JP2014236458A - Semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reconcile a reduced power consumption of an analog front end circuit for converting an output of an analog signal output circuit to a digital signal and a stable operation of the analog front end circuit, irrespective of the type of the analog signal output circuit.SOLUTION: An operational amplifier 120 in an analog front end circuit 110 includes a differential stage 130 disposed on an input side of an analog signal SI. A control section 180 controls a voltage range of the analog signal SI acceptable to the differential stage 130. As to the control, the control section 180 can switch between a first control method based on a voltage of the analog signal SI and a second control method based on a supply voltage V0 of an analog signal output circuit for outputting the analog signal SI to the differential stage 130.

Description

  The present invention relates to a semiconductor device, for example, an analog front-end circuit that converts an analog signal into a digital signal.

  An analog front-end circuit for converting the sensor measurement result (analog signal) into a digital signal is required between an analog signal output circuit such as a sensor and a digital circuit that processes the sensor measurement result. An operational amplifier is often used as an input stage of such an analog front-end circuit.

  The operational amplifier usually includes a differential stage provided on the input side and an output stage provided on the output side for amplifying the output of the differential stage. The voltage range (hereinafter referred to as “input range”) of the analog signal input to the operational amplifier that can be supported by the operational amplifier is limited to the voltage of the operation power supply of the differential stage.

  The operational amplifier disclosed in Patent Document 1 (for example, claim 4, FIG. 4) applies the predetermined power supply voltage as a power source to the differential stage when the input voltage does not reach the vicinity of the predetermined power supply voltage. On the other hand, when the input voltage reaches the vicinity of the predetermined power supply voltage, a voltage higher than the predetermined power supply voltage is applied to the differential stage as a power source. That is, the operational amplifier can adjust the input range that can be handled by the above configuration, and can reduce the power consumption of the operational amplifier.

JP 2005-33558 A

  There are various types of sensors, and there are various modes of analog signals output from the sensors and input to the operational amplifier of the analog front-end circuit.

  For example, in the case of a temperature sensor, since the temperature rarely changes rapidly, the output voltage of the temperature sensor usually has a small fluctuation like a DC voltage. On the other hand, when a fluctuating physical quantity such as a flow rate is detected by a bridge sensor, the output voltage varies greatly like an AC voltage.

  When the operational amplifier described in Patent Document 1 is provided in an analog front-end circuit for an analog signal output circuit with a small output voltage variation such as a temperature sensor, the input voltage variation of the operational amplifier is small. Therefore, the input range that can be handled by the operational amplifier can be adjusted appropriately.

  On the other hand, when the operational amplifier described in Patent Document 1 is provided in an analog front-end circuit for an analog front-end circuit having a large output voltage variation, such as a flow rate sensor using a bridge sensor, during the A / D conversion. There is a high possibility that the power supply voltage of the differential stage is switched, and there is a possibility that stable operation of the analog front-end circuit cannot be realized.

  Other problems and novel features will become apparent from the description of the specification and the accompanying drawings.

  A semiconductor device according to an embodiment includes a differential stage to which an analog signal is input and a control unit that controls an input range that can be handled by the differential stage.

  When controlling the differential stage, the control unit controls the first control method based on the voltage of the analog signal input to the differential stage, and the operation of the analog signal output circuit that outputs the analog signal to the differential stage. The second control method based on the power supply voltage can be switched.

  Note that a representation obtained by replacing the semiconductor device of the above embodiment with a method or a system, an electronic device including the semiconductor device, or the like is also effective as an embodiment.

  According to the semiconductor device of the embodiment, the power consumption of the analog front end circuit for converting the output of the analog signal output circuit into a digital signal is reduced regardless of the type of the analog signal output circuit, and the analog front It is possible to achieve both stable operation of the end circuit.

1 is a diagram illustrating a semiconductor device according to a first embodiment. It is a figure which shows the semiconductor device concerning 2nd Embodiment. 3 is a diagram illustrating a circuit configuration example of a differential stage and an output stage of an analog front end circuit in the semiconductor device shown in FIG. It is a figure which shows the semiconductor device concerning 3rd Embodiment. It is a figure which shows the semiconductor device concerning 4th Embodiment. It is a figure which shows the semiconductor device concerning 5th Embodiment. It is a figure which shows the semiconductor device concerning 6th Embodiment.

  For clarity of explanation, the following description and drawings are omitted and simplified as appropriate. Moreover, in each drawing, the same code | symbol is attached | subjected to the same element and duplication description is abbreviate | omitted as needed.

<First Embodiment>
FIG. 1 shows a semiconductor device 100 according to the first embodiment. The semiconductor device 100 includes an analog front end circuit 110, a control unit 180, and a monitor circuit 190.

  The analog front end circuit 110 is a circuit for converting an input analog signal SI into a digital signal, and includes an operational amplifier 120 and an A / D converter (hereinafter referred to as “ADC”) 160.

  The operational amplifier 120 includes a differential stage 130 to which an analog signal SI is input, and an output stage 150 that amplifies the output of the differential stage 130 and supplies the amplified signal to the ADC 160.

The control unit 180 controls a corresponding input range for the differential stage 130.
In the present embodiment, the control unit 180 can switch between two control methods when controlling the differential stage 130.

  The first control method is a control method based on the voltage of the analog signal SI. In this case, the control unit 180 performs control based on the voltage of the analog signal SI measured by the monitor circuit 190.

  The second control method is a control method based on the voltage of the operating power supply of an analog signal output circuit (not shown) that outputs the analog signal SI. In this case, the control unit 180 performs control based on the power supply voltage V 0 of the analog signal output circuit measured by the monitor circuit 190.

For example, the semiconductor device 100 may be operated as follows.
The control unit 180 determines which one of the first control method and the second control method is adopted based on the type of the analog signal output circuit that outputs the analog signal SI.

  For example, when analog front-end circuits are classified according to the magnitude of fluctuations in the output voltage, an analog signal output circuit such as a temperature sensor whose output voltage is as small as a DC voltage and a bridge sensor are used. The analog signal output circuit having a large variation in output voltage such as an AC voltage, such as a flow rate sensor, is classified into a different type. Hereinafter, the former and the latter are referred to as a “first type analog signal output circuit” and a “second type analog signal output circuit”, respectively.

  When the analog signal output circuit that outputs the analog signal SI is the first type analog signal output circuit, the monitor circuit 190 measures the voltage of the analog signal SI and outputs the voltage to the control unit 180. The control unit 180 uses the first control method to control the input range that can be handled by the differential stage 130 based on the voltage of the analog signal SI measured by the monitor circuit 190.

  At this time, if the voltage of the analog signal SI is large, the control unit 180 performs control so that the input range that can be handled by the differential stage 130 is expanded. Thus, even if the voltage of the analog signal SI is large, the analog front end circuit 110 can appropriately process the analog signal SI.

  If the voltage of the analog signal SI is small, the control unit 180 controls to reduce the input range that can be handled by the differential stage 130. By doing so, the power consumption of the differential stage 130 can be reduced under the premise that the analog front-end circuit 110 can appropriately process the analog signal SI.

  Since the variation of the voltage of the analog signal SI is small, even if the compatible input range of the differential stage 130 is controlled according to the voltage of the analog signal SI, the differential stage during the A / D conversion of the analog signal SI Since the 130 compatible input ranges are not changed, stable operation of the analog front-end circuit 110 can be ensured.

  On the other hand, when the analog signal output circuit is the second type analog signal output circuit, the monitor circuit 190 measures the power supply voltage V0 of the analog signal output circuit and outputs it to the control unit 180. The control unit 180 uses the second control method to control the input range that can be handled by the differential stage 130 based on the power supply voltage V 0 of the analog signal output circuit measured by the monitor circuit 190.

  At this time, if the power supply voltage V0 is large, the control unit 180 performs control so that the input range that can be handled by the differential stage 130 is expanded. If the power supply voltage V0 is small, the control unit 180 reduces the input range that can be handled by the differential stage 130.

  Since the output voltage of an analog signal output circuit such as a sensor does not exceed its operating power supply voltage, the output voltage varies greatly by controlling the input range that can be handled by the differential stage 130 based on the power supply voltage V0. Even in the case of the second type of analog signal output circuit, appropriate processing of the analog signal SI by the analog front-end circuit 110 and reduction in power consumption of the differential stage 130 can be achieved.

  Further, since the fluctuation of the power supply voltage V0 is smaller than that of the analog signal SI, the compatible input range of the differential stage 130 is not changed during the A / D conversion of the analog signal SI. Operation can be ensured.

  A specific configuration example of the differential stage 130, a specific control method of the input range that can be handled by the analog front end circuit 110 by the control unit 180, and the like will be described in a later embodiment.

<Second Embodiment>
FIG. 2 shows a semiconductor device 200 according to the second embodiment. The semiconductor device 200 includes a first power generation circuit 210, a temperature sensor 212, a bridge sensor 214, a selector 216, a second power generation circuit 220, an analog front-end circuit 230, an MCU (Micro Computer Unit) 280, and a monitor circuit 290. The first power supply is supplied. Note that the voltage of the first power supply is V1, and is hereinafter referred to as “first power supply voltage”.

  The first power supply generation circuit 210 is supplied with the first power supply described above, and generates operating power for the temperature sensor 212 and the bridge sensor 214. The power supply voltage generated by the first power supply generation circuit 210 is V0.

  In this embodiment, as an example, the temperature sensor 212 and the bridge sensor 214 are supplied with the same power supply voltage V0 from the first power supply generation circuit 210, but the operating power supply of the temperature sensor 212 and the bridge sensor 214 is May be different.

Outputs from the temperature sensor 212 and the bridge sensor 214 are input to the selector 216.
The selector 216 selects one of the outputs from the temperature sensor 212 and the bridge sensor 214 as the analog signal SI and outputs the analog signal SI to the analog front end circuit 230.

  The second power generation circuit 220 is supplied with the first power described above, generates the second power, and supplies the second power to the second differential circuit 244, the output stage 150, and the ADC 160 described later of the analog front end circuit 230. To do. The voltage of the second power source generated by the second power source generation circuit 220 is the second power source voltage V2 lower than the first power source voltage V1.

  The analog front end circuit 230 includes a differential stage 240 to which an analog signal SI is input, a switch 252, a switch 254, an output stage 150, and an ADC 160. The differential stage 240, the switch 252, the switch 254, and the output stage 150 constitute an operational amplifier.

The differential stage 240 includes a first differential circuit 242 and a second differential circuit 244.
The first differential circuit 242 is composed of a high breakdown voltage transistor, and is applied with the first power supply voltage V1. The first differential circuit 242 is connected to the output stage 150 via the switch 252. When the switch 252 is “closed”, the output of the first differential circuit 242 is input to the output stage 150.

  The second differential circuit 244 is composed of a transistor having a lower breakdown voltage than the transistors constituting the first differential circuit 242, and a second power supply voltage V2 lower than the first power supply voltage V1 is applied to the second differential circuit 244. The second differential circuit 244 is connected to the output stage 150 via the switch 254. When the switch 254 is “closed”, the output of the second differential circuit 244 is input to the output stage 150.

  The switches 252 and 254 are controlled by the MCU 280 and are exclusively closed. That is, when one of the switches 252 and 254 is “closed”, the other is always “open”.

  The output stage 150 receives the second power supply voltage V2 as an operation power supply, amplifies the output of the first differential circuit 242 or the second differential circuit 244, and outputs the amplified output to the ADC 160. The ADC 160 receives the second power supply voltage V2 as an operation power supply, converts the signal from the output stage 150 into a digital signal, and outputs the digital signal to the MCU 280.

  FIG. 3 shows a specific circuit configuration example of the differential stage 240, the switch 252, the switch 254, and the output stage 150.

  As shown in the drawing, the first differential circuit 242 in the differential stage 240 is supplied with the first power supply as the operation power supply and is applied with the first power supply voltage V1. Each transistor included in the first differential circuit 242 is a high voltage transistor.

  The second differential circuit 244 in the differential stage 240 is characterized in that the second power supply is supplied as the operation power supply, the second power supply voltage V2 is applied, and that each transistor is a low breakdown voltage transistor. Except for the above, the first differential circuit 242 has the same configuration.

The switches 252 and 254 are transfer gates.
The output stage 150 is supplied with a second power supply as an operation power supply, and is applied with a second power supply voltage V2.

  FIG. 3 is merely an example, and the configuration of each circuit block is not limited. Of course, the N-type transistor and the P-type transistor in the drawing are also examples, and the conductivity type of the transistor is not limited.

Returning to FIG.
The monitor circuit 290 monitors the voltage of the analog signal SI and the power supply voltage V0, and outputs the monitoring result to the MCU 280.

  In addition to processing the output of the ADC 160, the MCU 280 has a function of a control unit that controls opening / closing of the switch 252 and the switch 254 based on the monitoring result by the monitor circuit 290.

  In the control, the MCU 280 can switch between a first control method based on the voltage of the analog signal SI and a second control method based on the power supply voltage V0. Specifically, the MCU 280 performs control by the first control method when the temperature sensor 212 is selected by the selector 216, and controls by the second control method when the bridge sensor 214 is selected by the selector 216. I do.

  Further, the input range that can be handled by the analog front end circuit 230 is generally required to be lower than the threshold voltage of the input PMOS of the differential circuit from the power supply voltage. Therefore, the input range increases as the power supply voltage increases, and the input range decreases as the power supply voltage decreases.

  When the switch 252 is “open” and the switch 254 is “closed”, the second differential circuit 244 does not operate and the first differential circuit 242 operates. The output of the first differential circuit 242 is input to the output stage 150. Since the first differential circuit 242 has an operating power supply of the first power supply and is applied with the first power supply voltage V1, in this case, the input range that the analog front end circuit 230 can handle is large.

  On the other hand, when the switch 252 is “closed” and the switch 254 is “open”, the switch 252 does not operate and the second differential circuit 244 operates. The output of the second differential circuit 244 is input to the output stage 150. In the second differential circuit 244, the operating power supply is the second power supply, and the second power supply voltage V2 lower than the first power supply voltage V1 is applied. In this case, the analog front end circuit 230 can cope with the second differential circuit 244. The input range is small.

  That is, in the present embodiment, the differential stage 240 of the analog front-end circuit 230 includes a first differential circuit 242 that operates with a first power source with a high voltage and a second differential circuit 240 that operates with a second power source with a low voltage. The differential circuit 244 includes two differential circuits 244, and the MCU 280 selectively operates the two differential circuits to control a corresponding input range of the analog front-end circuit 230.

  The semiconductor device 200 further embodies the semiconductor device 100 and can obtain all the effects of the semiconductor device 100.

<Third Embodiment>
FIG. 4 shows a semiconductor device 300 according to the third embodiment. The semiconductor device 300 is the same as the semiconductor device 200 except that an analog front end circuit 330 and an MCU 380 are provided instead of the analog front end circuit 230 and the MCU 280.

  The analog front end circuit 330 includes a differential circuit 340, a switch 352, a switch 354, an output stage 150, and an ADC 160.

  The switches 352 and 354 are controlled by the MCU 380 and are exclusively “closed”. That is, when one of the switches 352 and 354 is “closed”, the other is always “open”.

  In addition to processing the output of the ADC 160, the MCU 380 has a function of a control unit that controls opening / closing of the switch 352 and the switch 354 based on the monitoring result by the monitor circuit 290.

  In the control, the MCU 380 can switch between a first control method based on the voltage of the analog signal SI and a second control method based on the power supply voltage V0. Specifically, the MCU 380 performs control by the first control method when the temperature sensor 212 is selected by the selector 216, and controls by the second control method when the bridge sensor 214 is selected by the selector 216. I do.

  When the switch 352 is “closed” and the switch 354 is “open”, the differential circuit 340 has the operating power supply as the first power supply and is applied with the first power supply voltage V1. In this case, the input range that the analog front end circuit 330 can handle is large.

  On the other hand, when the switch 352 is “open” and the switch 354 is “closed”, the differential circuit 340 has a second power supply whose operating power supply is the second power supply, which is lower than the first power supply voltage V1. A power supply voltage V2 is applied. In this case, the input range that the analog front end circuit 330 can handle is small.

  That is, in the present embodiment, the differential stage of the analog front end circuit 330 is configured by only one differential circuit (differential circuit 340), and the MCU 380 supplies power to the differential circuit 340 with a voltage of The switchable input range of the analog front-end circuit 330 is controlled by switching between two different power sources.

  The semiconductor device 300 is a more realization of the semiconductor device 100, and all the effects of the semiconductor device 100 can be obtained in the same manner as the semiconductor device 200.

  In addition, since the differential stage in the analog front-end circuit 330 is configured by one differential circuit, the semiconductor device 300 has a smaller circuit scale than the semiconductor apparatus 200 in which the differential stage is configured by two differential circuits. .

<Fourth embodiment>
FIG. 5 shows a semiconductor device 400 according to the fourth embodiment. The semiconductor device 400 is the same as the semiconductor device 200 except that an MCU 480 and a monitor circuit 490 are provided instead of the MCU 280 and the monitor circuit 290.

  In addition to monitoring the voltage of the analog signal SI and the sensor operating power supply voltage V0, the monitor circuit 490 also monitors the first power supply voltage V1.

  The MCU 480 performs the same control as the MCU 280 in the semiconductor device 200 when the first power supply voltage V1 is larger than the predetermined threshold value and the first differential circuit 242 can be operated. That is, when the temperature sensor 212 is selected by the selector 216, the opening / closing of the switch 252 and the switch 254 is controlled based on the voltage of the analog signal SI monitored by the monitor circuit 490 by the first control method. Further, when the bridge sensor 214 is selected by the selector 216, the opening / closing of the switch 252 and the switch 254 is controlled based on the power supply voltage V0 monitored by the monitor circuit 490 by the second control method.

  On the other hand, when the first power supply voltage V1 falls below the predetermined threshold value and the first differential circuit 242 cannot be operated, the MCU 480 causes the monitor circuit 490 to output the analog signal SI and the power supply voltage. Regardless of the monitoring result of V0, the second differential circuit 244 is operated.

  This avoids the problem that the first differential circuit 242 cannot operate due to the decrease in the first power supply voltage V1 due to the instability of the first power supply, and consequently the analog front end circuit 230 cannot operate stably. It is to do.

  In particular, when the first power supply generation circuit 210 generates the operation power supply of the sensor from the first power supply as in the semiconductor device 200 and the semiconductor device 400, the power supply voltage V0 and the analog signal are reduced if the first power supply voltage V1 decreases. Since SI also decreases, there is no problem even if the input range that can be handled by the analog front end circuit 230 is reduced by selecting the second differential circuit 244.

<Fifth embodiment>
FIG. 6 shows a semiconductor device 500 according to the fifth embodiment. The semiconductor device 500 further includes a third power supply generation circuit 520 that supplies operation power to the first differential circuit 242. The monitor circuit 590 monitors the voltage of the analog signal SI, the power supply voltage V0, and the first power supply voltage V1. The MCU 580 controls the switch 252, the switch 254, and the third power supply generation circuit 520 based on the monitoring result. Except for these points, the semiconductor device 500 is the same as the semiconductor device 200.

  The third power supply generation circuit 520 includes a booster circuit 522, a switch 524, and a switch 526.

  The switches 524 and 526 are exclusively “closed” by the MCU 580. That is, when one of the switch 524 and the switch 526 is “closed”, the other is always “open”.

  Further, when the switch 526 is “open”, the booster circuit 522 is also controlled by the MCU 580 so as to stop the operation.

  That is, in the present embodiment, the operating power supply of the first differential circuit 242 is not the first power supply voltage V1 but a power supply generated by the third power supply generation circuit 520.

  The third power supply generation circuit 520 supplies the first power supply voltage V1 to the first differential circuit 242 as it is when the switch 524 is “closed” and the switch 526 is “open”.

  On the other hand, when the switch 524 is “open” and the switch 526 is “closed”, the third power supply generation circuit 520 boosts the first power supply voltage V1 and supplies it to the first differential circuit 242. To do.

  Note that immediately after the semiconductor device 500 is turned on, the third power generation circuit 520 supplies the first power source voltage V1 as it is to the first differential circuit 242 as an operating power source.

  When the MCU 580 performs control using the first control method or the second control method and determines that the first differential circuit 242 should be operated, the MCU 580 further uses the first power supply voltage V1 as it is. It is determined whether the supply to the dynamic circuit 242 is maintained or the first power supply voltage V1 is boosted and supplied to the first differential circuit 242, and the third power supply generation circuit 520 is set according to the determination result. Control.

  Specifically, when the first power supply voltage V1 is larger than a predetermined threshold value and the first differential circuit 242 can be operated, the MCU 580 uses the first power supply voltage V1 as it is as the first difference. The supply to the dynamic circuit 242 is maintained.

  On the other hand, when the first power supply voltage V1 falls below the predetermined threshold value and the first differential circuit 242 cannot be operated, the MCU 580 boosts the first power supply voltage V1. The third power generation circuit 520 is controlled so as to be supplied to the first differential circuit 242.

  As in the case of the semiconductor device 400, this is because the first differential circuit 242 cannot operate due to a decrease in the first power supply voltage V1 due to the instability of the first power supply, and consequently the analog front end circuit 230. This is to avoid the problem that stable operation is not possible.

<Sixth Embodiment>
FIG. 7 shows a semiconductor device 600 according to the sixth embodiment. The semiconductor device 600 includes a first power generation circuit 210, a temperature sensor 212, a bridge sensor 214, a second power generation circuit 220, an analog front end circuit 630, an MCU 680, and a monitor circuit 290.

  The analog front end circuit 630 includes a selector 610, a differential stage 240, a switch 252, a switch 254, an output stage 150, an ADC 160, and a control unit 640.

  The selector 610 includes a switch SW1 to which the output of the temperature sensor 212 is input and a switch SW2 to which the output of the bridge sensor 214 is input. The two switches are exclusively “closed”.

  That is, when the switch SW1 is selected, the output of the temperature sensor 212 is input to the analog front end circuit 630 as the analog signal SI, and when the switch SW2 is selected, the output of the bridge sensor 214 is analog as the analog signal SI. Input to the front-end circuit 630.

  The control unit 640 is controlled by a control unit 682 described later of the MCU 680. Specifically, opening / closing of the switch 252 and the switch 254 is controlled according to the setting information received from the control unit 682.

  The MCU 680 includes a control unit 682, a register 684, and a register 686. The register 684 and the register 686 are for storing setting information corresponding to the switch SW1 and the switch SW2 in the selector 610, respectively. The setting information is written in each register by the control unit 682.

  First, a case where the semiconductor device 600 is turned on for the first time and no information is stored in the registers 684 and 686 will be described.

  In this case, the control unit 682 generates setting information for controlling the switch 252 and the switch 254 based on the switch selected by the selector 610 and the monitoring result of the monitor circuit 290. The control unit 682 outputs the generated setting information to the control unit 640 and writes it in a register corresponding to the selected switch in the selector 610.

  For example, when the switch SW1 corresponding to the temperature sensor 212 is selected, the control unit 682 determines that the control should be performed by the first control method, and sets the voltage of the analog signal SI monitored by the monitor circuit 290. Based on this, setting information indicating opening / closing of the switch 252 and the switch 254 is generated. As an example, it is assumed that setting information indicating that the switch 252 is “open” and the switch 254 is “closed” is generated. The control unit 682 outputs the generated setting information to the control unit 640 and writes it in the register 684.

  The control unit 640 sets the switch 252 to “open” and the switch 254 to “close” in accordance with the setting information from the control unit 682.

  Similarly, when the bridge sensor 214 is selected, the control unit 682 determines that the control should be performed by the second control method, and switches 252 based on the power supply voltage V0 monitored by the monitor circuit 290. And setting information indicating opening / closing of the switch 254 is generated. As an example, it is assumed that setting information indicating that the switch 252 is “closed” and the switch 254 is “open” is generated. The control unit 682 outputs the generated setting information to the control unit 640 and writes it in the register 684.

  The control unit 640 sets the switch 252 to “closed” and the switch 254 to “open” in accordance with the setting information from the control unit 682.

  Thus, setting information corresponding to the corresponding switch in the selector 610 is accumulated in the register 684 and the register 686 as the semiconductor device 600 is used.

  When the setting information is accumulated in the register 684 and the register 686, the control unit 682 obtains the setting information from the register corresponding to the switch after the switch every time the switch in the selector 610 is switched, that is, the sensor is switched. Read out and output to the control unit 640.

  With such a configuration, when the sensor that outputs the measurement result (analog signal SI) is switched to the analog front end circuit 630, the semiconductor device 600 reads the setting information from the corresponding register and outputs the setting information to the control unit 640. Then, since the control unit 640 performs the control defined by the setting information, it is possible to reduce the time and the amount of calculation required for processing the monitor result by the monitor circuit 290.

  As mentioned above, the invention made by the present inventor has been specifically described based on the embodiments. However, the present invention is not limited to the embodiments already described, and various modifications can be made without departing from the scope of the invention. It goes without saying that it is possible.

  For example, the semiconductor device 600 shown in FIG. 7 stores each setting for realizing the control to be performed at the time of selection by a register corresponding to each selection by the selector 610. Accordingly, the control according to each setting stored in the register corresponding to the selection is applied to the semiconductor device 200 shown in FIG. Such a thing may be applied to the semiconductor device 300 shown in FIG.

  Further, for example, a simulation of the analog front-end circuit 630 illustrated in FIG. 7 may be performed in advance by a simulator, and each setting information obtained from the simulation result may be written in the register 684 and the register 686. In this way, the semiconductor device 600 can be controlled with reference to the register from the first power-on.

DESCRIPTION OF SYMBOLS 100 Semiconductor device 110 Analog front end circuit 120 Operational amplifier 130 Differential stage 150 Output stage 160 AD converter (ADC)
180 control unit 190 monitor circuit 200 semiconductor device 210 first power generation circuit 212 temperature sensor 214 bridge sensor 216 selector 220 second power generation circuit 230 analog front end circuit 240 differential stage 242 first differential circuit 244 second Differential circuit 252, 254 switch 280 MCU (MicroComputer Unit)
290 Monitor circuit 300 Semiconductor device 330 Analog front end circuit 340 Differential circuit 352, 354 Switch 380 MCU (MicroComputer Unit)
400 Semiconductor device 480 MCU (MicroComputer Unit)
490 Monitor circuit 500 Semiconductor device 510 First power generation circuit 520 Third power generation circuit 522 Boost circuit 524, 526 Switch 580 MCU (MicroComputer Unit)
590 Monitor circuit 600 Semiconductor device 610 Selector 630 Analog front end circuit 640 Control unit 680 MCU
682 Control unit 684 Register 686 Register SI Analog signal SW1, SW2 Switch V0 Sensor power supply voltage V1 First power supply voltage V2 Second power supply voltage

Claims (10)

A differential stage to which an analog signal is input;
A control unit for controlling the voltage range of the analog signal that can be supported by the differential stage with respect to the differential stage;
The controller is
When controlling the differential stage, a first control system based on the voltage of the analog signal and a second control system based on an operating power supply voltage of an analog signal output circuit that outputs the analog signal to the differential stage And can be switched,
Semiconductor device. The differential stage is an input stage of an analog front end circuit for converting an analog signal into a digital signal.
The semiconductor device according to claim 1. The controller is
Switching between the first control method and the second control method according to the type of the analog signal output circuit,
The semiconductor device according to claim 1. The analog signal output circuit is classified according to the magnitude of the voltage fluctuation of the analog signal to be output.
The semiconductor device according to claim 3. The differential stage is:
A first differential circuit to which a first power supply is supplied;
A second differential circuit to which a second power source having a voltage lower than that of the first power source is supplied,
The controller is
Controlling the differential stage by selectively operating the first differential circuit and the second differential circuit;
The semiconductor device according to claim 1. The control unit does not perform control based on the voltage of the analog signal and the operating power supply voltage of the analog signal output circuit when the voltage of the first power supply becomes a predetermined threshold value or less. 2 differential circuits are operated,
The semiconductor device according to claim 5. The first power supply is further provided as an operation power supply, and further includes a first power supply generation circuit that generates an operation power supply for the analog signal output circuit.
The semiconductor device according to claim 6. A third power generation circuit that supplies the first power source as it is to the first differential circuit as an operating power source or boosts the first power source to supply the first differential circuit as an operating power source. In addition,
The control unit further includes:
In the case of operating the first differential circuit, when the voltage of the first power supply becomes equal to or lower than a predetermined threshold, the first power supply is boosted to the first differential circuit. Controlling the third power generation circuit to supply,
The semiconductor device according to claim 5. The differential stage is composed of one differential circuit,
The control unit controls the differential stage by selectively supplying a first power source and a second power source having a lower voltage than the first power source as an operation power source to the differential circuit.
The semiconductor device according to claim 1. A selector that selects one of outputs from a plurality of analog signal output circuits as the analog signal and inputs the analog signal to the differential stage;
A plurality of storage units each corresponding to each selection by the selector, further comprising the plurality of storage units for storing each setting for realizing the control performed by the control unit at the time of the selection;
The control unit performs control according to each setting stored in the storage unit corresponding to the selection according to the selection of the selector.
The semiconductor device according to claim 1.

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