JP6019603B2 - Circuit device, integrated circuit, and detection device - Google Patents

Description

  The present invention relates to a circuit device, an integrated circuit, and a detection device. In particular, the present invention relates to a circuit device, an integrated circuit, and a detection device that are used to control a device that uses a sensor.

  Conventionally, in a detection device including a sensor, power is supplied to the sensor only during measurement to reduce power consumption. For example, in Patent Document 1, in an electronic water meter that is an example of a detection device, a low power consumption operation is realized by supplying power to a sensor only during measurement.

JP 2000-74709 A

  However, in the invention of Patent Document 1, only the sensor is intermittently operated, and the other circuits are always operating. In order to further reduce power consumption, it is preferable to intermittently operate circuits other than the sensor. For example, not only the sensor but also an amplifier circuit that receives the output signal and amplifies the signal and a conversion circuit that converts the signal of the sensor output can further reduce power consumption by performing an intermittent operation.

  When the intermittent operation is performed, the effect of reducing the power consumption is higher as the time for operating the sensor, the amplifier circuit, and the conversion circuit is shorter. For example, it is assumed that the operation time can be controlled according to the pulse width of a pulse signal used for control. At this time, it is possible to perform control for reducing power consumption as the pulse width is shorter.

  However, when a pulse signal used for control is generated in the synchronous design based on the system clock, the frequency of the system clock affects the pulse width of the pulse signal used for control. In consideration of manufacturing variations and the like, it is preferable that the pulse width of the pulse signal used for control can be easily and accurately adjusted at the time of shipment, for example.

  Further, when intermittent operation is performed, settling time is required until the operation is stabilized after the circuit is stopped and the output is stabilized. At this time, it is desirable to perform an intermittent operation in consideration of an appropriate settling time according to the characteristics of the sensor and the amplifier circuit.

  SUMMARY An advantage of some aspects of the invention is to solve at least a part of the problems or problems described above, and the invention can be implemented as the following forms or application examples.

  A circuit device according to the present invention is a circuit device including an amplifier circuit to which a signal from a sensor is input, and a control circuit that controls intermittent operation of the sensor and the amplifier circuit. The control circuit of this circuit device outputs an intermittent operation control signal to control the intermittent operation of the sensor and the amplifier circuit. According to this configuration, not only the sensor but also the amplifier circuit that receives the output signal and amplifies the signal performs an intermittent operation, so that the power consumption of the circuit device can be suppressed.

  In the above circuit device, the intermittent operation control signal includes a first intermittent operation control signal for controlling power supply of the sensor and a second intermittent operation control signal for controlling power supply of the amplifier circuit. preferable. The period in which the first intermittent operation control signal is in the active state is preferably different from the period in which the second intermittent operation control signal is in the active state.

  For example, the first intermittent operation control signal may become active after a predetermined period after the second intermittent operation control signal becomes active. In this case, the period in which the first intermittent operation control signal is in the active state can be shorter than the period in which the second intermittent operation control signal is in the active state. When the settling time from when the circuit starts operating to when the output becomes stable is compared, the settling time of the sensor composed of the resistive element is shorter than the settling time of the amplifier circuit. Therefore, by starting the intermittent operation of the sensor after a lapse of a predetermined time from the start of the intermittent operation of the amplifier circuit, the current consumption of the sensor can be reduced without affecting the stable operation of the output of the amplifier circuit. It becomes possible.

  The circuit device preferably includes a switch that can switch on and off the power supply to the sensor and the amplifier circuit. According to this configuration, the intermittent operation control signal changes the on / off state of the switch to control the power supply, whereby the power of the circuit can be reduced.

  In the above circuit device, the control circuit includes a constant current source that generates a current having a predetermined current value, a capacitor that is charged with a current from the constant current source, and a voltage based on the charge charged in the capacitor. And a comparator that outputs a pulse signal based on a result of comparing the reference voltage having a predetermined voltage value with a reference voltage.

  In the above circuit device, the pulse generation circuit may include a constant current source, a capacitor that is charged by the current, and a comparator that compares a voltage based on the charge charged in the capacitor with a reference voltage. preferable. According to this configuration, the timing of the pulse signal can be adjusted easily and accurately by changing at least one of the current value of the constant current source, the capacitance of the capacitor, and the voltage value of the reference voltage.

  The output of the comparator that compares the voltage based on the charge charged in the capacitor and the reference voltage is a pulse signal. Therefore, for example, a different pulse signal can be generated by changing the reference voltage, and a pulse signal asynchronous with the system clock can be generated.

  In the capacitor, the first terminal that is one terminal may be grounded, and the second terminal that is the other terminal may be connected in series with the constant current source. Further, the voltage based on the charge charged in the capacitor may be the voltage at the second terminal. For example, the current value of the constant current source, the capacitance of the capacitor, and the voltage value of the reference voltage may be changed in conjunction with the signal from the outside of the pulse generation circuit or individually.

  The circuit device preferably includes a pull-up transistor that pulls up an output terminal of the comparator to a high-potential power supply potential.

  In the above circuit device, the control circuit includes: a first enable signal; and a second enable signal that becomes active after a predetermined period after the first enable signal becomes active. And the first enable signal and the second enable signal are used in the pulse generation circuit, and the constant current source and the reference voltage are turned on when the first enable signal becomes active. And the comparator is set to an on state when the second enable signal becomes active, and the pull-up transistor is turned on when the second enable signal is in an inactive state. The state is preferably set.

  In the above circuit device, it is preferable that the circuit device includes a discharging transistor that discharges the charge of the capacitor when the first enable signal is in an active state and the second enable signal is in an inactive state.

  According to these configurations, by providing the pull-up transistor that pulls up the output terminal of the comparator, it is possible to prevent a signal having an indefinite level from propagating. Therefore, the constant current source that supplies the input signal of the comparator, the reference voltage, and the comparator itself can be turned off, and power consumption in the pulse generation circuit can be suppressed.

  Here, the normal signal refers to a signal having a high level on the high potential side (hereinafter, H level) or a low level on the low potential side (hereinafter, L level). An indefinite level signal means a signal of an intermediate level between these.

  At this time, for example, a first enable signal for turning on the constant current source and the reference voltage and a second enable signal for turning on the comparator may be input thereafter. The second enable signal may become active after a given time after the first enable signal becomes active. The given time may be 1 to 1023 cycles of the system clock, for example, or may be a specific time such as several ms.

  When the first and second enable signals are input, the pull-up transistor may be turned on when the second enable signal is inactive. As a result, it is possible to reliably prevent an undefined level signal from propagating.

  In the above circuit device, the pulse generation circuit further includes a discharge transistor for discharging the charge of the capacitor, and when the first enable signal is in an active state and the second enable signal is in an inactive state, It is preferable to discharge the capacitor charge by the discharging transistor. According to this configuration, the pulse generation circuit can periodically generate a pulse signal.

  In the above circuit device, it is preferable that an intermittent operation control signal for controlling the intermittent operation of the sensor and the amplifier circuit is output based on the pulse signal.

  According to this configuration, the sensor can be generated asynchronously with the system clock, and the intermittent operation control signal of the sensor and the amplifier circuit is generated using a pulse signal whose pulse width can be adjusted. In addition, the amplifier circuit can be operated, and power consumption in the sensor and the amplifier circuit can be suppressed.

  In addition, by making the above-described circuit device into a single chip and including it in an integrated circuit device, the circuit device can be reduced in size and the applicable range can be widened.

  An integrated circuit according to the present invention is an integrated circuit having a circuit device, and the circuit device includes an amplifier circuit to which a signal from a sensor is input, and a control circuit that controls the sensor and the amplifier circuit. The intermittent operation of the sensor and the intermittent operation of the amplifier circuit are controlled by an intermittent operation control signal output from the control circuit, and the intermittent operation control signal controls the intermittent operation of the sensor. A control signal and a second intermittent operation control signal for controlling the intermittent operation of the amplifier circuit, and the second intermittent operation control signal is in an active state during a period in which the first intermittent operation control signal is in an active state. It is characterized by being different from the period.

  According to this configuration, not only the sensor but also the amplifier circuit that receives the output signal and amplifies the signal performs an intermittent operation, so that the power consumption of the integrated circuit can be suppressed.

  The present invention provides a pulse generation circuit according to any one of the above, a sensor, an amplifier circuit that receives a signal from the sensor, and a measurement amount detected by the sensor based on an output signal of the amplifier circuit. A circuit for calculating, wherein the pulse generation circuit outputs a first pulse signal and a second pulse signal, and the second pulse is output during a period in which the first pulse signal is in an active state. The first intermittent operation control signal for controlling the intermittent operation of the sensor is output based on the first pulse signal, shorter than the period during which the signal is in the active state, and based on the second pulse signal, The intermittent operation may be controlled by outputting a second intermittent operation control signal for controlling the power supply of the amplifier circuit.

  The circuit device of the present invention provides an intermittent operation control signal that becomes active at different timings to the sensor and the amplifier circuit. The power consumption can be further suppressed in consideration of the output unstable time after activation of the sensor and the amplifier circuit, that is, the time until the normal signal is output.

  Specifically, it takes time until the amplifier circuit outputs a normal signal as compared with the sensor. Therefore, a first intermittent operation control signal and a second intermittent operation control signal that becomes active for a predetermined period before the first intermittent operation control signal becomes active are prepared. Then, the first intermittent operation control signal is supplied to the sensor, and the second intermittent operation control signal is supplied to the amplifier circuit.

  At this time, the period during which one intermittent operation control signal is in the active state is shorter than the period during which the other intermittent operation control signal is in the active state.

  A detection device according to the present invention includes a circuit device, a sensor, and an MCU that controls the circuit device, wherein the circuit device includes an amplification circuit to which a signal from the sensor is input, the sensor, and the amplification A control circuit for controlling the circuit, wherein the intermittent operation of the sensor and the intermittent operation of the amplifier circuit are controlled by an intermittent operation control signal output from the control circuit, and the intermittent operation control signal is Including a first intermittent operation control signal for controlling the intermittent operation and a second intermittent operation control signal for controlling the intermittent operation of the amplifier circuit, and a period during which the first intermittent operation control signal is in an active state, The second intermittent operation control signal is different from a period in which the second intermittent operation control signal is in an active state.

  According to this configuration, accurate measurement is possible even when there are manufacturing variations and operating environment changes, and the power consumption of the detection device is also suppressed by operating the circuit device of the present invention while stopping the operation of the MCU. It is possible.

  The MCU (Micro Controller Unit) is, for example, a processor and may include a memory such as a ROM or a RAM, an interface-related peripheral function, or the like. In addition, the MCU may control the circuit device and may, for example, integrate the measurement amounts detected by the sensors and display the results on a display unit or the like.

The example of the circuit diagram of the pulse generation circuit of 1st Embodiment. (A)-(B) is a figure which shows the behavior to the normal output start in intermittent operation | movement. FIG. 4 is a waveform diagram of an output pulse signal and the like according to the first embodiment. (A) is a top view of the flow path in which the rotation detection device is installed. (B) is the fragmentary sectional view. A circuit device and a detection device including the pulse generation circuit of the first embodiment. The example of the circuit diagram of the pulse generation circuit of 2nd Embodiment. The waveform diagram of the output pulse signal etc. of 2nd Embodiment. A circuit device and a detection device including the pulse generation circuit of the second embodiment. The figure showing the structural example of a comparator.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. It should be noted that the drawings used for explanation are for convenience of explanation, and do not describe all the components necessary for configuring the apparatus.

1. 1st Embodiment 1st Embodiment of this invention is described with reference to FIGS. 1-5, FIG. Below, the pulse generator circuit of 1st Embodiment is demonstrated first, and the circuit apparatus and detection apparatus containing the pulse generator circuit of 1st Embodiment are demonstrated after that.

1.1. Configuration of Pulse Generation Circuit According to this Embodiment FIG. 1 is a circuit diagram of a pulse generation circuit 20 according to this embodiment. The pulse generation circuit 20 includes a constant current source 32, a capacitor 36, and a comparator 40.

  The constant current source 32 allows a current having a predetermined current value to flow when the transmission gate 34 is on.

  One terminal (first terminal) of the capacitor 36 is grounded, and the other terminal (second terminal) is connected to the constant current source 32 via the transmission gate 34. Therefore, when the transmission gate 34 is in the ON state, the capacitor 36 is gradually charged.

  A second terminal of the capacitor 36 is connected in parallel to the transmission gate 38. When the transmission gate 38 is turned on, the capacitor 36 is discharged. That is, since the transmission gate 38 is a discharge transistor, it will be referred to as a discharge transistor 38 below.

The comparator 40 compares the level of the charge voltage 130, which is a voltage based on the charge charged in the capacitor 36, with the reference voltage 42. In the present embodiment, the reference voltage 42 takes a predetermined voltage value V _R. For example, when the charge voltage 130 is less than the voltage value V _R , the comparator output signal 126 becomes L level. Then, the output pulse signal 120 obtained by inverting the signal by the inverter 48 becomes H level.

  The output terminal of the comparator 40 is connected to the transmission gate 44. Comparator output signal 126 is pulled up to an H level when transmission gate 44 is in an on state. That is, since the transmission gate 44 is a pull-up transistor, it will be referred to as a pull-up transistor 44 below.

  Here, in order to reduce power consumption, the pulse generation circuit 20 may include an element that is turned off when not used. In the present embodiment, the constant current source 32 and the reference voltage 42 are turned on by a pulse power supply enable signal 124 that is a first enable signal. The pulse power supply enable signal 124 is a signal that becomes active when the pulse generation circuit 20 is used.

  In the present embodiment, the comparator 40 is turned on by the pulse generation enable signal 122 that is the second enable signal. The pulse generation enable signal 122 becomes active after a given period (for example, several cycles of the system clock) after the pulse power supply enable signal 124 becomes active. Thereby, after sufficient setup time, the output from the comparator 40 (that is, the output of the output pulse signal 120) is started.

  The pulse generation circuit 20 of this embodiment includes a flip-flop composed of NAND circuits 60 and 62 and an inverter 64. The output of this flip-flop is inverted by an inverter 66. This flip-flop holds a value corresponding to the combination of the pulse generation enable signal 122 and the output pulse signal 120. The capacitor 36 is charged or discharged according to the value held by the flip-flop.

  For example, when the output value of the inverter 66 is H level, the transmission gate 34 is turned on, and the capacitor 36 is charged with electric charge. Conversely, when the output value of the inverter 66 is L level and the output of the flip-flop is H level, the discharging transistor 38 is turned on, and the capacitor 36 discharges electric charge.

  In this embodiment, the pull-up transistor 44 is controlled by the pulse generation enable signal 122. When the pulse generation enable signal 122 is in an inactive state (here, L level), the comparator 40 is in an off state, and therefore, it is necessary to pull up its output terminal. In the pulse generation circuit 20 of the present embodiment, the pulse generation enable signal 122 is inverted by the inverter 46 and connected to the pull-up transistor 44 to realize this operation.

1.2. Regarding Output of Comparator in Intermittent Operation FIGS. 2A to 2B are diagrams for explaining the operation in the intermittent operation of the comparator CMP. The intermittent operation of the comparator leads to suppression of power consumption. FIG. 2A shows the configuration of the comparator CMP. In addition to an inverting input terminal to which the signal V _INN is input, a non-inverting input terminal to which the signal V _INP is input, and an output terminal to output the output signal V _OUT , an enable terminal that receives the enable signal EN is provided. When the enable signal EN is at L level, for example, the comparator does not operate (OFF state), and no power is supplied, so no power is consumed.

However, when the comparator CMP is turned off, an undefined level signal may propagate as the output signal V _OUT . In addition, when the comparator CMP is activated, it takes a certain time to output a normal signal. That is, there is an output unstable time after the comparator CMP is started.

FIG. 2B is an example of the output signal V _OUT of the comparator CMP. When the enable signal EN changes from L level to H level, the comparator CMP is activated. However, the output signal V _OUT is outputting an indefinite level signal until it is activated. After the start-up, there is an output unstable time t _idle until the output signal V _OUT outputs an H level which is a normal signal. When intermittent operation is performed in a circuit including a comparator, it is necessary to consider a period during which a normal signal is not output. Note that the voltage applied to the input terminal in this example is V _INP > V _INN .

  For example, in the pulse generation circuit 20 of FIG. 1, the on / off state of the comparator 40 is switched by the pulse generation enable signal 122. A pull-up transistor 44 is provided so that an indefinite level signal does not propagate when the comparator 40 is in the OFF state.

  For example, in a detection device including a sensor, the output of an amplifier circuit that receives an analog signal from the sensor may be sampled. At this time, it is necessary to consider that the output unstable time fluctuates due to, for example, manufacturing variations. Therefore, the pulse signal that gives the sampling timing needs to be very accurate so that appropriate data can be acquired even if the output unstable time varies.

  Here, an accurate timing is given if it is a pulse signal synchronized with the system clock, but sampling takes time when the frequency of the system clock is low. For this reason, the detection performance of the detection device is deteriorated, and the time during which the sensor or the like is activated becomes longer, so the effect of suppressing power consumption is lost.

  Therefore, the pulse signal that gives the timing for sampling the output of the amplifier circuit is required to be asynchronous to the system clock and accurate. The pulse generation circuit of the present embodiment changes the timing of the pulse signal easily and asynchronously with the system clock by changing at least one of the current value of the constant current source, the capacitance of the capacitor, and the voltage value of the reference voltage. It can be adjusted accurately.

Here, it is assumed that the comparator of the present embodiment has a configuration as shown in FIG. 9, for example. The comparator 40 of this embodiment includes two N-type transistors that receive a non-inverting input V _INP and an inverting input V _INN , two P-type transistors that form a current mirror circuit, a non-inverting input V _INP and an inverting input V _INN . A P-type transistor that functions as a switch in accordance with the magnitude relationship between and a constant current source are connected as shown in FIG.

  The comparator 40 of the present embodiment has a small slew rate when the comparator output signal 126 changes from H level to L level. Therefore, the effects of low power consumption and circuit scale reduction can be obtained.

Here, the comparator output signal 126 changes gradually from the H level to the L level (refer to the change of the comparator output signal 126 at times t _{1 to} t ₃ in FIG. 3). For this reason, a through current may flow in the inverter 48 (see FIG. 1) in the subsequent stage, but the through current can be reduced by designing the gate length to be long. Therefore, the use of the comparator 40 of FIG. 9 provides the effect of reducing the power consumption and the circuit scale of the pulse generation circuit 20.

1.3. Waveform Diagram FIG. 3 is a waveform diagram of the pulse generation circuit of this embodiment. With reference to FIG. 3, it will be described that the timing of the output pulse signal 120 can be adjusted easily and accurately. In addition, the same code | symbol is attached | subjected to the same signal as FIG. 1, and description is abbreviate | omitted.

  The system clock in FIG. 3 is a clock used by a system including a pulse generation circuit and a pulse generation circuit here. The pulse generation circuit generates an output pulse signal 120 that is asynchronous with the system clock.

First, at time t ₀ , the pulse power supply enable signal 124 is activated, and the constant current source 32 and the reference voltage 42 in FIG. 1 are turned on. Then, the period T _{0 corresponding} to one cycle of the system clock is set as the setup period, and the pulse generation enable signal 122 becomes active at the subsequent time t ₁ .

The comparator 40 (see FIG. 1) is activated by the pulse generation enable signal 122. At time t ₁ , the comparator output signal 126 is at the H level due to the influence of the pull-up transistor 44 (see FIG. 1) that was on until just before.

When the pulse generation enable signal 122 changes to H level, the comparator 40 starts operating. At time t ₁ , the charge voltage 130 is L level and lower than the reference voltage (V _R ), so the comparator output signal 126 gradually changes to L level, and at time t ₂ , the output pulse signal 120 changes to H level. Let Then, the flip-flop output is changed, the transmission gate 34 is turned on, and the charge voltage 130 starts to rise.

The comparator 40 (see FIG. 1) compares the charge voltage 130 with the reference voltage (V _R ). Then, the charge voltage 130 comparator output signal 126 at time t ₃ when exceeding the reference voltage (V _R) is changed to the H level. Then, the output pulse signal 120 is inverted to L level. This timing is independent of, for example, the time t _{4 when the} system clock falls. Therefore, the pulse generation circuit can output the output pulse signal 120 asynchronous with the system clock.

Thus, in the pulse generation circuit of this embodiment, the timing of the output pulse signal 120 is determined by the relationship between the charge voltage 130 and the reference voltage (V _R ). Therefore, an accurate pulse signal can be generated by adjusting at least one of the current value of the constant current source that determines the change of the charge voltage 130 and the capacitance of the capacitor at the time of shipment, for example. Also, by adjusting the voltage value V _R of the reference voltage, it is possible to generate an accurate pulse signal.

  Since the pulse generation circuit of this embodiment can generate a pulse signal that can be adjusted easily and accurately asynchronously with the system clock, it can be applied to a detection device or the like as described later. For example, in a detection device including a sensor, an intermittent operation control signal (intermittent operation control signal 222) for turning on the power of the sensor and the amplifier circuit may be used. At this time, by generating the intermittent operation control signal 222 based on the output pulse signal 120, the sensor or the like can be turned on only when necessary, and power consumption can be suppressed.

At this time, if the amplifier circuit is a comparator, each detection device may have a different output unstable time. As a result, an accurate pulse signal that gives the timing of the period T ₁ during which the sensor output sampling signal 200 is sufficiently stable is required while leaving the sufficient hold period T ₂ .

  In the pulse generation circuit of this embodiment, the timing of the pulse signal can be easily and accurately adjusted by changing at least one of the current value of the constant current source, the capacitance of the capacitor, and the voltage value of the reference voltage. Therefore, it can be suitably applied to a detection device or the like as will be described later.

  The intermittent operation control signal 222 and the sensor output sampling signal 200 correspond to signals having the same reference numerals in the block diagram of FIG.

1.4. Operation of Rotation Detection Device Here, a rotation detection device that is one of the detection devices will be described with reference to FIGS. 4 (A) to 4 (B). 4A is a top view of a flow path in which the rotation detection device is installed, and FIG. 4B shows a partial cross-sectional view thereof. In FIG. 4A, a magnetic sensor that is one of the sensors is not shown.

  In the rotation detection device, the amount to be measured (measured amount) is replaced with the rotation speed, and the rotation speed is detected by, for example, a magnetic sensor and an electric signal is output. The electric signal is processed by, for example, an MCU to obtain a measured amount. The amount to be measured may be a flow rate of a liquid such as water or a flow rate of a gas such as gas. Below, the rotation detection apparatus which measures the flow volume of a liquid is demonstrated. For example, the liquid is water, which can be applied to a water meter.

  In FIG. 4A, the impeller 100 is installed in the liquid flow path 104. When the liquid flows in the direction of the arrow X1, the impeller 100 rotates clockwise as indicated by the arrow X2. The liquid flow rate can be determined by measuring the number of rotations. Here, a magnet 102 is attached to the shaft of the impeller 100, and the magnetism changes as the impeller 100 rotates.

  FIG. 4B is a cross-sectional view of the liquid flow path 104 in FIG. Near the impeller 100, a magnetic sensor 106 is attached to the substrate 108 and installed. At this time, the magnetic sensor 106 is not in contact with the impeller 100. The magnetic sensor 106 detects magnetism that is changed by the magnet 102 when the impeller 100 rotates. Then, an electric signal is output based on the detection result, and for example, an MCU (not shown) attached to the substrate 108 receives the signal and calculates the rotation speed. The MCU also calculates the liquid flow rate based on the number of rotations.

  For example, a rotation detection device such as a water meter may be driven by a battery. Therefore, there is a strong demand for reducing power consumption in order to operate with a battery for a long period of time. For accurate measurement, the output of the sensor needs to be sampled at an appropriate timing. Therefore, by incorporating the pulse generation circuit of this embodiment as a detection device or a circuit device including a detection circuit, accurate sampling can be performed with low power consumption as described later.

1.5. Circuit Device and Detection Device FIG. 5 shows a circuit device 2 and a detection device 1 including the pulse generation circuit 20 of the present embodiment. The same components as those in FIGS. 1 and 3 are denoted by the same reference numerals and description thereof will be omitted. The detection device 1 of the present embodiment is the rotation detection device described above, but is not limited to this.

  As shown in FIG. 5, the pulse generation circuit 20 is included in the control circuit 10. At this time, the control circuit 10 may be integrated into one chip as the circuit device 2 together with the sensor 70, the amplifier circuit 72, and the transmission gate 76 to form an integrated circuit device. The transmission gate 76 operates as a switch circuit. This switch circuit may adopt other circuit configurations.

  The sensor 70 is a magnetic sensor that detects a change in magnetism. Hereinafter, the sensor 70 is expressed as a sensor. The amplifying circuit 72 receives the output of the sensor, converts it into a sensor output sampling signal 200, and outputs it. The amplifier circuit 72 may use an operational amplifier. The amplifier circuit 72 may be a comparator. A plurality of sensors and amplifier circuits may be included.

  The circuit device 2 intermittently operates not only the sensor but also the amplifier circuit in order to suppress power consumption. At this time, the control circuit 10 controls the intermittent operation to the sensor and the amplifier circuit by switching the transmission gate between the on state and the off state by the intermittent operation control signal 222. In the present embodiment, the transmission gate 76 is turned on only when the intermittent operation control signal 222 is 1, and a valid signal of the sensor output sampling signal 200 is input to the control circuit 10. In addition to this, not only the sensor but also the amplifier circuit does not consume power, so the power consumption can be reduced.

  At this time, the control circuit 10 generates an intermittent operation control signal 222 based on the output pulse signal 120 from the pulse generation circuit 20, and samples the sensor output sampling signal 200 based on the output pulse signal 120 (see FIG. 3). .

  Since the sensor or the like can be turned on for a minimum necessary time for sampling data from the sensor, it is possible to reduce power consumption. Further, in the pulse generation circuit 20 of this embodiment, the timing of the output pulse signal 120 is easily and accurately adjusted by changing at least one of the current value of the constant current source, the capacitance of the capacitor, and the voltage value of the reference voltage. Is possible. Therefore, sampling can be performed when the sensor output sampling signal 200 is sufficiently stable.

  Here, the detection device 1 includes an MCU 3 in addition to the circuit device 2. The circuit device 2 may output an interrupt signal 211 in response to rotation or rotation stop. The MCU 3 may obtain, for example, an integrated value of the flow rate using a counter or the like based on the interrupt signal 211. A plurality of interrupt signals 211 may be prepared according to forward rotation, reverse rotation, rotation stop, and the like.

  In the detection apparatus 1, the control circuit 10 provides the pulse power supply enable signal 124 and the pulse generation enable signal 122 to the pulse generation circuit 20 based on the control signal 201 from the MCU 3.

  Thus, the pulse generation circuit of this embodiment can be suitably applied to the detection device 1 and its circuit device 2 because the timing of the pulse signal can be adjusted easily and accurately.

2. Second Embodiment A second embodiment of the present invention will be described with reference to FIGS. In the circuit device of the second embodiment, by generating and outputting a plurality of intermittent operation control signals, it is possible to further reduce power consumption when applied to the detection device 1 or the like. The number of intermittent operation control signals may be three or more, but in this embodiment, it is assumed that there are two.

2.1. Configuration of Pulse Generation Circuit According to this Embodiment A pulse generation circuit according to this embodiment will be described with reference to FIG. FIG. 6 is a circuit diagram of the pulse generation circuit 20A of the present embodiment. The same elements as those in FIGS. 1 to 5 are denoted by the same reference numerals and description thereof is omitted.

  The pulse generation circuit 20A includes two comparators 40A and 40B. The first comparator output signal 126A and the second comparator output signal 126B that are the respective outputs are the first output pulse signal 120A and the second pulse signal that are the first pulse signals via the logic circuit, respectively. A certain second output pulse signal 120B is output.

Here, the two comparators 40A and 40B compare the levels of the charge voltage 130 and the reference voltage. Here, the two comparators 40A and 40B use different reference voltages (first reference voltage 42A and second reference voltage 42B), respectively. For example, the voltage value of the first reference voltage 42A of the comparator 40A may be V _R0, and the voltage value of the second reference voltage 42B of the comparator 40B may be V _R1 (> V _R0 ).

  In the present embodiment, the second output pulse signal 120B is obtained by inverting the second comparator output signal 126B by the inverter 48. The first output pulse signal 120A is an output signal of the AND circuit 49 that receives the second output pulse signal 120B and the first comparator output signal 126A. Thus, it is possible to generate an output pulse signal by combining a plurality of signals.

  Here, the comparators 40A and 40B may also be configured as shown in FIG. 9, for example. In the present embodiment, since the two comparators 40A and 40B are used, the first output pulse signal 120A and the second output pulse signal 120B can be output.

  The pulse generation circuit 20A of this embodiment can output two pulse signals having different timings. For example, if a plurality of intermittent operation control signals are generated based on these, the intermittent operation can be performed without waste for each circuit to which the signals are supplied, and further power consumption can be suppressed.

  Note that pull-up transistors 44A and 44B, which are transmission gates, are also connected to the output terminals of the two comparators 40A and 40B. This prevents an undefined level signal from propagating. The pull-up transistors 44A and 44B are turned on when the signals obtained by inverting the pulse generation enable signal 122 by the inverters 46A and 46B are at the H level.

2.2. Waveform Diagram FIG. 7 is a waveform diagram of the pulse generation circuit of this embodiment. In addition, the same code | symbol is attached | subjected to the same signal as FIG.1, FIG.3, FIG.6, and description is abbreviate | omitted.

  The pulse generation circuit generates output pulse signals 120A and 120B that are asynchronous with the system clock.

Similar to the first embodiment (FIG. 3), at time t ₁ , the first comparator output signal 126A and the second comparator are affected by the pull-up transistors 44A and 44B (see FIG. 6) that were on until just before. The oscillator output signal 126B is at the H level.

When the pulse generation enable signal 122 changes to H level, the comparators 40A and 40B start operating. Since the second reference voltage 42B is higher than the L level of the charge voltage 130 voltage, the second comparator output signal 126B is gradually changed to the L level, the second output pulse signal 120B at time t ₂ H Change to level. Then, the transmission gate 34 is turned on and the charge voltage 130 starts to rise.

Then, the charge voltage 130 is first comparator output signal 126A is changed to H level at time t _2A beyond the first reference voltage (V _R0). Then, the first output pulse signal 120A changes to the H level.

At time t ₃ when the charge voltage 130 exceeds the second reference voltage (V _R1 ), the second comparator output signal 126B also changes to H level. At this time, both the first output pulse signal 120A and the second output pulse signal 120B change to the L level.

  As described above, two different output pulse signals (first output pulse signal 120A, second output signal) are generated by passing through the AND circuit 49 of FIG. An output pulse signal 120B) is generated.

  If an intermittent operation control signal is generated based on each of these output pulse signals 120A and 120B, an intermittent operation can be performed without waste for each circuit, and power consumption can be further suppressed.

Specifically, for a circuit that takes time until a normal signal is output, the first intermittent operation control signal 222A that becomes active early is supplied. For a circuit (for example, a sensor) that outputs a normal signal immediately, the second intermittent operation control that becomes active after a predetermined period T ₄ after the first intermittent operation control signal 222A becomes active. Signal 222B is provided.

  In the present embodiment, the first intermittent operation control signal 222A is a second intermittent operation control signal generated based on the second output pulse signal 120B, and the second intermittent operation control signal 222B is the first output pulse signal 120A. It is the 1st intermittent operation control signal generated based on this.

2.3. Circuit Device and Detection Device FIG. 8 shows a circuit device 2A and a detection device 1A including the pulse generation circuit 20A of the present embodiment. The same elements as those in FIGS. 1, 3, and 5 to 7 are denoted by the same reference numerals and description thereof will be omitted. The detection device 1A of the present embodiment is a rotation detection device as in the first embodiment, but is not limited thereto.

  As shown in FIG. 8, the control circuit 10A of the present embodiment includes a pulse generation circuit 20A and may be used as a part of the detection apparatus 1A. At this time, the amplifier circuit 72, the transmission gates 76A and 76B, and the control circuit 10A may be an integrated circuit formed as a single chip as the circuit device 2A.

  The pulse generation circuit 20A outputs two pulse signals (first output pulse signal 120A and second output pulse signal 120B) having different timings to the control circuit 10A. Then, as described above, the control circuit 10A generates the first intermittent operation control signal 222A based on the second output pulse signal 120B, and generates the second intermittent operation control signal 222B based on the first output pulse signal 120A. .

As shown in FIG. 2B, the amplifier circuit 72 has an output unstable time t _idle at the time of activation, and even if the sensor is operating during this time, correct data is not transmitted to the control circuit 10A. In other words, settling time is required until the output is stabilized. When the settling time of the sensor is shorter than the settling time of the amplifier circuit 72, the power consumption can be kept lower by turning the sensor off during the output unstable time t _idle of the amplifier circuit 72. .

  Therefore, by preparing the first intermittent operation control signal 222A and the second intermittent operation control signal 222B, the timing at which the amplifier circuit and the sensor are turned on is changed to suppress the power consumption of the detection apparatus 1A.

More specifically, the first intermittent operation control signal 222A is input to the transmission gate 76A, activating the amplification circuit 72 based on the timing of time t ₂ in FIG. On the other hand, the second intermittent operation control signal 222B is inputted to the transmission gate 76B, to activate the sensor based on the timing of time t _2A of FIG. At this time, since the sensor is not activated during the output unstable time of the amplifier circuit 72, there is no waste as the operation of the detection apparatus 1A, and power consumption can be suppressed.

The present invention is not limited to these exemplifications, and includes configurations that are substantially the same as the configurations described in the embodiments (for example, configurations that have the same functions, methods, and results, or configurations that have the same objects and effects).
For example, the case where the settling time of the sensor is shorter than the settling time of the amplifier circuit 72 has been described. Conversely, when the settling time of the sensor is longer than the settling time of the amplifier circuit 72, the intermittent operation of the sensor is started. The intermittent operation of the amplifier circuit 72 can be started after a predetermined time has elapsed.

For example, although the present embodiment and the modification have been described using the magnetic sensor, the pressure sensor, the illuminance sensor, and the temperature sensor may be used instead of the magnetic sensor.
The amplifier circuit 72 may use an operational amplifier, a comparator, and an analog / digital conversion circuit.
For example, the transmission gates 76, 76A and 76B control intermittent operation as power supply switches, but sensors or amplifier circuits having the functions of these switches may be used. Alternatively, the MCU may include the control circuit 10, the control circuit 10A, the circuit device 2, or the circuit device 2A.

  In addition, the invention includes a configuration in which a non-essential part of the configuration described in the embodiment is replaced. In addition, the present invention includes a configuration that exhibits the same operational effects as the configuration described in the embodiment or a configuration that can achieve the same object. Further, the invention includes a configuration in which a known technique is added to the configuration described in the embodiment. The present invention can be widely applied without departing from the spirit of the present invention.

  DESCRIPTION OF SYMBOLS 1 ... Detection apparatus, 1A ... Detection apparatus, 2 ... Circuit apparatus, 2A ... Circuit apparatus, 3 ... MCU, 10 ... Control circuit, 10A ... Control circuit, 20 ... Pulse generation circuit, 20A ... Pulse generation circuit, 32 ... Constant current Source 34 ... Transmission gate 36 ... Capacitor 38 ... Transmission gate (discharge transistor) 40 ... Comparator 40A ... Comparator 40B ... Comparator 42 ... Reference voltage 42A ... First reference voltage 42B ... second reference voltage, 44 ... transmission gate (pull-up transistor), 44A ... transmission gate (pull-up transistor), 44B ... transmission gate (pull-up transistor), 46 ... inverter, 46A ... inverter, 6B ... Inverter, 48 ... Inverter, 49 ... AND circuit, 60 ... NAND circuit, 62 ... NAND circuit, 64 ... Inverter, 66 ... Inverter, 70 ... Sensor, 72 ... Amplifier circuit, 76 ... Transmission gate, 76A ... Transmission gate, 76B ... Transmission gate, 100 ... Impeller, 102 ... Magnet, 104 ... Flow path, 106 ... Magnetic sensor, 108 ... Substrate, 120 ... Output pulse signal, 120A ... First output pulse signal, 120B ... Second output pulse signal, 122 ... Pulse generation enable signal, 124 ... Pulse power supply enable signal, 126 ... Comparator output signal, 126A ... First comparator output signal, 126B ... Second comparator output signal, 130 ... Charge voltage, 200 ... Sensor output sampling No., 201 ... control signal, 211 ... interrupt signal, 222 ... intermittent operation control signal, 222A ... first intermittent operation control signal, 222B ... second intermittent operation control signal.

Claims (8)

An amplifier circuit to which a signal from the sensor is input;
A control circuit for controlling the sensor and the amplifier circuit;
Including
The intermittent operation of the sensor and the intermittent operation of the amplifier circuit are controlled by an intermittent operation control signal output from the control circuit,
The control circuit includes a pulse generation circuit,
The pulse generation circuit includes:
A constant current source for generating a current of a predetermined current value;
A capacitor whose charge is charged by the current from the constant current source;
A comparator that outputs a pulse signal based on a result of comparing a voltage based on the charge charged in the capacitor and a reference voltage having a predetermined voltage value;
A pull-up transistor for pulling up the output terminal of the comparator to the power supply potential on the high potential side;
Including
The pulse generation circuit generates a first enable signal and a second enable signal that becomes active after a predetermined period after the first enable signal becomes active;
The constant current source and the reference voltage are set to an on state when the first enable signal becomes an active state,
The comparator is set to an on state by the second enable signal becoming an active state,
The circuit device according to claim 1, wherein the pull-up transistor is set to an on state when the second enable signal is in an inactive state. The sensor is composed of a resistance element,
2. The circuit device according to claim 1, wherein a settling time of the sensor is shorter than a settling time of the amplifier circuit. Intermittent operation before Symbol sensor is controlled by a first intermittent operation control signal output from the control circuit,
The intermittent operation of the amplifier circuit is controlled by a second intermittent operation control signal output from the control circuit,
3. The circuit device according to claim 1 , wherein the first intermittent operation control signal becomes active after a predetermined period after the second intermittent operation control signal becomes active. 4. A switch capable of switching on and off of power supply to the sensor and the amplifier circuit;
4. The circuit device according to claim 3, wherein the first intermittent operation control signal and the second intermittent operation control signal are output to the switch and used for controlling on / off switching of the power supply. 5. The pulse generation circuit further includes a discharge transistor,
When the first of said enable signal is and active second enable signal is inactive, claims 1 to 4 charges charged in the capacitor by the discharge transistor is characterized in that it is discharged The circuit device according to any one of the above. 5. The circuit device according to claim 3 , wherein the control circuit generates the first intermittent operation control signal and the second intermittent operation control signal based on the pulse signal. 6. Integrated circuit, characterized in that it comprises a circuit device according to any one of claims 1 to 6. A circuit device according to any one of claims 1 to 6 ,
The sensor;
An MCU for controlling the circuit device;
A detection device comprising:

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