JP5999550B2 - Adjustment circuit using nonvolatile memory and physical quantity sensor provided with the same - Google Patents

Description

  The present invention includes an output terminal that outputs an electrical signal proportional to a physical quantity, and a reference terminal that always outputs only an output zero-point potential proportional to the physical quantity, and the zero point and span of the electrical signal proportional to the physical quantity. Further, the present invention relates to a physical quantity sensor including a circuit that adjusts the temperature of the zero point and the span, and a nonvolatile memory that stores the adjustment amount and the correction amount.

Conventionally, for the purpose of improving the accuracy of physical quantity sensors, an adjustment circuit that adjusts the zero point and span of the electrical signal output proportional to the physical quantity, and a temperature correction circuit that corrects the temperature change of the zero point and the span are provided. An apparatus having a trimming operation mode for storing adjustment information such as the above-described zero point and span adjustment amounts and temperature correction circuit correction amounts in a nonvolatile memory has been introduced.
In this trimming operation mode, a signal sequence based on a ternary voltage generated at a higher voltage than that in the normal operation is applied to the output terminal, so that an electric signal proportional to a physical quantity is output and a nonvolatile memory is connected. The mode transition control to the trimming operation mode for writing the adjustment information is performed. (For example, see Patent Document 1)

Japanese Patent No. 4244886

  However, the sensor circuit described in Patent Document 1 is normally used for an output terminal as a transition control between a normal operation mode for outputting an electrical signal proportional to a physical quantity and a trimming operation mode for writing adjustment information to a nonvolatile memory. The circuit scale may increase because it is necessary to provide a circuit that applies a signal sequence composed of three-valued voltages generated at a voltage higher than the voltage and separates the applied signal sequence.

  In addition, since a signal string composed of ternary voltages generated at a higher voltage than the normal operation of outputting an electrical signal proportional to a physical quantity is applied to the output terminal, the output terminal has a higher voltage than the power supply voltage. Therefore, it is necessary to add a protection circuit to prevent damage to the circuit, and the circuit scale may increase.

  Further, the data pattern included in the signal string composed of ternary voltages generated at a higher voltage than the normal operation at the output terminal is a specific pattern indicating a transition signal to the trimming operation mode in which the adjustment information to the nonvolatile memory is written. It is difficult to reduce the cost of the circuit because a determination circuit for deception is necessary to determine a certain thing, and the circuit may be complicated and the circuit scale may increase.

  The present invention has been made in view of such circumstances, and at least a power supply terminal that applies power to the circuit, a GND terminal that is a reference potential of the circuit, an output terminal that outputs a physical quantity as an electrical signal, and It has a reference terminal that outputs the zero point potential, which is the zero point of the output signal, and an adjustment circuit that adjusts the sensitivity of the sensor device and adjusts the zero point, and the sensitivity and the zero point correct the voltage change caused by the influence of the ambient temperature Normal operation mode and non-volatile memory that outputs an electrical signal proportional to the physical quantity in the sensor circuit having a memory function for storing the temperature correction circuit and adjustment information such as the adjustment amount of the adjustment circuit and the correction amount of the temperature correction circuit. The mode transition control of the trimming operation mode for writing the adjustment information to the memory and the reading of the adjustment information to the nonvolatile memory in the trimming operation mode And to provide a physical quantity sensor manufactured at low cost can be realized inclusive can with a simple circuit.

  In order to achieve this object, the present invention is generated by electrically connecting a reference terminal provided in a physical quantity sensor to a GND terminal which is a reference potential of a sensor circuit or a power supply terminal for applying power to the circuit. By determining the overcurrent as a threshold value, transition control is performed between a normal operation mode in which an electric signal proportional to a physical quantity is output and a trimming operation mode in which adjustment information is written in a nonvolatile memory.

  Further, the reference terminal is electrically connected to a GND terminal which is a reference potential of the sensor circuit or a power supply terminal for applying power to the circuit, and the amount of overcurrent generated thereby exceeds a preset threshold value and is continuously Therefore, it is possible to prevent a malfunction of transition control due to external noise.

  Furthermore, when transition control is performed using the reference terminal, the output terminal is electrically connected from the circuit that outputs the physical quantity as an electrical signal to the circuit that writes the adjustment information to the nonvolatile memory by a switch installed in the sensor circuit. Switches. As a result, the output terminal can read and write data with a signal string composed of a general binary voltage, and the circuit can be simplified.

  Also, in normal operation mode, the circuit that writes the adjustment information to the nonvolatile memory is not electrically connected to the output terminal, so it is possible to prevent malfunction of the operation mode transition due to external noise mixed from the output terminal in the normal operation mode. Can do.

  According to the present invention, a dedicated terminal for control and writing is required in the operation mode transition control between the normal operation mode for outputting a physical quantity as an electric signal and the trimming operation mode for writing output adjustment information to the nonvolatile memory. However, it is possible to provide a physical quantity sensor that can prevent malfunction of mode transition due to noise mixed from outside, simplify the sensor circuit, and can be manufactured at low cost.

It is a block diagram of the physical quantity sensor circuit which concerns on Embodiment 1 of this invention. It is an operation example in a normal operation mode of the physical quantity sensor circuit according to the first embodiment of the present invention. It is an operation example in the trimming operation mode of the physical quantity sensor circuit according to the first embodiment of the present invention. It is an operation mode transition diagram of the physical quantity sensor circuit according to the first embodiment of the present invention. It is an operation mode transition diagram at the time of external noise influence of the physical quantity sensor circuit according to the first embodiment of the present invention. It is an example of the operation mode waveform of the physical quantity sensor circuit which concerns on Embodiment 1 of this invention. It is a block diagram of the physical quantity sensor circuit which concerns on Embodiment 2 of this invention.

  Next, an adjustment circuit using the nonvolatile memory according to Embodiment 1 of the present invention and a physical quantity sensor including the adjustment circuit will be described with reference to the drawings. In addition, embodiment described below is the illustration for demonstrating this invention, and this invention is not limited only to these embodiment. Therefore, the present invention can be implemented in various forms without departing from the gist thereof.

(Embodiment 1)
FIG. 1 is a configuration diagram of a physical quantity sensor circuit according to Embodiment 1 of the present invention.
The physical quantity sensor circuit 1 may be composed of a high-density integrated circuit using a semiconductor process in order to increase the efficiency of downsizing, mass productivity, and cost reduction.

  The voltage or current provided in the physical quantity sensor circuit 1 and generated by the sensor drive circuit 2 is supplied to the physical quantity sensor 22 electrically connected to the sensor drive terminal 18 and becomes a drive power source for the physical quantity sensor 22. The physical quantity sensor 22 may be a magnetic sensor such as a Hall element, an AMR element, a GMR element, or a TMR element, or a current sensor using the same. Alternatively, a pressure sensor using a strain gauge or the like may be used. Furthermore, it may be taken into the physical quantity sensor circuit 1 by a semiconductor process and integrated with the circuit.

  The physical quantity sensor circuit 1 includes a power supply terminal 16 and a GND terminal 17 connected to the external power supply device 23. The power supplied from the external power supply device 23 connected to the power supply terminal 16 is used as an analog circuit power supply for the physical quantity sensor circuit 1, and also has a step-down or boost function and a voltage stabilization function. 7 is used as a power source for the digital circuit of the physical quantity sensor circuit 1.

  The physical quantity sensor circuit 1 includes a sensor output terminal 19 connected to the output of the physical quantity sensor 22. The output of the physical quantity sensor 22 connected to the sensor output terminal 19 is amplified to a predetermined electric signal amount by the sensor amplification circuit unit 11 and further output from the output terminal 20 by increasing the load driving range by the buffer amplifier 12. The sensor amplification circuit unit 11 is controlled by the digital control unit 6 to adjust the amplification factor. The correction voltage generator 8 is controlled by the digital controller 6 to generate a correction voltage. The generated voltage is added to the sensor amplifier circuit unit 11 to adjust the zero point of the electrical signal output from the output terminal 20.

  The physical quantity sensor circuit 1 includes a REF voltage generation unit 9 that generates a reference voltage that is an electric signal quantity output from the output terminal 20 when the physical quantity measured by the physical quantity sensor is zero. The reference voltage generated from the REF voltage generation unit 9 is supplied to the sensor amplifier circuit unit 11 and the buffer amplifier 12. The reference voltage is a zero point potential of the electric signal amount output from the output terminal 20, and a physical quantity including positive and negative polarities can be expressed by using the reference voltage as a reference. For example, when the reference voltage is 2.5 V when the power supply voltage is 5 V, when the physical quantity changes in the positive direction, the electrical signal output from the output terminal 20 changes from 2.5 V to 5 V, and the physical quantity is negative. When the direction changes, the electrical signal output from the output terminal changes in the direction from 2.5V to 0V. Further, the reference voltage generated by the REF voltage generator 9 is output from the reference terminal 21 with the load driving range expanded by the buffer amplifier 13. Since the reference voltage output from the reference terminal 21 is always the zero point potential of the electric signal amount, the electric signal amount can be measured more accurately by comparing with the electric signal amount output from the output terminal 20. It becomes.

  The physical quantity sensor circuit 1 includes a power supply voltage measuring unit 4 that measures a power supply voltage applied from the external power supply device 23 via the power supply terminal 16. The power supply voltage measurement unit 4 functions as a power supply voltage measurement unit in a ratiometric operation in which the amount of electrical signals output from the output terminal 20 and the reference terminal 21 of the physical quantity sensor circuit 1 is proportional to the power supply voltage. Further, the digital control unit 6 controls the sensor drive circuit 2, the correction voltage generation unit 8, the REF voltage generation unit 9, and the sensor amplification circuit unit 11 according to the measured power supply voltage. The included electric signal amount has a function proportional to the power supply voltage.

  The physical quantity sensor circuit 1 includes a temperature sensor 5 that measures the ambient temperature including the physical quantity sensor circuit. Based on the temperature information of the temperature sensor 5, the digital control unit 6 controls the sensor drive circuit 2, the correction voltage generation unit 8, the REF voltage generation unit 9, and the sensor amplification circuit unit 11, thereby adjusting the sensitivity and reference voltage of the physical quantity sensor. It has a function of correcting the temperature change of the included electric signal amount.

  The physical quantity sensor circuit 1 includes a nonvolatile memory 3 connected to the digital controller 6. The nonvolatile memory 3 includes an adjustment amount of the amplification factor of the sensor amplifier circuit unit 11, a correction voltage amount of the correction voltage generation unit 8, a reference voltage amount of the REF voltage generation unit, a voltage or current amount of the sensor drive circuit 2, Furthermore, it has a function of storing the correction amount of these temperature changes.

The physical quantity sensor circuit 1 includes a current detection unit 14 that detects the current amount of the reference terminal 21. The current detection unit 14 detects the overcurrent generated in the buffer amplifier 13 and the reference terminal 21 by connecting the reference terminal 21 to the GND terminal 17 that is the reference potential of the sensor circuit or the power supply terminal 16 for applying power. And a function of determining the current amount as a threshold. When the digital control unit 6 determines that the amount of overcurrent exceeds the threshold and is continuous and has a sufficient time, the signal changeover switch 15 is switched, and the output terminal 20 is serially connected from the buffer amplifier 12. The connection to the I / F unit 10 is selected. This shifts from the normal operation mode that outputs an electrical signal proportional to the physical quantity to the trimming operation mode that writes adjustment information to the nonvolatile memory.
Furthermore, when the connection between the reference terminal 21 and the GND terminal 17 that is the reference potential of the sensor circuit or the power supply terminal 16 for applying power is released, the amount of current generated in the buffer amplifier 13 and the reference terminal 21 becomes normal. The changeover switch 15 is connected to the buffer amplifier 12 from the connection between the output terminal 20 and the serial I / F unit 10 and returns to the normal operation mode in which an electric signal proportional to the physical quantity is output. The signal changeover switch 15 for selecting this connection is controlled by the digital control unit 6 and is constituted by a three-way switch or a three-state circuit.

  FIG. 2 shows an operation example in the normal operation mode of the physical quantity sensor circuit according to the first embodiment of the present invention. In the configuration example 24 in the normal operation mode in which the reference terminal 21 is not connected to the GND terminal 17 that is the reference potential of the sensor circuit or the power supply terminal 16 for applying power, the physical quantity sensor output is always output as in the operation waveform 26. The zero point potential of the electric signal amount is output. At that time, an electrical signal proportional to the physical quantity is output from the output terminal 20 as in the operation waveform 25. At this time, since the serial I / F unit 10 is not connected to the output terminal, it is possible to prevent a malfunction in the operation mode transition caused by the external noise mixed from the output terminal 20 in the normal operation mode.

  FIG. 3 is an operation example of the trimming operation mode of the physical quantity sensor circuit according to the first embodiment of the present invention. In the trimming operation mode of the configuration example 27 in which the reference terminal 21 and the GND terminal which is the reference potential of the sensor circuit are connected by the switch 29, the overcurrent generated in the buffer amplifier 13 and the reference terminal 21 is detected by the current detection unit 14. Is done. When the amount and continuity of the overcurrent satisfy a predetermined threshold, the signal changeover switch 15 connects the output terminal 20 and the serial I / F unit 10. As a result, communication between the nonvolatile memory 3 and a higher-order trimming device that reads and writes data to and from the nonvolatile memory 3 can be performed with a signal string composed of a general binary voltage like the communication waveform 28. The circuit can be simplified.

    FIG. 4 is an operation mode transition diagram of the physical quantity sensor circuit according to the first embodiment of the present invention. According to FIG. 30, when the current detection amount of the current detection unit 14 does not exceed the mode determination threshold, the normal operation mode for outputting an electric signal proportional to the physical quantity is continuously maintained. When the current detection amount exceeds the mode determination threshold and the continuous and sufficient mode determination time is satisfied, the normal operation mode that outputs an electrical signal proportional to the physical amount is changed to the trimming operation mode that writes adjustment information to the nonvolatile memory. Transition.

  FIG. 5 is an operation mode transition diagram when the physical quantity sensor circuit according to the first embodiment of the present invention is affected by external noise. According to FIG. 31, as in FIG. 4, when the current detection amount of the current detection unit 14 does not exceed the mode determination threshold, the normal operation mode for outputting an electric signal proportional to the physical quantity is maintained. At this time, even if the external noise influence exceeds the mode determination threshold, the operation mode does not shift unless the sufficient and sufficient mode determination time is satisfied. Thereby, it is possible to prevent a malfunction of mode transition due to noise mixed from outside.

  FIG. 6 is an operation mode waveform example of the physical quantity sensor circuit according to the first embodiment of the present invention. According to the waveform example 32 of the operation mode, the waveform of the normal operation mode of the output terminal 20 outputs an electrical signal proportional to the physical quantity, the current detection amount of the current detection unit 14 exceeds the mode determination threshold, and is continuous and sufficient. When the mode determination time is satisfied, the trimming operation mode is entered. Further, since the output terminal 20 in the trimming operation mode is changed from a connection with a circuit that generates an electrical signal proportional to a physical quantity to a connection with a serial I / F unit that reads / writes data from / to a nonvolatile memory, In this communication, data can be read and written by a general signal string composed of binary voltages.

(Embodiment 2)
FIG. 7 is a configuration diagram of a physical quantity sensor circuit according to the second embodiment of the present invention.
The physical quantity sensor circuit 1 installed on the base 33 includes a shield plate 34 made of a conductive material on the upper surface thereof. The physical quantity sensor circuit 1 installed on the base 33 may be integrated with the physical quantity sensor by a semiconductor process.

Since this shield plate 34 has an effect of reducing electrical noise mixed from the outside by being electrically connected to, for example, a GND terminal having a stable potential, it is possible to further prevent malfunction of mode transition.
Furthermore, the physical quantity sensor can be improved in accuracy by reducing electrical noise mixed from the outside by the shield plate 34.

  Although the shield plate 34 has a shape that covers the entire upper surface of the physical quantity sensor circuit 1 in the drawing, it can be simplified to a shape that covers only a part of the physical quantity sensor circuit 1.

  DESCRIPTION OF SYMBOLS 1 ... Physical quantity sensor circuit, 2 ... Sensor drive circuit, 3 ... Non-volatile memory, 4 ... Power supply voltage measurement part, 5 ... Temperature sensor, 6 ... Digital control part, 7 ..Digital circuit power supply generation unit, 8... Correction voltage generation unit, 9... REF voltage generation unit, 10... Serial I / F unit, 11. Buffer amplifier, 14 ... Current detection unit, 15 ... Signal changeover switch, 16 ... Power supply terminal, 17 ... GND terminal, 18 ... Sensor drive terminal, 19 ... Sensor output terminal, 20 ... output terminal, 21 ... reference terminal, 22 ... physical quantity sensor, 23 ... external power supply, 24 ... configuration example of normal operation mode, 25, 26 ... operation waveform, 27 ... Configuration example of trimming operation mode, - communication waveforms, 29 ... switch, 30, 31 ... operation mode transition diagram, waveform example of 32 ... operation mode, 33 ... base, 34 ... shield plate

Claims (7)

Detects the reference terminal that always outputs the electric signal amount when the physical quantity measured by the physical quantity sensor is zero, the GND terminal that is the reference potential of the circuit, the power supply terminal that supplies power to the circuit, and the amount of current flowing through the reference terminal A physical detection unit that outputs a physical quantity as an electrical signal by detecting an overcurrent amount that is different from normal when the reference terminal is electrically connected to at least one of the GND terminal and the power supply terminal. A physical quantity sensor circuit that performs transition control between a normal operation mode, a trimming operation mode in which output adjustment information is written to a nonvolatile memory, and at least two operation modes. Trimming data comprising the reference terminal, the GND terminal, and the power supply terminal, the reference terminal being electrically connected to at least one of the GND terminal and the power supply terminal, and the connection being adjustment information of electrical signal output is communicated 2. The physical quantity sensor circuit according to claim 1, wherein the physical quantity sensor circuit is continuously maintained during the operation . The trimming data is written from the output terminal while the reference terminal, the GND terminal, and the output terminal are provided, and the reference terminal is continuously connected to at least one of the GND terminal and the power supply terminal. The physical quantity sensor circuit according to claim 1. 4. The physical quantity according to claim 3 , further comprising: a non-volatile memory, wherein the trimming data communication signal written to the non-volatile memory is formed of a signal string composed of binary voltages. Sensor circuit. The output terminal is provided with three or more switches or a functional component having a signal selection effect similar to that of the three or more switches, and is an output of an electrical signal proportional to a physical quantity and adjustment information of the electrical signal output 4. The physical quantity sensor circuit according to claim 3 , wherein the physical quantity sensor circuit has a function of selecting a communication signal of trimming data . Equipped with a shield plate made of conductive material, installed on the upper surface or lower surface of the physical quantity sensor circuit, or both the upper and lower surfaces, covering the entire surface or part of the physical quantity sensor circuit and reducing the noise mixed from the outside. The physical quantity sensor circuit according to claim 1, wherein the physical quantity sensor circuit is provided. A physical quantity sensor comprising the sensor circuit according to claim 1.

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