JP2016011864A - Integrated circuit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an integrated circuit allowing inspection of magnetic characteristics with no primary conductor provided.SOLUTION: The integrated circuit comprises: a magnetic detection circuit 13 generating a differential voltage according to a working magnetic field; cancel coils COILa, COILb, COILc, COILd generating a magnetic field according to current when the current flows therethrough; a measurement part u1 measuring the current flowing through the cancel coils COILa, COILb, COILc, COILd by a differential voltage generated in the magnetic detection circuit 13 at which the magnetic field generated by the measured current acts; an inspection part u2, when inspection current flows through the cancel coils COILa, COILb, COILc, COILd to generate an inspection magnetic field, measuring a differential voltage generated in the magnetic detection circuit 13 at which the inspection magnetic field acts; and a circuit setting part setting a first mode for connecting the magnetic detection circuit 13 to the measurement part u1, or a second mode for connecting the magnetic detection circuit 13 to the inspection part u2.

Description

  The present invention relates to an integrated circuit used in, for example, a magnetic balanced current sensor.

  The magnetic balance type current sensor measures the current to be measured using an induced magnetic field caused by the current to be measured (see, for example, Patent Document 1). A magnetically balanced current sensor generally includes a primary conductor called a bus bar and an integrated circuit that detects a current to be detected flowing through the primary conductor. In order to measure the current to be measured with good accuracy, the primary conductor must be positioned with good accuracy relative to the integrated circuit.

JP 2013-047610 A

By the way, it is preferable that an integrated circuit used for a magnetic balance type current sensor is determined to be defective based on magnetic characteristics. However, in a state where the primary conductor is not provided, a desired external magnetic field cannot be applied to the integrated circuit, so that the magnetic characteristics of the integrated circuit cannot be inspected. For this reason, the magnetic characteristics of the integrated circuit are inspected after being assembled as a product. However, if a defective product is found at that time, there is a problem that the primary conductor incorporated in the defective product is wasted. It was.
The present invention has been made in view of such circumstances, and provides an integrated circuit capable of inspecting magnetic characteristics in a state where a primary conductor is not provided (for example, before being cut out from a wafer). Is one of the resolution issues.

  In order to solve the above-described problem, an integrated circuit according to one embodiment of the present invention is an integrated circuit used in a magnetic balanced current sensor that measures a current to be measured flowing in a primary conductor. A magnetic detection bridge circuit that generates a detection voltage; an inductor that generates a magnetic field according to the current when the current flows; and a magnetic field generated by the current to be measured acts to generate the detection voltage in the magnetic detection bridge circuit. And a test circuit for measuring the detection voltage generated in the magnetic detection bridge circuit when the test magnetic field acts to generate a test magnetic field by passing a test current through the inductor. A circuit, a first mode for connecting the magnetic detection bridge circuit and the measurement circuit, or the magnetic detection bridge circuit and the inspection circuit. Characterized in that it comprises a circuit setting unit for setting the second mode to continue, the.

According to this aspect, when the integrated circuit generates a test magnetic field by supplying a test current to the inductor included in the integrated circuit, a voltage (detection voltage) generated in the magnetic detection bridge circuit on which the test magnetic field is applied. Based on this detection voltage, it is possible to inspect the magnetic characteristics of the magnetic detection bridge circuit.
Conventionally, an integrated circuit without a primary conductor could not be inspected for magnetic characteristics, so inspection accuracy was inferior, but defective products were determined by inspecting characteristics other than magnetic characteristics. It was.
However, according to this aspect, even in an integrated circuit in a state before the primary conductor is provided (for example, a state before being cut out from the wafer), it is possible to inspect magnetic characteristics that can determine defective products with higher accuracy. It becomes possible.

An integrated circuit according to another aspect of the present invention is the integrated circuit according to the aspect, wherein the circuit setting unit switches one of the measurement circuit and the inspection circuit to the magnetic detection bridge circuit. It is characterized by including an element.
According to this aspect, the circuit setting unit that sets the integrated circuit to the first mode or the second mode is configured by the switch element. Accordingly, the integrated circuit can be set to the first mode or the second mode simply by supplying a predetermined control signal to the switch element.

An integrated circuit according to another aspect of the present invention is the integrated circuit according to the aspect, wherein the measurement circuit includes an operational amplifier to which the detection voltage generated in the magnetic detection bridge circuit is input, and the operational amplifier A resistance element for measurement that is connected to an output terminal and converts a current flowing through the inductor into a voltage; and the circuit setting unit is configured to change an output impedance of the operational amplifier in the measurement circuit in the second mode. It is set to high impedance.
According to this aspect, the measurement circuit includes an operational amplifier to which the detection voltage generated in the magnetic detection bridge circuit is input, and a measurement resistor that is connected to the output terminal of the operational amplifier and converts the current flowing through the inductor into a voltage. An element. In the second mode, the circuit setting unit sets the output impedance of the operational amplifier in the measurement circuit to a high impedance so that only the test circuit is magnetically connected without connecting the measurement circuit to the magnetic detection bridge circuit. Connect to the detection bridge circuit. That is, according to this aspect, it is possible to set the integrated circuit to the first mode or the second mode only by supplying a control signal for setting the output impedance of the operational amplifier of the measurement circuit to high impedance to the operational amplifier. It becomes.

An integrated circuit according to another aspect of the present invention is the integrated circuit according to the aspect, wherein the measurement circuit and the inspection circuit include an operational amplifier to which the detection voltage generated in the magnetic detection bridge circuit is input. A resistance element for measurement for converting the current flowing through the inductor into a voltage; and a resistance element for inspection for amplifying an input voltage to the operational amplifier at a predetermined amplification factor and outputting the amplified voltage from the operational amplifier. In the first mode, the circuit setting unit connects an output terminal of the operational amplifier and the resistance element for measurement in the first mode, and inputs the operational amplifier in the second mode. A switching element for connecting the inspection resistance element between a terminal and an output terminal is included.
According to this aspect, since the measurement circuit and the inspection circuit can be provided as a single circuit, the circuit configuration can be further simplified.

The figure which shows the example of 1 structure of a magnetic balance type current sensor provided with the integrated circuit which concerns on 1st Embodiment of this invention. The figure which shows the example of 1 structure (in normal mode) of the integrated circuit which concerns on 1st Embodiment of this invention. The figure which shows the example of 1 structure (at the time of test | inspection mode) of the integrated circuit which concerns on 1st Embodiment of this invention. The figure which shows the structural example (at the time of a normal mode) of the integrated circuit which concerns on 2nd Embodiment of this invention. The figure which shows the structural example (at the time of test | inspection mode) of the integrated circuit which concerns on 2nd Embodiment of this invention. The figure which shows the example of 1 structure (at the time of a normal mode) of the integrated circuit which concerns on 3rd Embodiment of this invention. The figure which shows the structural example (at the time of test | inspection mode) of the integrated circuit which concerns on 3rd Embodiment of this invention.

[First Embodiment]
Embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a diagram showing a configuration example of a magnetic balanced current sensor including an integrated circuit according to the first embodiment of the present invention. As shown in the figure, the magnetic balanced current sensor 1 includes an integrated circuit 10 called, for example, an IC (Integrated Circuit) chip, and a primary conductor 50 called a bus bar (BUS BAR).
The integrated circuit 10 includes a magnetic detection circuit 13, a measurement / inspection circuit 15, a power supply terminal T1, an inspection current input terminal T2, an output terminal T3, a first control signal input terminal T4, and a ground terminal T5. Prepare.

The power supply terminal T1 is a terminal to which the power supply voltage VDD is input. The inspection current input terminal T2 is a terminal to which an inspection current Itest used when inspecting the magnetic characteristics of the integrated circuit 10 is input. The output terminal T3 is a terminal from which a voltage corresponding to a differential voltage Vsub described later is output. The first control signal input terminal T4 is a terminal to which a first control signal CTL1 described later is input. The ground terminal T5 is a terminal to which a ground potential supplied to each part of the integrated circuit 10 is input.
The magnetic characteristics of the integrated circuit 10 mean, for example, the magnetic characteristics of the magnetic detection circuit 13.

The magnetic detection circuit 13 is connected (inserted) between a cancel coil (inductor) COILa, COILb, COILc, COILd connected to the measurement / inspection circuit 15 and between the power supply terminal T1 and the ground terminal T5, thereby forming a bridge circuit. And magnetoresistive elements GMRa, GMRb, GMRc, and GMRd.
The magnetoresistive elements GMRa, GMRb, GMRc, and GMRd are sensor elements whose electrical characteristics (electrical resistance) change according to the magnetic field acting on themselves, and are used to detect the magnetic field. In this example, as the magnetoresistive elements GMRa, GMRb, GMRc, and GMRd, for example, giant magnetoresistive effect (GMR) elements are used.

  Note that when a magnetic field acts on a bridge circuit (magnetic detection bridge circuit) constituted by the magnetoresistive elements GMRa, GMRb, GMRc, and GMRd, a voltage corresponding to the magnetic field (a differential voltage Vsub, which will be described later) is applied to the nodes n1 and n2. Occurs between.

Incidentally, the integrated circuit 10 has a substantially rectangular shape when viewed in plan as shown in FIG. 1, for example, and is provided with magnetoresistive elements GMRa and GMRb along one side thereof, and the other side facing the one side. Are provided with magnetoresistive elements GMRc and GMRd.
Here, the magnetoresistive elements GMRa, GMRb, GMRc, and GMRd are connected as follows. That is, the magnetoresistive element GMRa and the magnetoresistive element GMRd are connected in series, and the magnetoresistive element GMRb and the magnetoresistive element GMRc are connected in series. The magnetoresistive elements GMRa and GMRd and the magnetoresistive elements GMRb and GMRc are connected (interposed) in parallel to the power supply terminal T1 and the ground terminal T5.

The primary conductor 50 is a substantially U-shaped conductor in plan view through which the measured current Ib measured by the magnetic balanced current sensor 1 flows. In the example shown in FIG. 1, the measured current Ib flows from the positive end I + of the primary conductor 50 toward the negative end I−.
Accordingly, in the example shown in FIG. 1, the measured current Ib flows in one direction on the left side of the magnetoresistive elements GMRa, b, and flows in the opposite direction to the right side of the magnetoresistive elements GMRc, d. Therefore, the magnetic field Hb generated due to the current Ib to be measured acts in the opposite direction between the magnetoresistive elements GMRa, b and the magnetoresistive elements GMRc, d.
That is, when the direction of the magnetic field Hb acting on the magnetoresistive elements GMRa and GMRb is the first direction, the direction of the magnetic field Hb acting on the magnetoresistive elements GMRc and GMRd is a second direction opposite to the first direction. .

Here, in the magnetoresistive elements GMRa, GMRb, GMRc, and GMRd, the value of electric resistance (impedance) increases when an external magnetic field in the first direction acts, and the electric resistance (impedance) increases when an external magnetic field in the second direction acts. An element whose value decreases.
Accordingly, in the example illustrated in FIG. 1, the potential of the node n1 rises and the potential of the node n2 falls, and thus the differential voltage Vsub expressed as the difference between the potential of the node n1 and the potential of the node n2 rises.

  That is, when the measured current Ib flows from the positive end I + to the negative end I− of the primary conductor 50, a differential voltage Vsub is generated according to the magnitude of the measured current Ib, and the cancel coils COILa, COILb, COILc. , COILd carries current. As will be described in detail later, the current that flows due to the generation of the differential voltage Vsub is converted into a voltage by the measurement / inspection circuit 15 and output from the output terminal T3. Based on the value output from the output terminal T3, the measured current Ib is measured.

By the way, the cancel coils COILa, COILb, COILc, COILd generate a magnetic field Hc in the opposite direction to the external magnetic field (magnetic field Hb) acting on the corresponding magnetoresistive elements GMRa, GMRb, GMRc, GMRd when current flows. Is provided. In the present embodiment, as shown in FIG. 1, the cancel coil COILa corresponds to the magnetoresistive element GMRa, the cancel coil COILb corresponds to the magnetoresistive element GMRb, and the cancel coil COILc corresponds to the magnetoresistive element GMRc. The cancel coil COILd corresponds to the magnetoresistive element GMRd.
Therefore, when the above-described differential voltage Vsub is generated, the external magnetic field (magnetic field Hb) acting on the magnetoresistive elements GMRa, GMRb, GMRc, GMRd is canceled (cancelled) by the magnetic field Hc by the cancel coils COILa, COILb, COILc, COILd. Until this occurs, a current (referred to as a cancel current Ican) flows through the cancel coils COILa, COILb, COILc, and COILd.

ここで（式1）中の「SENS」は当該磁気平衡式電流センサー１の感度である。 When the cancel current Ican such that the magnetic field Hb caused by the current Ib to be measured is canceled by the magnetic field Hc caused by the cancel coils COILa, COILb, COILc, and COILd flows through the cancel coils COILa, COILb, COILc, and COILd, The current flowing through the detection circuit 13 and the measurement / inspection circuit 15 is stabilized when the differential voltage Vsub becomes substantially zero. The cancel current Ican at this time is converted into a voltage by the measurement / inspection circuit 15, and a voltage (output voltage Vout) corresponding to the cancel current Ican is output to the output terminal T3.
Here, the relationship of the following (formula 1) exists between the output voltage Vout and the measured current Ib. Therefore, the measured current Ib can be obtained by substituting the value of the output voltage Vout output to the output terminal T3 into (Equation 1).

Here, “SENS” in (Equation 1) is the sensitivity of the magnetic balanced current sensor 1.

  FIG. 2 is a diagram illustrating a configuration example of the integrated circuit 10 according to the first embodiment of the present invention. Hereinafter, the circuit configuration of the measurement / inspection circuit 15 in the “normal mode (first mode)” will be described in detail with reference to FIG. The “normal mode” is a mode for measuring the measured current Ib described above.

The measurement / inspection circuit 15 includes a normal measurement unit (measurement circuit) u1 including a measurement operational amplifier OP1 and a voltage conversion resistor (measurement resistance element) R _COIL , an inspection operational amplifier OP2, and resistors R3, R4, R5. An inspection unit (inspection circuit) u2 including R6, a constant voltage supply unit u3 which is a voltage follower circuit by a constant voltage supply operational amplifier OP3, and an intermediate potential generation for generating an intermediate potential (VDD / 2) from the power supply potential VDD Unit u4, switch SW1 for connecting output terminal T3 and normal measurement unit u1 or inspection unit u2, and switch SW2 for connecting magnetic detection circuit 13 to normal measurement unit u1 or inspection current input terminal T2.
Here, since the inspection current input terminal T2 is a terminal related to the function of the inspection unit u2, if it is regarded as a part of the inspection unit u2, the switch SW1 and the switch SW2 are, as shown in FIG. It can be said that either one of the inspection units u2 constitutes a switch that connects to the magnetic detection circuit 13.

As shown in FIG. 2, in the normal mode, the switch SW1 is set to connect the output terminal T3 and the normal measurement unit u1, and the switch SW2 connects the magnetic detection circuit 13 and the normal measurement unit u1. Set to
In the “inspection mode (second mode)” described later, the switch SW1 is set to connect the output terminal T3 and the inspection unit u2, and the switch SW2 is connected to the magnetic detection circuit 13 and the inspection current input terminal T2. And is set to connect. The inspection mode is a mode for measuring (inspecting) the magnetic characteristics of the magnetic detection circuit 13 (magnetoresistive elements GMRa, GMRb, GMRc, GMRd).

As described above, the switches SW1 and SW2 function as a circuit setting unit that sets the normal mode (first mode) or the inspection mode (second mode).
The setting of the switches SW1 and SW2 is switched by the first control signal CTL1 input from the first control signal input terminal T4. For example, when the high-level first control signal CTL1 is supplied to the switches SW1 and SW2, the switches SW1 and SW2 are switched to the settings shown in FIG. 2, and the integrated circuit 10 is set to the normal mode.

In the normal measurement unit u1, the potential of the node n1 of the magnetic detection circuit 13 described above is input to the non-inverting input terminal of the measurement operational amplifier OP1, and the potential of the node n2 is input to the inverting input terminal of the measurement operational amplifier OP1. Is done. That is, the differential voltage Vsub described above is input to the measurement operational amplifier OP1. The cancel current Ican flowing from the output terminal of the measurement operational amplifier OP1 toward the magnetic detection circuit 13 is converted into a voltage (output voltage Vout) by the voltage conversion resistor R _COIL and output to the output terminal T3. The output voltage Vout is a value corresponding to the magnitude of the measured current Ib, and the value of the measured current Ib can be obtained by substituting the value of the output voltage Vout into the above-described (Equation 1).

The inspection unit u2 does not form a closed circuit in the normal mode, and no current flows through the inspection unit u2. The configuration of the inspection unit u2 will be described in detail later with reference to FIG. 3 showing the circuit configuration in the “inspection mode”.
In the constant voltage supply unit u3, the intermediate potential (VDD / 2) generated by the intermediate potential generation unit u4 is input to the non-inverting input terminal of the constant voltage supply operational amplifier OP3, and the output terminal of the constant voltage supply operational amplifier OP3. The potential of the node n3 on the side becomes (VDD / 2), and the intermediate potential (VDD / 2) is supplied to one end of the cancel coil COILb of the magnetic detection circuit 13. That is, the configuration in which the constant voltage supply unit u3 and the intermediate potential generation unit u4 are combined becomes a constant voltage source that outputs the intermediate potential (VDD / 2) to one end of the cancel coil COILb.

  The intermediate potential generation unit u4 divides the power supply potential VDD by the resistors R1 and R2 having substantially the same resistance value, and generates an intermediate potential (VDD / 2). The potential of the node n4 becomes an intermediate potential (VDD / 2).

FIG. 3 is a diagram illustrating a configuration example of the integrated circuit 10 in the inspection mode. Hereinafter, the circuit configuration of the measurement / inspection circuit 15 in the inspection mode will be described in detail with reference to FIG.
As shown in FIG. 3, in the inspection mode, the switch SW1 is set so as to connect the output terminal T3 and the inspection unit u2, and the switch SW2 connects the inspection current input terminal T2 and the magnetic detection circuit 13. Set to
The setting of the switches SW1 and SW2 is switched by the first control signal CTL1 input from the first control signal input terminal T4. For example, when the low-level first control signal CTL1 is supplied to the switches SW1 and SW2, the switches SW1 and SW2 are switched to the settings shown in FIG. 3, and the integrated circuit 10 is set to the inspection mode.
The normal measurement unit u1 does not form a closed circuit in the inspection mode, and no current flows through the normal measurement unit u1.

The inspection unit u2 includes an inspection operational amplifier OP2, a resistor R3 connected between the inverting input terminal of the inspection operational amplifier OP2 and the node n2, and a non-inverting input terminal of the inspection operational amplifier OP2 and the node n1. A resistor R4 connected in between, a resistor R5 connected between the output terminal and the inverting input terminal of the test operational amplifier OP2, and a non-inverting input terminal of the test operational amplifier OP2 and the node n5. Resistor R6. With this configuration, the inspection unit u2 functions as an amplifier circuit, and its amplification factor (gain) is (R5 / R3) times.
In the inspection mode, the output terminal of the operational amplifier OP2 for inspection is connected to the output terminal T3 of the integrated circuit 10 as shown in FIG. Further, the node n5 is connected to the node n3 of the constant voltage supply unit u3, and the potential thereof is an intermediate potential (VDD / 2), like the node n3.
The resistance value of the resistor R3 and the resistance value of the resistor R4 are equal, and the resistance value of the resistor R5 and the resistance value of the resistor R6 are equal.

In the inspection mode, the inspection current Itest is input from the inspection current input terminal T2 to the magnetic detection circuit 13 and flows to the cancel coils COILa, COILb, COILc, COILd, and the cancel coils COILa, COILb, COILc, COILd apply the magnetic field Hc ′. Occur.
Here, in the cancel coils COILa, COILb, COILc, COILd, the direction of the magnetic field Hc ′ acting on the magnetoresistive elements GMRa, GMRb and the magnetic field Hc ′ acting on the magnetoresistances GMRc, GMRd are opposite to each other. It is provided in an aspect.

  As described above, the magnetoresistive elements GMRa, GMRb, GMRc, and GMRd increase in the value of electric resistance (impedance) when an external magnetic field in the first direction acts, and electric resistance (impedance) when an external magnetic field in the second direction acts. This is a device whose value decreases. Therefore, when the magnetic field Hc ′ acts on the magnetoresistive elements GMRa, GMRb, GMRc, and GMRd, a difference occurs between the potential of the node n1 and the potential of the node n2, and the differential voltage Vsub ′ increases.

At this time, the potential of the node n2 is input to the inverting input terminal via the resistor R3 and the potential of the node n1 is input to the non-inverting input terminal via the resistor R4 to the test operational amplifier OP2. A potential corresponding to the differential voltage Vsub ′ is output to the output terminal of the inspection operational amplifier OP2. An output voltage Vout ′ corresponding to the differential voltage Vsub ′ is output to the output terminal T3. Specifically, the output voltage Vout ′ in the inspection mode is expressed by the following (Equation 2).

  Here, the relationship between the magnetic field Hc ′ and the differential voltage Vsub ′ is known to the manufacturer of the integrated circuit 10. In other words, the relationship between the inspection current Itest and the output voltage Vout ′ is known. Therefore, by determining whether or not the value of the output voltage Vout ′ output from the output terminal T3 is a value corresponding to the test current Itest passed from the test current input terminal T2 to the magnetic detection circuit 13, the integrated circuit Good / bad of 10 magnetic characteristics (for example, magnetic characteristics of magnetoresistive elements GMRa, GMRb, GMRc, GMRd) can be determined.

As described above, according to the first embodiment of the present invention, the magnetic characteristics can be obtained in a state where the primary conductor (primary conductor 50 shown in FIG. 1) is not provided (for example, before being cut out from the wafer). An inspectable integrated circuit 10 can be provided.
Conventionally, an integrated circuit without a primary conductor could not be inspected for magnetic characteristics, so inspection accuracy was inferior, but defective products were determined by inspecting characteristics other than magnetic characteristics. It was.
However, according to this aspect, even in an integrated circuit in a state before providing a primary conductor (for example, a state before being cut out from a wafer), a defective product can be discriminated with high accuracy by inspecting magnetic characteristics. .

[Second Embodiment]
Hereinafter, an integrated circuit according to a second embodiment of the present invention will be described. FIG. 4 is a diagram illustrating a configuration example (in the normal mode) of the integrated circuit according to the second embodiment. FIG. 5 is a diagram illustrating a configuration example (in an inspection mode) of the integrated circuit according to the second embodiment.
The main difference between the integrated circuit 10 according to the first embodiment and the integrated circuit 10-1 according to the second embodiment is that the measurement / inspection circuit 15-1 is used instead of the measurement / inspection circuit 15 in the second embodiment. It is a point to use. In addition, in order to avoid duplication description, the same code | symbol is attached | subjected to the structure same as the integrated circuit 10 which concerns on 1st Embodiment, and the description is abbreviate | omitted suitably.

The measurement / inspection circuit 15-1 of the second embodiment is not provided with the switches SW1 and SW2 of the first embodiment, and is provided with a normal measurement unit u1-1 instead of the normal measurement unit u1. Yes. The normal measurement unit u1-1 includes a first operational amplifier OP1 to which the differential voltage Vsub is input, and a voltage conversion resistor R _COIL connected to the output terminal of the first operational amplifier OP1, and the first operational amplifier OP1. Is configured such that a second control signal CTL2 for setting its output impedance to high impedance can be input.

The integrated circuit 10-1 includes a second control signal input terminal T6 to which the above-described second control signal CTL2 is input, and a test output terminal T7 from which the output voltage Vout ′ in the test mode is output. It has been.
Here, when the second control signal CTL2 set to a low level, for example, is supplied to the first operational amplifier OP1 via the second control signal input terminal T6, the output impedance of the first operational amplifier OP1 is low impedance. The first operational amplifier OP1 amplifies the input signal and outputs it. When the second control signal CTL2 set to the high level is supplied to the first operational amplifier OP1, the output impedance of the first operational amplifier OP1 is set to high impedance, and the first operational amplifier OP1 is input. Stops amplification of the received signal.

In the integrated circuit 10-1 according to the second embodiment, when the output impedance of the first operational amplifier OP1 is low impedance, the measurement / inspection circuit 15-1 has the circuit configuration shown in FIG. As in the mode, the output voltage Vout is output to the output terminal T3.
On the other hand, when the output impedance of the first operational amplifier OP1 is high impedance, the measurement / inspection circuit 15-1 has the circuit configuration shown in FIG. That is, the normal measurement unit u1-1 does not form a closed circuit, and the output voltage Vout ′ is output from the inspection unit u2 by flowing the inspection current Itest from the output terminal T3 as in the inspection mode in the first embodiment. Circuit configuration.
However, in the second embodiment, the output voltage Vout ′ is output to the inspection output terminal T7. This is different from the first embodiment in which the output voltage Vout ′ is output to the output terminal T3.

As described above, according to the second embodiment of the present invention, the same effect as the integrated circuit 10 according to the first embodiment can be obtained, and the switches SW1 and SW2 in the first embodiment need not be provided. Thus, the circuit configuration can be simplified.
As described above, in the integrated circuit 10-1 according to the second embodiment, when the second control signal input terminal T6 and the second control signal CTL2 set to the high level are supplied, the output impedance becomes high impedance. The switched first operational amplifier OP1 functions as a circuit setting unit for setting the integrated circuit 10-1 to the normal mode (first mode) or the inspection mode (second mode).

[Third Embodiment]
Hereinafter, an integrated circuit according to a third embodiment of the present invention will be described. FIG. 6 is a diagram illustrating a configuration example (in a normal mode) of the integrated circuit according to the third embodiment. FIG. 7 is a diagram illustrating a configuration example (in an inspection mode) of the integrated circuit according to the third embodiment.
The main difference between the integrated circuit 10 according to the first embodiment and the integrated circuit 10-2 according to the third embodiment is that a measurement / inspection circuit 15-2 is used instead of the measurement / inspection circuit 15. In addition, in order to avoid duplication description, the same code | symbol is attached | subjected to the structure same as the integrated circuit 10 which concerns on 1st Embodiment, and the description is abbreviate | omitted suitably.

The measurement / inspection circuit 15-2 includes a normal measurement / inspection unit u5 instead of the normal measurement unit u1 and the inspection unit u2 in the first embodiment, and instead of the switches SW1 and SW2 in the first embodiment. Switches SW3, SW4 and SW5 are provided.
The normal measurement / inspection unit u5 includes a normal measurement / inspection operational amplifier OP4 to which the differential voltage Vsub is input, a voltage conversion resistor R _COIL connected to the output terminal of the normal measurement / inspection operational amplifier OP4, and a switch SW3. , SW4, SW5 and resistors R3, R4, R5, R6. Further, the integrated circuit 10-2 includes a third control signal input terminal T8 to which a third control signal CTL3 for controlling switching of the switches SW3, SW4, SW5 is input.

The resistor R3 is connected between the inverting input terminal of the normal measurement / inspection operational amplifier OP4 and the node n2. The resistor R4 is connected between the non-inverting input terminal of the normal measurement / inspection operational amplifier OP4 and the node n1. The resistor (test resistor element) R5 is connected between the output terminal and the inverting input terminal of the normal measurement / test operational amplifier OP4. The resistor (test resistor element) R6 is connected between the non-inverting input terminal of the normal measurement / test operational amplifier OP4 and the node n5.
The switch SW3 is a switch that connects the voltage conversion resistor R _COIL to the output terminal or the inspection current input terminal T2 of the normal measurement / inspection operational amplifier OP4. The switch SW4 is a switch for switching connection / disconnection between the output terminal of the normal measurement / inspection operational amplifier OP4 and the resistor R5. The switch SW5 is a switch that switches connection / disconnection between the resistor R6 and the node n5.

In the normal mode, as shown in FIG. 6, the output terminal of the normal measurement / inspection operational amplifier OP4 is connected to the voltage conversion resistor R _COIL by the switch SW3, and the magnetic detection circuit 13 is connected via the voltage conversion resistor R _COIL. Connected with. On the other hand, the switch SW4 is turned off and the resistor R5 is disconnected, and the switch S5 is also turned off and the resistor R6 is also disconnected. The differential voltage Vsub is input to the normal measurement / inspection operational amplifier OP4.
That is, in the normal mode, the normal measurement / inspection unit u5 has a configuration corresponding to the normal measurement unit u1 in the first embodiment.

On the other hand, in the inspection mode, as shown in FIG. 7, since the inspection current input terminal T2 and the voltage conversion resistor _RCOIL are connected by the switch SW3, the inspection current input terminal T2 is connected via the voltage conversion resistor _RCOIL. And the magnetic detection circuit 13 are connected. Further, the switch SW4 is turned on, and the output terminal of the normal measurement / inspection operational amplifier OP4 is connected to the resistor R5 as shown in FIG. 7, and the output of the normal measurement / inspection operational amplifier OP4 is connected through the resistor R5. The terminal and the inverting input terminal are connected. Further, the switch SW5 is turned on, and the non-inverting input terminal of the normal measurement / inspection operational amplifier OP4 is connected to the node n5 through the resistor R6.
That is, in the inspection mode, the normal measurement / inspection unit u5 has a configuration corresponding to the inspection unit u2 that functions as an amplifier in the first embodiment.

As described above, the switches SW3, SW4, and SW5 function as a circuit setting unit that sets the normal mode (first mode) or the inspection mode (second mode).
The setting of these switches SW3, SW4, SW5 is switched by a third control signal CTL3 input from the third control signal input terminal T8.
For example, when the high-level third control signal CTL3 is supplied to the switches SW3, SW4, SW5, the switches SW3, SW4, SW5 are switched to the settings shown in FIG. 6, and the integrated circuit 10-2 is set to the normal mode. Is done. On the other hand, when the low-level third control signal CTL3 is supplied to the switches SW3, SW4, and SW5, the switches SW3, SW4, and SW5 are switched to the settings shown in FIG. 7, and the integrated circuit 10-2 enters the inspection mode. Is set.

  In the integrated circuit 10-2 according to the third embodiment, in both the normal mode and the inspection mode, the output terminal of the normal measurement / inspection operational amplifier OP4 is connected to the output terminal T3 of the integrated circuit 10-2. Connected. Therefore, in the normal mode, the output voltage Vout is output to the output terminal T3, and in the inspection mode, the output voltage Vout ′ is output to the output terminal T3.

  As described above, according to the third embodiment, the same effect as that of the integrated circuit 10 according to the first embodiment can be obtained, and the number of operational amplifiers can be reduced. This simplification is realized.

DESCRIPTION OF SYMBOLS 1 ... Magnetic balance type current sensor 10, 10-1, 10-2 ... Integrated circuit, 13 ... Magnetic detection circuit, 15, 15-1, 15-2 ... Measurement / inspection circuit, 50 ... Primary conductor, COILa, COILb , COILc, COILd ... cancellation coil, GMRa, GMRb, GMRc, GMRd ... magnetoresistive element, Hb, Hc, Hc '... magnetic field, OP1 ... operational amplifier for measurement, OP2 ... operational amplifier for inspection, OP3 ... computation for constant voltage supply Amplifier, OP4 ... Operational amplifier for normal measurement / inspection, T1 ... Power supply terminal, T2 ... Inspection current input terminal, T3 ... Output terminal, T4 ... First control signal input terminal, T5 ... Ground terminal, T6 ... Second control signal input Terminal, T7: inspection output terminal, T8: third control signal input terminal, u1, u1-1: normal measurement unit, u2: inspection unit, u3: constant voltage supply unit, u4: intermediate potential generation unit, u5: normal measurement And inspection unit.

Claims (4)

An integrated circuit used in a magnetic balance type current sensor for measuring a current to be measured flowing in a primary conductor,
A magnetic detection bridge circuit that generates a detection voltage according to the magnetic field when the magnetic field acts;
An inductor that generates a magnetic field according to the current when the current flows;
A measurement circuit that measures the current that flows through the inductor when the detection voltage is generated in the magnetic detection bridge circuit on which the magnetic field generated by the current to be measured acts;
An inspection circuit that measures the detection voltage generated in the magnetic detection bridge circuit on which the inspection magnetic field has acted when an inspection current is caused to flow through the inductor to generate the inspection magnetic field;
A circuit setting unit for setting the first mode for connecting the magnetic detection bridge circuit and the measurement circuit, or the second mode for connecting the magnetic detection bridge circuit and the inspection circuit;
An integrated circuit comprising: The circuit setting unit includes a switch element that connects either the measurement circuit or the inspection circuit to the magnetic detection bridge circuit.
The integrated circuit according to claim 1. The measurement circuit includes:
An operational amplifier to which the detection voltage generated in the magnetic detection bridge circuit is input;
A resistance element for measurement connected to the output terminal of the operational amplifier and converting a current flowing through the inductor into a voltage;
The circuit setting unit sets the output impedance of the operational amplifier in the measurement circuit to high impedance in the second mode.
The integrated circuit according to claim 1. The measurement circuit and the inspection circuit are:
An operational amplifier to which the detection voltage generated in the magnetic detection bridge circuit is input;
A resistance element for measurement that converts a current flowing through the inductor into a voltage;
A resistance element for inspection for amplifying an input voltage to the operational amplifier at a predetermined amplification factor and outputting the amplified voltage from the operational amplifier;
A single circuit comprising:
The circuit setting unit connects the output terminal of the operational amplifier and the resistance element for measurement in the first mode, and between the input terminal and the output terminal of the operational amplifier in the second mode. Including a switch element for connecting the inspection resistance element,
The integrated circuit according to claim 1.

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