next, the IC <NUM> determines whether or not the mode has been switched to the "diagnostic mode" (Step S302). For example, the IC <NUM> determines that the mode has been switched to the "diagnostic mode" when the user has made settings to switch the register to the "diagnostic mode.

If it is determined at Step S302 that the mode has not been switched to the "diagnostic mode" (NO at Step S302), the IC <NUM> executes the determination process at Step S302 again.

On the other hand, if it is determined at Step S302 that the mode has been switched to the "diagnostic mode" (YES at Step S302), the IC <NUM> determines whether a predetermined processing execution command has been input from the user (Step S303).

If it is determined at Step S303 that a predetermined processing execution command has not been input (NO at Step S303), the IC <NUM> executes the determination process at Step S303 again.

On the other hand, if it is determined at Step S303 that a predetermined processing execution command has been input (YES at Step S303), the IC <NUM> switches the first multiplexer <NUM> and the second multiplexer <NUM> so as to have a test signal fed into the processing path 20A of the sensor signal (Step S304).

Then, the IC <NUM> causes the test signal generation source <NUM> to generate a first test signal S1, and to feed the test signal S1 into the sensor signal processing path 20A (Step S305).

Accordingly, once a series of processing (amplification processing and A-D conversion processing) is executed on the test signal S1, the digital processing circuit <NUM> stores the test signal S1 output from the A-D converter <NUM> (i.e., the test signal S1 after the series of processing has been executed) in the register 25A (Step S306).

Next, the IC <NUM> determines whether or not a process for the second test signal S2 has been completed (i.e., whether or not both test signals S1 and S2 were stored in the register 25A) (Step S307).

If it is determined at Step S307 that a process for the second test signal S2 has not been completed (NO at Step S307), the IC <NUM> changes the gain of the PGA <NUM> to twice the gain of the first time (Step S308), and then, executes steps from Steps S305 to S306 again to execute the series of processing on the second test signal S2, and stores the test signal S2 after the series of processing has been executed, in the register 25A.

Then, if it is determined at Step S307 that the process for the second test signal S2 has been completed (YES at Step S307), the IC <NUM> ends the series of processing illustrated in <FIG>.

Note that the predetermined processing execution command described above is common to that in the "normal operation mode". When the predetermined processing execution command is input in the "normal operation mode," the IC <NUM> feeds a sensor signal into the processing path 20A of the sensor signal, to execute a series of processing (amplification processing and A-D conversion processing) on the sensor signal.

<FIG> is a flow chart illustrating steps of a determination process executed by the MCU <NUM> according to the one embodiment.

First, the MCU <NUM> reads the two test signals S1 and S2 from the register 25A provided in the IC <NUM> (Step S401).

Next, the MCU <NUM> calculates a determination value based on the two test signals S1 and S2 according to a predetermined calculation formula (Step S402). Then, the MCU <NUM> determines the diagnostic result of the IC <NUM>, based on the determination value calculated at Step S402 (Step S403).

For example, the MCU <NUM> calculates the determination value according to the predetermined calculation formula {S2/S1}. Then, the MCU <NUM> determines that the diagnostic result of the IC <NUM> is "normal" if the calculated determination value is within a predetermined numerical range centered around "<NUM>" (e.g., <NUM> to <NUM>). On the other hand, the MCU <NUM> determines that the diagnostic result of the IC <NUM> is "abnormal" if the calculated determination value is outside the predetermined numerical range centered around "<NUM>". A determination result being "abnormal" indicates that there is an abnormality at some location related to the processing path 20A inside the IC <NUM> (the PGA <NUM>, the A-D converter <NUM>, the power supply <NUM>, etc.).

This is because, as already described, in the present embodiment, the gain used when amplifying the second test signal S2 by the PGA <NUM> is set to twice (i.e. <NUM> times) the gain (<NUM> times) used when amplifying the first test signal S1 by the PGA <NUM>, and hence, if there is no abnormality along the processing path 20A of the sensor signal to which the two test signals S1 and S2 are fed, the determination value calculated by the predetermined calculation formula (S2/S1) should be "<NUM>".

Then, the MCU <NUM> outputs the diagnosis result ("normal" or "abnormal") determined at Step S403 by a predetermined output method (Step S404), and ends the series of processing illustrated in <FIG>. As the predetermined output method, for example, a method of outputting to a higher-level application, to cause the higher-level application to notify the user by a predetermined notice method (e.g., display, audio output, etc.), may be considered. However, the method is not limited as such; the predetermined output method may be a method of storing the diagnostic result in a memory, a method of transmitting the diagnostic result to the outside, or the like.

As described above, the IC <NUM> according to the one embodiment is the IC <NUM> that executes processing on a sensor signal input from a sensor via the input terminal, and is provided with the processing path 20A that executes a series of processing on the sensor signal, and the test signal generation source <NUM> that generates a test signal for self-diagnosis, and feeds the test signal into the processing path 20A.

Accordingly, the IC <NUM> according to the one embodiment can execute self-diagnosis with a stable test signal that is not affected by the connection state of the sensor to the input terminal. In other words, in the IC <NUM> according to the one embodiment, it is obvious that the IC <NUM> is abnormal if the value of the test signal output from the IC <NUM> is abnormal, and the IC <NUM> is normal if the value of the test signal output from the IC <NUM> is normal. Therefore, by the IC <NUM> according to the one embodiment, whether or not the IC <NUM> is functioning normally can be determined easily and securely.

Also, the IC <NUM> according to the one embodiment further includes the first multiplexer <NUM> and the second multiplexer <NUM> that switch a signal to be fed into the processing path 20A from a sensor signal to a test signal.

Accordingly, in the IC <NUM> according to the one embodiment, feeding of a test signal from the test signal generation source <NUM> to the processing path 20A for a sensor signal can be implemented with a relatively simple configuration. Also, the IC <NUM> according to the one embodiment can easily make switching between the "normal operation mode" and the "diagnostic mode.

Also, in the IC <NUM> according to the one embodiment, the test signal generation source <NUM> feeds multiple test signals sequentially into the processing path 20A, and the PGA <NUM> provided in the processing path 20A amplifies the multiple test signals with respective gains different from one another.

Accordingly, the IC <NUM> according to the one embodiment can determine relatively easily and securely whether or not the multiple test signals output from the processing path 20A have been amplified normally, by comparing the values of the multiple test signals.

Also, the diagnostic system <NUM> according to the one embodiment includes the IC <NUM>, and the MCU <NUM> that has a function as a determination device to determine a result of self-diagnosis of the IC <NUM>, based on a test signal after a series of processing has been executed on the processing path 20A.

Accordingly, the diagnostic system <NUM> according to the one embodiment can determine easily and securely by the MCU <NUM>, whether or not the IC <NUM> is functioning normally.

As above, the one embodiment of the present invention have been described; note that the present invention is not limited to such an embodiment.

For example, in the one embodiment, although the function as the "determination device" is provided in the MCU <NUM> outside the IC <NUM>, it is not limited as such; the function as the "determination device" may be provided inside the IC <NUM> (digital processing circuit <NUM>) or on an external device other than the MCU <NUM>.

Also, for example, in the one embodiment, although examples have been described in which the present invention is applied to the IC <NUM> that executes amplification and A-D conversion of a sensor signal, it is not limited as such; the present invention can be applied to any integrated circuit that can execute some processing on a sensor signal.

For example, the IC <NUM> described in the above embodiment may be used, in a load detector that detects the load applied to an object, as a what-is-called AFE (Analog Front End) that connects a strain gauge to output an analog signal and a microcomputer to execute digital processing to amplify and A-D convert the analog signal. However, the connection is not limited as such; the IC <NUM> may be connected to a sensor other than a strain gauge, and may be used in a system configuration other than the detection system <NUM> described in the embodiment as above.

Claim 1:
An integrated circuit (<NUM>) that executes processing on a sensor signal input from a sensor via an input terminal, comprising:
a processing path (20A) through which a series of processing is executed on the sensor signal;
a test signal generation source (<NUM>) configured to generate a test signal for self-diagnosis, and to feed the test signal into the processing path;
a register (25A) configured to store the test signal; and
a determination means (<NUM>) configured to determine a result of the self-diagnosis, based on the test signal after the series of processing has been executed through the processing path,
wherein the processing path includes an amplifier (<NUM>) configured to amplify the test signal with a variable gain,
wherein the test signal generation source feeds a plurality of test signals sequentially into the processing path,
wherein the amplifier is configured to amplify a first test signal of the plurality of test signals with a first gain, and amplify a second test signal of the plurality of test signals with a second gain different from the first gain,
wherein the register is configured to store a first processed signal that is the first test signal amplified with the first gain, and a second processed signal that is the second test signal amplified with the second gain, and
wherein the determination means is configured to determine the result of the self-diagnosis, based on the first processed signal and the second processed signal.