JP2017212643A - A/d conversion circuit, coulomb counter circuit, and electronic apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve reliability and an A/D converter.SOLUTION: A first multiplexer 104 receives an analog signal Vand a diagnosis voltage V, selects one of them, and outputs the selected one. An A/D converter 106 converts an output signal S1 of the first multiplexer 104 to a digital signal S2. A memory 108 stores diagnosis data S4 corresponding to an expectation value of the digital signal S2 at a time of inputting the diagnosis voltage Vinto the normal A/D converter 106. A logic circuit 110 allows the first multiplexer 104 to select the analog signal Vat a normal operation, and processes the digital signal S2 obtained at the time. The logic circuit 110 allows the first multiplexer 104 to select the diagnosis voltage Vat the time of a self diagnosis, and detests an abnormal state of the A/D converter 106 on the basis of a relationship of the digital signal S2 and the diagnosis data S4 obtained at the time.SELECTED DRAWING: Figure 1

Description

  The present invention relates to A / D conversion.

  In various electronic devices, an A / D converter that converts an analog signal representing these states into a digital signal is used to detect an electrical state of an internal circuit and a physical state of the electronic device and perform digital signal processing. .

JP 2014-014029 A JP, 2015-102318, A

  As a result of examining the A / D converter, the present inventors have recognized the following problems.

  If the A / D converter fails completely and becomes inoperable, the digital signal has no correlation with the analog signal. In this case, it is possible to recognize an abnormality in a subsequent processor or circuit that uses the output signal of the A / D converter.

  However, the A / D converter may have an incomplete failure due to deterioration over time. An incomplete failure is a failure mode in which some abnormality has occurred, but the A / D converter operates at first glance, and some output signal is generated although it is inaccurate. When an incomplete failure occurs, the subsequent processor or circuit operates based on an erroneous output signal, which causes a malfunction of the system.

  The present inventor has been made in view of such a problem, and one of exemplary purposes of an aspect thereof is to provide an A / D converter with improved reliability.

  One embodiment of the present invention relates to an A / D conversion circuit. The A / D conversion circuit receives a reference voltage source that generates a predetermined diagnostic voltage, a first multiplexer (selector) that receives an analog signal and a diagnostic voltage, and selects and outputs one, and an output signal of the first multiplexer An A / D converter that converts a digital signal into a digital signal, a memory that stores diagnostic data corresponding to an expected value of the digital signal when a diagnostic voltage is input to a normal A / D converter, and (i) during normal operation The first multiplexer selects an analog signal and processes the digital signal obtained at that time, and (ii) causes the first multiplexer to select a diagnostic voltage at the time of self-diagnosis, and the digital signal and diagnostic data obtained at that time And a logic circuit for detecting an abnormality of the A / D converter based on the above relationship.

  According to this aspect, when the A / D conversion circuit performs self-diagnosis, not only a failure that makes the A / D converter inoperable but also an incomplete failure can be detected, and reliability can be improved.

  The logic circuit may detect an abnormality of the A / D converter based on a comparison result between the digital signal and a threshold value based on the diagnostic data. In this case, the abnormality of the A / D converter can be determined by a simple process of size comparison.

  The diagnostic data may include an upper threshold, and the logic circuit may determine that an abnormality has occurred when the digital signal exceeds the upper threshold. The diagnostic data may include a lower threshold value, and the logic circuit may determine that an abnormality has occurred when the digital signal falls below the lower threshold value.

  The A / D converter may be a ΔΣ A / D converter.

  The input reference value of the A / D converter may be switched during normal operation and self-diagnosis.

  The A / D conversion circuit may be further provided with an amplifier that is provided before the first multiplexer and amplifies the analog signal.

  The first multiplexer may receive a plurality of analog signals and select one from the plurality of analog signals and the diagnostic voltage.

  The logic circuit may change the threshold according to the temperature of the A / D conversion circuit. As a result, it is possible to perform abnormality determination in consideration of the effect of temperature drift.

  The A / D conversion circuit may be integrated on a single semiconductor substrate. “Integrated integration” includes the case where all of the circuit components are formed on a semiconductor substrate and the case where the main components of the circuit are integrated. A resistor, a capacitor, or the like may be provided outside the semiconductor substrate. By integrating the circuit on one chip, the circuit area can be reduced and the characteristics of the circuit elements can be kept uniform.

  Another aspect of the present invention relates to a coulomb counter circuit for calculating a charge / discharge charge amount of a battery. The coulomb counter circuit is a differential input port, and an amplifier that amplifies a potential difference between the differential input port to which a detection voltage indicating a battery current is input and a differential input port between them as a reference A reference voltage source that generates a predetermined diagnostic voltage, a first multiplexer that receives and outputs an amplifier output signal and a diagnostic voltage, and a second multiplexer that receives a predetermined voltage and a ground voltage and selects one And an A / D converter that converts the output signal of the first multiplexer into a digital signal, and a memory that stores diagnostic data corresponding to an expected value of the digital signal when a diagnostic voltage is input to a normal A / D converter (I) In normal operation, the first multiplexer selects the output signal of the amplifier, and the second multiplexer selects the predetermined voltage. (Ii) causes the first multiplexer to select a diagnostic voltage and causes the second multiplexer to select a ground voltage during self-diagnosis, and based on the relationship between the digital signal and the diagnostic data obtained at that time And a logic circuit for detecting an abnormality of the A / D converter, and an interface circuit for outputting diagnostic data indicating an integrated value of the battery current generated by the logic circuit to the outside.

  The coulomb counter circuit may further include a single-ended input port that receives an analog signal. The first multiplexer may receive one of the amplifier output signal, the input port signal, and the diagnostic voltage to select one.

  The logic circuit may change the threshold value according to the temperature of the coulomb counter circuit.

  The coulomb counter circuit may be integrated on a single semiconductor substrate.

  Another embodiment of the present invention relates to an electronic device. The electronic device includes a battery, a charging circuit that charges the battery, a load of the battery, a coulomb counter circuit that detects charge / discharge charges of the battery, and a remaining battery level detection circuit based on the output of the coulomb counter circuit. And a quantity detection circuit.

  Note that any combination of the above-described constituent elements and the constituent elements and expressions of the present invention replaced with each other among methods, apparatuses, systems, and the like are also effective as an aspect of the present invention.

  According to the present invention, the reliability of the A / D converter can be improved.

It is a block diagram of the A / D conversion circuit concerning an embodiment. It is a flowchart which shows operation | movement of an A / D conversion circuit. 3A and 3B are diagrams for explaining the state of the A / D conversion circuit in the comparison process of the flowchart of FIG. It is a circuit diagram which shows the structural example of an A / D conversion circuit. It is a block diagram of an electronic device provided with the coulomb counter circuit which concerns on embodiment.

  The present invention will be described below based on preferred embodiments with reference to the drawings. The same or equivalent components, members, and processes shown in the drawings are denoted by the same reference numerals, and repeated descriptions are omitted as appropriate. The embodiments do not limit the invention but are exemplifications, and all features and combinations thereof described in the embodiments are not necessarily essential to the invention.

  In this specification, “the state in which the member A is connected to the member B” means that the member A and the member B are physically directly connected, or the member A and the member B are electrically connected to each other. Including the case of being indirectly connected through other members that do not substantially affect the state of connection, or do not impair the functions and effects achieved by the combination thereof.

  Similarly, “the state in which the member C is provided between the member A and the member B” refers to the case where the member A and the member C or the member B and the member C are directly connected, as well as their electric It includes cases where the connection is indirectly made through other members that do not substantially affect the general connection state, or that do not impair the functions and effects achieved by their combination.

FIG. 1 is a block diagram of an A / D conversion circuit 100 according to the embodiment. The A / D conversion circuit 100 includes a reference voltage source 102, a first multiplexer 104, an A / D converter 106, and a memory 108. The A / D conversion circuit 100 converts the analog input voltage V _ANLG into a digital signal D _OUT and performs predetermined signal processing during normal operation. Further, the A / D conversion circuit 100 has a function of self-diagnosis of an abnormality or failure of the A / D converter 106.

The reference voltage source 102 generates a predetermined diagnostic voltage V _DIAG . The diagnostic voltage V _DIAG is defined near the center of the input range of the A / D converter 106, but is not limited thereto.

The first multiplexer 104 receives the analog signal V _ANLG and the diagnostic voltage V _DIAG , and selects and outputs one of them according to the selection signal S6 from the logic circuit 110. The A / D converter 106 converts the output signal S1 of the first multiplexer 104 into a digital signal S2.

The memory 108 stores diagnostic data S4 corresponding to the expected value S3 of the digital signal S2 when the diagnostic voltage V _DIAG is input to the normal A / D converter 106. For example, in the inspection process before shipment of the A / D conversion circuit 100, the diagnosis voltage V _DIAG may be selected by the first multiplexer 104, and the digital signal S2 from the A / D converter 106 at that time may be set as the expected value S3. . Alternatively, a design value may be used as the expected value S3.

  The memory 108 may be a non-volatile memory. In this case, the diagnostic data S4 corresponding to the expected value S3 is written to the memory 108 before the A / D conversion circuit 100 is shipped. The diagnosis data S4 may be a threshold value S5 determined from the expected value S3.

The logic circuit 110 (i) _causes the first multiplexer 104 to select the analog signal V _ANLG during normal operation, and processes the digital signal S2 obtained at that time. This is referred to as normal processing, and the logic circuit 110 has a circuit block (or function) 112 for normal processing.

Further, the logic circuit 110 (ii) causes the first multiplexer 104 to select the diagnostic voltage V _DIAG at the time of self-diagnosis, and based on the relationship between the digital signal S2 obtained at that time and the diagnostic data S4 stored in the memory 108, An abnormality in the A / D converter 106 is detected. The logic circuit 110 has a circuit block (or function) 114 for self-diagnosis.

  The diagnostic data S4 stored in the memory 108 includes an upper threshold value S5U, and the logic circuit 110 determines that an abnormality has occurred when the digital signal S2 exceeds the upper threshold value S5U. Further, the diagnostic data S4 includes a lower threshold value S5L, and the logic circuit 110 determines that an abnormality has occurred when the digital signal S2 falls below the lower threshold value S5L. The circuit block 114 may include a digital comparator.

  The above is the configuration of the A / D conversion circuit 100. Next, the operation will be described. FIG. 2 is a flowchart showing the operation of the A / D conversion circuit 100. When the A / D conversion circuit 100 is activated, an initialization sequence S100 is executed, and then the process proceeds to a self-diagnosis sequence S200. Self-diagnosis sequence S200 includes processes S202 to S214.

The reference voltage source 102 generates the diagnostic voltage V _DIAG (S202), and the first multiplexer 104 selects the diagnostic voltage V _DIAG and inputs it to the A / D converter 106 (S204). The A / D converter 106 converts the diagnostic voltage V _DIAG into a digital signal S2 (S206).

  The logic circuit 110 reads the diagnostic data S4 from the memory 108 and acquires threshold values S5U and S5L (S208). The digital signal S2 is compared with threshold values S5U and S5L (S210). When S5L <S2 <S5U (Y in S210), the A / D converter 106 is determined to be normal (S212), and the process proceeds to normal operation S102. When S5L> S2 or S2> S5U (N in S210), the A / D converter 106 is determined to be abnormal (S214), and error processing S104 is executed as necessary.

  Note that the flowchart of FIG. 2 and the order of the processes are not limited, and the order of the processes may be changed as long as the process does not fail.

  FIGS. 3A and 3B are diagrams illustrating the state of the A / D conversion circuit 100 in the comparison process S210 of the flowchart of FIG. As described above, the logic circuit 110 includes the digital comparator COMP. As shown in FIG. 3A, the digital signal S2 is input to the non-inverting input of the digital comparator COMP, and the upper threshold value S5U is input to the inverting input. At this time, if S2> S5U, the abnormality determination signal S8 is asserted (high level). As shown in FIG. 3B, the lower threshold value S5L is input to the non-inverting input of the digital comparator COMP, and the digital signal S2 is input to the inverting input. At this time, if S2 <S5L, the abnormality determination signal S8 is asserted (high level). Two digital comparators COMP may be provided, and the comparison processing of FIGS. 3A and 3B may be executed simultaneously.

  The above is the operation of the A / D conversion circuit 100. According to the A / D conversion circuit 100, by executing self-diagnosis, not only a failure that causes the A / D converter 106 to be completely inoperable but also an incomplete failure can be detected, thereby improving reliability. it can.

  The present invention is understood as the block diagram and circuit diagram of FIG. 1 or the flowchart of FIG. 2 or extends to various devices, circuits and methods derived from the above description, and is limited to a specific configuration. is not. In the following, more specific configuration examples and examples will be described in order not to narrow the scope of the present invention but to help understanding and clarify the essence and circuit operation of the present invention.

  FIG. 4 is a circuit diagram showing a configuration example (100a) of the A / D conversion circuit 100. The A / D conversion circuit 100a is an A / D converter IC that includes a second multiplexer 116, an amplifier 120, and an interface circuit 122 in addition to the A / D conversion circuit 100 of FIG. 1, and is integrated on one semiconductor substrate. is there.

The differential input ports INP and INN are paired, and the potential difference _VIN between them is an analog input. Amplifier 120 is provided before the first multiplexer 104, and amplifies the potential difference _{V IN,} and generates an analog voltage _{V ANLG1.} The amplifier 120 may be a summing amplifier and may output V _ANLG1 = α × V _IN + β × V _REF . V _REF defines an offset amount. The gain of the amplifier 120 may be variable.

Further, the A / D conversion circuit 100a includes analog ports PORT1 and PORT2, to which analog voltages V _ANLG2 and V _ANLG3 can be input. The first multiplexer 104 receives the analog voltages V _{ANLG1 to} V _ANLG3 and the diagnostic voltage V _DIAG and selects one corresponding to the selection signal S6. Specifically, the diagnostic voltage V _DIAG is selected during self-diagnosis, and a plurality of analog voltages V _{ANLG1 to} V _ANLG3 are selected in a time division manner during normal operation.

The A / D converter 106 is a ΔΣ A / D converter. As described above, during normal operation, the amplifier 120 offsets (shifts) the input voltage _VIN based on the reference voltage _VREF . Corresponding to this offset, a reference voltage V _REF is applied as an input reference value Va of the A / D converter 106 during normal operation. The A / D converter 106 has a differential input, and the input reference value Va may be a voltage supplied to the inverting input terminal of the A / D converter 106. Thereby, the potential difference _VIN between the differential input ports INP and INN can be converted into a digital value S2 without the influence of the reference voltage _VREF in the amplifier 120.

On the other hand, at the time of self-diagnosis, the input reference value Va of the A / D converter 106 may be zero. Therefore, the second multiplexer 116 receives the reference voltage V _REF and the ground voltage V _GND , selects one according to the selection signal S 7 from the logic circuit 110, and supplies it to the A / D converter 106.

  The interface circuit 122 outputs data obtained by signal processing of the logic circuit 110 during normal operation to an external microcomputer or processor connected to the OUT pin. Alternatively, when an abnormality of the A / D converter 106 is detected in the self-diagnosis sequence, the abnormality may be notified.

  The above is the configuration of the A / D conversion circuit 100a. Next, the application of the A / D conversion circuit 100a will be described. The A / D conversion circuit 100a can be used as a general-purpose A / D converter IC, but by adding various functions to the logic circuit 110, an IC for a specific application can be configured. As described above, since the A / D conversion circuit 100a has a self-diagnosis function, it is suitable for applications that require high reliability over a long period of time.

  FIG. 5 is a block diagram of an electronic device 300 including the coulomb counter circuit 200 according to the embodiment. The coulomb counter circuit 200 is configured based on the A / D conversion circuit 100a of FIG. The coulomb counter circuit 200 is mounted on the electronic device 300.

  In addition to the coulomb counter circuit 200, the electronic device 300 includes a battery 302, a current sensor 304, a microcomputer 306, a charging circuit 308, and a load 310. The battery 302 is a rechargeable secondary battery such as a lithium ion battery or a nickel metal hydride battery.

  The charging circuit 308 receives power supply from the outside and charges the battery 302. The load 310 operates by receiving power supply from the battery 302.

  The ground pins (GND, DGND) of the coulomb counter circuit 200 are grounded. The power supply pin (VCC) is supplied with the power supply voltage of the analog block, and the power supply pin (VDD) is supplied with the power supply voltage of the digital block.

The current sensor 304 measures the charge / discharge current I _BAT flowing through the battery 302. The current sensor 304 can be configured by, for example, a sense resistor R _S provided in series with the battery 302, and the voltage drop V _S of the sense resistor R _S is used as the analog voltage V _IN indicating the amount of current. Are input to the differential input ports INP and INN. The current sensor 304 may be a current sense amplifier.

The reference voltage source 202 and the internal voltage source 204 generate reference voltages V _REF25 and V _REF15 having different voltage levels. The reference voltage (VREF25) terminal and the internal voltage (VREF15) terminal are connected to the outputs of the reference voltage source 202 and the internal voltage source 204, respectively, and an external smoothing capacitor is connected. Further, the reference voltage V _REF25 and the internal voltage V _REF15 can be referred to from an external circuit of the coulomb counter circuit 200. Note that the reference voltage source 102 may be shared with the reference voltage source 202 or the internal voltage source 204.

Amplifier 120 is a differential amplifier noninverting, input analog signal _{V S,} the reference voltage _{V REF25} amplified as a reference, to produce an analog voltage _{V ANLG1.} The A / D converter 106 converts the analog signal V _ANLG selected by the first multiplexer 104 into a digital signal S2 using the reference voltages V _REF25 and V _REF15 . A digital signal _S 2 corresponding to the detection signal V _S indicates the charge / discharge current I _BAT of the battery 302.

  The coulomb counter circuit 200 is used to detect the remaining amount of the battery by the coulomb count method, and is an integrated value of the charge amount of the battery (CCC: Charge Coulomb Count) and an integrated value of the discharge amount of the battery (DCC: Discharge Coulomb Count). At least one of the accumulated count values (ACC: Accumulate Coulomb Count) is generated.

The oscillator 206 generates an internal clock. The logic circuit 110 operates in synchronization with the internal clock. The logic circuit 110 includes an integrator 130, a data register 132, and the like. These correspond to the circuit block 112 of FIGS. The integrator 130 may integrate the digital signal S2 corresponding to the positive current I _BAT to generate a CCC value. Further, the integrator 130 may integrate the digital signal S2 corresponding to the negative current I _BAT to generate a DCC value. Further, the integrator 130 may integrate the digital signal S2 regardless of whether it is positive or negative to generate an ACC value.

  The coulomb count value generated by the integrator 130 is written in the data register 132. The value of the data register 132 can be accessed from the microcomputer 306 via the interface circuit 122. The interface circuit 122 is, for example, an SPI (Serial Peripheral Interface). SDI is a data input terminal, SDO is a data output terminal, CS is a chip select terminal, and CLK is a serial clock input terminal.

  The microcomputer 306 calculates the remaining amount of the battery 302 based on the coulomb count value. The microcomputer 306 is also referred to as a fuel gauge IC (remaining amount detection circuit).

  Further, the logic circuit 110 includes a self-diagnosis circuit 134 and an alarm output circuit 136. These correspond to the circuit block 114 of FIG. 1 and FIG. The self-diagnosis circuit 134 performs comparison processing at the time of self-diagnosis, and determines whether the A / D converter 106 is abnormal. The alarm output circuit 136 asserts an ALARM pin signal and notifies the microcomputer 306 when an abnormality of the A / D converter 106 or other abnormality is detected.

  The coulomb counter circuit 200 further includes an interrupt output pin INT. An external microcomputer 306 is connected to the INT pin. When a predetermined interrupt event occurs inside the coulomb counter circuit 200, the logic circuit 110 interrupts the microcomputer 306 via the INT pin. Examples of the interrupt event include completion of calibration.

  The present invention has been described based on the embodiments. This embodiment is an exemplification, and it will be understood by those skilled in the art that various modifications can be made to combinations of the respective constituent elements and processing processes, and such modifications are within the scope of the present invention. is there. Hereinafter, such modifications will be described.

(First modification)
In the embodiment, the diagnosis data S4 stored in the memory 108 is the threshold value S5. However, the present invention is not limited to this. For example, the diagnostic data S4 may be the expected value S3. The logic circuit 110 may generate the threshold value S5 by adding or subtracting a margin to the expected value S3.

In the embodiment, the upper threshold value and the lower threshold value are provided. However, the diagnostic voltage V _DIAG may be set near the maximum value of the full scale, and only the lower threshold value may be defined. Conversely, the diagnostic voltage V _DIAG may be set in the vicinity of the minimum value of the full scale and only the upper threshold value may be defined.

(Second modification)
In the embodiment, at the time of self-diagnosis, the logic circuit 110 compares the diagnosis data S4 with the expected value S3 to determine whether the A / D converter 106 is abnormal. However, the present invention is not limited to this. The logic circuit 110 may diagnose the A / D converter 106 based on a value obtained as a result of performing predetermined arithmetic processing on the diagnosis data S4. For example, the logic circuit 110 may measure the digital signal S2 corresponding to the diagnostic voltage V _{DIAG a} plurality of times, and compare an average value of the plurality of measured values with a threshold value.

(Third Modification)
The A / D conversion circuit 100 may change the diagnostic voltage V _DIAG by a binary value or a ternary value or more. The diagnostic data S4 in the memory 108 is prepared for each value of the diagnostic voltage V _DIAG , and the logic circuit 110 determines _whether the A / D converter 106 is normal or abnormal for each value of the diagnostic voltage V _DIAG. Good. In this case, accuracy can be increased.

(Fourth modification)
The A / D converter 106 may have temperature dependency. In this case, the logic circuit 110 may change the threshold value S5 according to the temperature. When the temperature dependency of the A / D converter 106 is large and the threshold value S5 is constant, it is necessary to consider a large margin when defining the threshold value S5. On the other hand, when the temperature dependence is given to the threshold value S5, the margin can be reduced, so that more accurate diagnosis is possible.

(5th modification)
The memory 108 may be a volatile memory such as a register, SRAM, or DRAM. In this case, a non-volatile memory is provided on the host processor connected to the A / D conversion circuit 100, and the diagnostic data S4 is stored in the memory 108 of the A / D conversion circuit 100 each time the A / D conversion circuit 100 is activated. You may make it write in.

(Sixth Modification)
The coulomb counter circuit 200 shown in FIG. 5 can be used not only for electronic equipment but also for household or plant power storage systems, electric cars, hybrid cars, and plug-in hybrid cars.

(Seventh Modification)
The type of the A / D converter 106 is not particularly limited, and may be a SAR (successive comparison type) A / D converter, other A / D converters, in addition to the ΔΣ A / D converter.

(Eighth modification)
The self-diagnosis may be performed at an appropriate timing or cycle, and is not necessarily performed when the A / D conversion circuit 100 is activated.

  Although the present invention has been described using specific terms based on the embodiments, the embodiments only illustrate the principles and applications of the present invention, and the embodiments are defined in the claims. Many variations and modifications of the arrangement are permitted without departing from the spirit of the present invention.

DESCRIPTION OF SYMBOLS 100 ... A / D conversion circuit, 102 ... Reference voltage source, 104 ... 1st multiplexer, 106 ... A / D converter, 108 ... Memory, 110 ... Logic circuit, 112, 114 ... Circuit block, 116 ... 2nd multiplexer, 120 ... Amplifier 122 ... Interface circuit 200 ... Coulomb counter circuit 202 ... 300 300 Electronic equipment 302 ... Battery 304 ... Current sensor 306 ... Microcomputer 308 ... Charging circuit 310 ... Load S2 ... Digital signal S3 ... expected value, S4 ... diagnostic data, S5 ... threshold value.

Claims (19)

A reference voltage source for generating a predetermined diagnostic voltage;
A first multiplexer for receiving an analog signal and the diagnostic voltage, and selecting and outputting one of them;
An A / D converter for converting an output signal of the first multiplexer into a digital signal;
A memory for storing diagnostic data corresponding to an expected value of the digital signal when the diagnostic voltage is input to the normal A / D converter;
(I) Let the first multiplexer select the analog signal during normal operation, process the digital signal obtained at that time, and (ii) select the diagnostic voltage for the first multiplexer during self-diagnosis A logic circuit for detecting an abnormality of the A / D converter based on the relationship between the digital signal and the diagnostic data obtained at that time;
An A / D conversion circuit comprising:   2. The A / D conversion according to claim 1, wherein the logic circuit detects an abnormality of the A / D converter based on a comparison result between the digital signal and a threshold value based on the diagnostic data. circuit.   3. The A according to claim 1, wherein the diagnostic data includes an upper threshold value, and the logic circuit determines that an abnormality occurs when the digital signal exceeds the upper threshold value. / D conversion circuit.   The diagnostic data includes a lower threshold value, and the logic circuit determines that an abnormality occurs when the digital signal falls below the lower threshold value. An A / D conversion circuit according to claim 1.   The A / D converter circuit according to claim 1, wherein the A / D converter is a ΔΣ A / D converter.   6. The A / D converter circuit according to claim 1, wherein an input reference value of the A / D converter is switched during the normal operation and the self-diagnosis.   The A / D conversion circuit according to claim 1, further comprising an amplifier that is provided in a preceding stage of the first multiplexer and amplifies the analog signal.   The A / D conversion circuit according to claim 1, wherein the first multiplexer receives a plurality of analog signals and selects one of the plurality of analog signals and the diagnostic voltage.   The A / D conversion circuit according to claim 1, wherein the logic circuit changes the threshold value according to a temperature of the A / D conversion circuit.   10. The A / D conversion circuit according to claim 1, wherein the A / D conversion circuit is integrated on a single semiconductor substrate. A coulomb counter circuit for calculating a charge / discharge charge amount of a battery,
A differential input port between which a detection voltage indicating the current of the battery is input;
An amplifier that amplifies the potential difference of the differential input port with reference to a predetermined voltage;
A reference voltage source for generating a predetermined diagnostic voltage;
A first multiplexer receiving the output signal of the amplifier and the diagnostic voltage and selecting one;
A second multiplexer that receives the predetermined voltage and the ground voltage and selects one;
An A / D converter for converting an output signal of the first multiplexer into a digital signal;
A memory for storing diagnostic data corresponding to an expected value of the digital signal when the diagnostic voltage is input to the normal A / D converter;
(I) causing the first multiplexer to select the output signal of the amplifier during normal operation, causing the second multiplexer to select the predetermined voltage, and integrating the digital signal obtained at that time, and (ii) self At the time of diagnosis, the first multiplexer is made to select the diagnostic voltage, the second multiplexer is made to select the ground voltage, and the A / D converter is based on the relationship between the digital signal and the diagnostic data obtained at that time. A logic circuit for detecting an abnormality in the
An interface circuit for outputting data indicating an integrated value of the battery current generated by the logic circuit to the outside;
A coulomb counter circuit comprising:   12. The coulomb counter circuit according to claim 11, wherein the logic circuit detects an abnormality of the A / D converter based on a comparison result between the digital signal and a threshold value based on the diagnostic data.   13. The coulomb according to claim 11 or 12, wherein the diagnostic data includes an upper threshold value, and the logic circuit determines that an abnormality occurs when the digital signal exceeds the upper threshold value. Counter circuit.   14. The diagnostic data includes a lower threshold value, and the logic circuit determines that an abnormality occurs when the digital signal falls below the lower threshold value. Coulomb counter circuit according to the above.   The coulomb counter circuit according to claim 11, wherein the A / D converter is a ΔΣ A / D converter. A single-ended input port for receiving analog signals
16. The coulomb counter circuit according to claim 11, wherein the first multiplexer receives the output signal of the amplifier, the signal of the input port, and the diagnostic voltage and selects one.   17. The coulomb counter circuit according to claim 11, wherein the logic circuit changes the threshold value according to a temperature of the coulomb counter circuit.   18. The coulomb counter circuit according to claim 11, wherein the coulomb counter circuit is integrated on a single semiconductor substrate. Battery,
A charging circuit for charging the battery;
A load of the battery;
The coulomb counter circuit according to any one of claims 11 to 18, which detects charge / discharge charges of the battery,
A remaining amount detecting circuit for detecting the remaining amount of the battery based on the output of the coulomb counter circuit;
An electronic device comprising:

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