JP6568825B2 - Control circuit and current sensor - Google Patents

Description

  The present invention relates to a control circuit and a current sensor.

Conventionally, in a compound semiconductor current sensor having a magnetic sensor, it is known to perform temperature compensation of the output of the magnetic sensor (see, for example, Patent Documents 1 and 2).
Patent Document 1 Japanese Patent Application Laid-Open No. 2004-53505 Patent Document 2 Japanese Patent Application Laid-Open No. 3-261869

  However, the conventional current sensor cannot sufficiently compensate the temperature characteristics of the magnetic sensor.

In the first aspect of the present invention, in the control circuit for controlling the magnetic sensor having the Hall element, the first resistance element is used to convert the potential difference between both ends in the drive direction of the Hall element into the current I _vh. / I conversion circuit, current I _vh , reference current I _ref , and current I _h in the driving direction of the Hall element, the value of I _h · I _ref / I _vh or I _vh · I _ref / I _h A calculation circuit that outputs the calculation result used, and a temperature compensation circuit that compensates for the influence of the temperature on the output of the Hall element based on the calculation result, and the reference current I _ref has a resistance corresponding to the second resistance element, Provided is a control circuit that is generated based on a predetermined reference voltage V _ref .

  In the second aspect of the present invention, a conductor through which a current to be measured flows, a Hall element that is formed of a compound semiconductor and outputs a signal corresponding to the current to be measured, and a voltage value or a current value detected from the Hall element are used. And a control circuit that compensates for the influence of temperature on the output of the Hall element, and the conductor provides a current sensor formed closer to the Hall element than the control circuit.

  The summary of the invention does not enumerate all the features of the present invention. In addition, a sub-combination of these feature groups can also be an invention.

1 shows an outline of a configuration of a current sensor 100 according to a first embodiment. 1 shows an exemplary configuration of a current sensor 100 according to a first embodiment. An example of the structure of the current sensor 500 which concerns on the comparative example 1 is shown. An example of the structure of the current sensor 100 which concerns on Example 2 is shown. An example of the structure of the current sensor 100 which concerns on Example 3 is shown. An example of the structure of the current sensor 100 which concerns on Example 4 is shown. An example of the structure of the current sensor 100 which concerns on Example 5 is shown. 18 shows an exemplary configuration of a current sensor 100 according to a seventh embodiment. 18 shows an exemplary configuration of a current sensor 100 according to an eighth embodiment. 18 shows an example of the configuration of an ammeter of a current sensor 100 according to an eighth embodiment. 10 shows an example of the configuration of a current sensor 100 according to a ninth embodiment. An example of the structure of the current sensor 100 according to Example 10 is shown. An example of the structure of the current sensor 100 according to Example 11 is shown. An example of the structure of the current sensor 100 according to Example 12 is shown. An example of the structure of the current sensor 100 according to Example 13 is shown. An example of the structure of the current sensor 100 according to Example 14 is shown. An example of a specific configuration of the current sensor 100 is shown.

  Hereinafter, the present invention will be described through embodiments of the invention, but the following embodiments do not limit the invention according to the claims. In addition, not all the combinations of features described in the embodiments are essential for the solving means of the invention.

[Example 1]
FIG. 1 shows an outline of a configuration of a current sensor 100 according to the first embodiment. The current sensor 100 includes a magnetic sensor 10, a control circuit 20, and a conductor 30.

The magnetic sensor 10 outputs an output signal S _o detected according to the measured current I _o . The magnetic sensor 10 of this example detects a change in the magnetic field due to the current _Io to be measured flowing in the vicinity of the magnetic sensor 10. In one example, the magnetic sensor 10 includes a Hall element formed of a compound semiconductor. In this case, the magnetic sensor 10 outputs a voltage corresponding to the change of the magnetic field as the output signal _So. The driving method when the magnetic sensor 10 has a Hall element may be constant current driving or constant voltage driving.

The control circuit 20 detects the detection signal S _d according to the drive state of the magnetic sensor 10. In one example, the detection signal S _d is a voltage value or a current value detected from the magnetic sensor 10. The detection signal S _d may include a driving voltage or a driving current for driving the magnetic sensor 10. The control circuit 20 based on the detection signal S _d, and outputs a control signal S _c for compensating the temperature characteristic of the magnetic sensor 10 in the magnetic sensor 10. Further, the control circuit 20 may estimate the temperature of the magnetic sensor 10 based on the voltage value and the current value detected from the magnetic sensor 10. The control circuit 20, the control signal S _c, in order to cancel the temperature characteristic of the magnetic sensor 10, to adjust the sensitivity or offset of the current sensor 100.

Conductor 30 is a conductor of flow of current to be measured _{I o} of the current sensor 100 measures. By the measurement current I _o flows in the conductor 30, the magnetic field of the magnetic sensor 10 changes. Therefore, the conductor 30 is arranged close to the magnetic sensor 10 to such an extent that the magnetic field of the magnetic sensor 10 changes. That is, the current sensor 100 of the present embodiment has no core in the vicinity of the magnetic sensor 10, a coreless current sensor for detecting directly the measured current I _o flowing through the conductor 30.

When the current sensor 100 is a coreless type, a temperature difference may occur between the magnetic sensor 10 in the vicinity of the conductor 30 through which the current _Io to be measured flows and the control circuit 20 separated from the conductor 30. The current sensor 100 of this example directly measures the temperature of the magnetic sensor 10 as the temperature used for canceling the temperature characteristic. Thereby, the current sensor 100 can cancel the temperature characteristic of the magnetic sensor 10 with high accuracy. In the present specification, directly measuring the temperature of the magnetic sensor 10 refers to measuring the temperature of the magnetic sensor 10 based on information dependent on the temperature of the magnetic sensor 10. That is, the method for directly measuring the temperature of the magnetic sensor 10 is not particularly limited as long as it can measure the temperature of the magnetic sensor 10.

[Example 1]
FIG. 2 shows an example of the configuration of the current sensor 100 according to the first embodiment. The control circuit 20 of this example includes an adjustment circuit 40 and a signal processing circuit 50.

Adjusting circuit 40 generates a control signal _{S c} in accordance with the detection signal _{S d} of the magnetic sensor 10. The adjustment circuit 40 adjusts the operation of the magnetic sensor 10 by outputting the generated control signal _Sc to the magnetic sensor 10. In one example, the control signal S _c is the time constant current drive, adjusts the driving current of the magnetic sensor 10. The control signal S _c is the time constant voltage drive may adjust the driving voltage of the magnetic sensor 10. Thereby, the adjustment circuit 40 adjusts so that the sensitivity of the current sensor 100 becomes constant regardless of the temperature.

The signal processing circuit 50 outputs the output signal _So of the magnetic sensor 10 to the output terminal OUT. In one example, the signal processing circuit 50 amplifies the output signal _So with a predetermined gain and outputs the amplified signal to the output terminal OUT. The signal processing circuit 50 may adjust the gain according to the temperature of the magnetic sensor 10 estimated by the adjustment circuit 40.

[Comparative Example 1]
FIG. 3 shows an example of the configuration of the current sensor 500 according to the first comparative example. The current sensor 500 of this example includes a Hall element 510, a temperature sensor 520, an adjustment circuit 540, and a signal processing circuit 550.

  The temperature sensor 520 is provided outside the Hall element 510 and measures the temperature inside the current sensor 500. The adjustment circuit 540 adjusts the drive current of the Hall element 510 based on the temperature measured by the temperature sensor 520.

The current sensor 500 of this example is a coreless type current sensor having a built-in conductor 530 through which the current to be measured _Io flows. Due to the heat generated by the conductor 530, the temperature of the Hall element 510 adjacent to the conductor 530 rises. Since the current sensor 500 measures the temperature inside the current sensor 500 using the temperature sensor 520 outside the Hall element 510, there is a difference between the temperature measured by the temperature sensor 520 and the actual temperature of the Hall element 510. Arise. Therefore, it is difficult for the current sensor 500 of this example to accurately adjust the temperature characteristics.

  The current sensor 500 includes two Hall elements 510, so that one of them can be used as a temperature measurement replica. However, the method using the replica of the Hall element 510 causes a temperature difference problem between the two Hall elements 510 and a mismatch problem between the two Hall elements 510. Further, when the two Hall elements 510 are provided, the cost of the current sensor 500 increases.

[Example 2]
FIG. 4 illustrates an example of the configuration of the current sensor 100 according to the second embodiment. The control circuit 20 of this example includes an adjustment circuit 40 and a signal processing circuit 50.

Adjusting circuit 40 based on the detection signal S _d that is input, and generates a gain adjustment signal S _g for adjusting the gain of the signal processing circuit 50. The gain adjustment signal _Sg is a signal corresponding to the temperature of the magnetic sensor 10 estimated by the adjustment circuit 40. For example, the gain adjustment signal _Sg is calculated by substituting the temperature of the magnetic sensor 10 into a predetermined calculation formula. The adjustment circuit 40 outputs the gain adjustment signal _Sg to the signal processing circuit 50.

The signal processing circuit 50 amplifies the output of the magnetic sensor 10 with a gain corresponding to the gain adjustment signal S _g. Thereby, the signal processing circuit 50 cancels the temperature characteristic of the current sensor 100. The current sensor 100 of this example is to adjust the gain of the signal processing circuit 50 by the gain adjustment signal S _g, like the current sensor 100 according to the first embodiment, the control of the magnetic sensor 10 by the control signal S _c You may operate in combination.

[Example 3]
FIG. 5 illustrates an example of a configuration of the current sensor 100 according to the third embodiment. The control circuit 20 of this example includes a Hall resistance measurement circuit 41, a temperature compensation circuit 42, and a signal processing circuit 50. The magnetic sensor 10 of this example includes a Hall element 11.

The Hall resistance measurement circuit 41 calculates a resistance value R _h of the Hall element 11 by a calculation based on the detection signal S _d . Further, Hall resistance measuring circuit 41 outputs a resistance value R _h of the Hall element 11 was measured, the temperature compensation circuit 42 as a resistance measuring signal S _r. Hall resistance measuring circuit 41 of the present embodiment is an example of a calculation circuit for outputting a calculation result according to the detection signal S _d. For example, the Hall resistance measurement circuit 41 calculates the resistance value R _h of the Hall element 11 based on the potential difference between both ends in the driving direction of the Hall element 11 or the current value in the driving direction.

  Here, the potential difference at both ends in the driving direction of the Hall element 11 or the current value in the driving direction is not limited to constant current driving or constant voltage driving, but is a potential difference or current value at both ends of the Hall element 11 in the driving direction of the Hall element 11. Point to. For example, in the case of constant current driving, the current values at both ends in the driving direction of the Hall element 11 correspond to the driving current. On the other hand, in the case of constant voltage driving, the potential difference between both ends in the driving direction of the Hall element 11 corresponds to the driving voltage. In this specification, the driving direction is a direction in which a driving current flows in the Hall element 11 in the case of constant current driving, and a direction in which a current corresponding to the driving voltage flows in the Hall element 11 in the case of constant voltage driving. is there.

The temperature compensation circuit 42 compensates the influence of the temperature on the output of the Hall element 11 based on the resistance measurement signal _Sr. In one example, the temperature compensation circuit 42 estimates the temperature of the Hall element 11 from the resistance measurement signal _Sr. For example, the temperature compensation circuit 42 estimates the temperature of the Hall element 11 by measuring in advance the resistance value R _h of the Hall element 11 for each temperature. Thereby, the temperature compensation circuit 42 compensates for the influence of temperature on the output of the Hall element 11.

Further, the temperature compensation circuit 42 outputs a control signal _Sc to the Hall element 11 based on the resistance measurement signal _Sr. Thereby, the temperature compensation circuit 42 adjusts the sensitivity of the current sensor 100 according to the temperature of the Hall element 11. For example, the temperature compensation circuit 42 cancels the temperature characteristic of the current sensor 100 by adjusting the drive current or drive voltage of the magnetic sensor 10.

[Example 4]
FIG. 6 illustrates an example of the configuration of the current sensor 100 according to the fourth embodiment. The control circuit 20 of this example includes a Hall resistance measurement circuit 41, a temperature compensation circuit 42, and a signal processing circuit 50. The temperature compensation circuit 42 of this example is different from the current sensor 100 according to the third embodiment in that the gain of the signal processing circuit 50 is adjusted based on the temperature of the magnetic sensor 10. The Hall resistance measurement circuit 41 of this example may operate in the same manner as the Hall resistance measurement circuit 41 according to other embodiments.

Temperature compensation circuit 42 based on the resistance measurement signal S _r of Hall resistance measuring circuit 41 has generated, to generate a gain adjustment signal S _g. The temperature compensation circuit 42 outputs the generated resistance measurement signal _Sr to the signal processing circuit 50 and adjusts the gain of the signal processing circuit 50. As a result, the temperature compensation circuit 42 cancels the temperature characteristics of the current sensor 100.

[Example 5]
FIG. 7 illustrates an example of the configuration of the current sensor 100 according to the fifth embodiment. The control circuit 20 of this example includes a Hall resistance measurement circuit 41, a temperature compensation circuit 42, a signal processing circuit 50, and a storage unit 60.

  The storage unit 60 stores in advance a gain or offset corresponding to a potential difference between both ends in the driving direction of the Hall element 11 or a current value in the driving direction. In one example, the storage unit 60 stores in advance an optimal drive current corresponding to the temperature of the magnetic sensor 10. In this specification, the optimal drive current refers to a drive current that makes the sensitivity of the current sensor 100 constant regardless of temperature. The storage unit 60 may include a memory for storing information.

Temperature compensation circuit 42, in response to the resistance measuring signal S _r from the Hall resistance measurement circuit 41 reads the drive current applied to a magnetic sensor 10 from the storage unit 60. That is, the temperature compensation circuit 42 reads the drive current corresponding to the resistance value of the magnetic sensor 10 measured by the Hall resistance measurement circuit 41 from the storage unit 60. The temperature compensation circuit 42 and the storage unit 60 of this example can be similarly applied to the second and fourth embodiments that adjust the gain of the signal processing circuit 50.

[Example 6]
The current sensor 100 according to the sixth embodiment has the same configuration as the current sensor 100 according to the fifth embodiment. However, the current sensor 100 has an adjustment process for storing information in the storage unit 60 during the shipping test process. The storage unit 60 of this example stores in advance information calculated during the shipping test process of the current sensor 100. For example, the storage unit 60 stores an optimum drive current corresponding to each of a plurality of environmental temperatures during the test process for each temperature.

  The current sensor 100 of this example reads out the drive current to be applied from the storage unit 60 in accordance with the temperature measurement value of the Hall resistance measurement circuit 41 during actual operation. The current sensor 100 operates the magnetic sensor 10 with the drive current read from the storage unit 60. Thereby, the current sensor 100 of this example can adjust the sensitivity temperature characteristic of the magnetic sensor 10 for each individual.

[Example 7]
FIG. 8 illustrates an example of the configuration of the current sensor 100 according to the seventh embodiment. The control circuit 20 of this example includes a Hall resistance measurement circuit 41, a temperature compensation circuit 42, a signal processing circuit 50, and a storage unit 60. The magnetic sensor 10 has a Hall element 11 that is driven at a constant current.

The Hall resistance measurement circuit 41 measures the resistance value R _h of the Hall element 11 based on the current I _h and the voltage V _h . The current I _h is a current value in the driving direction of the Hall element 11. That is, when the Hall element 11 is driven at a constant current, the current I _h becomes the drive current I _h . The voltage V _h is a voltage value at both ends in the driving direction of the Hall element 11. The voltage V _h is a drive voltage of the Hall element 11 when the Hall element 11 is driven at a constant voltage.

For example, the Hall resistance measurement circuit 41 calculates R _h = V _h / I _h based on the current I _h and the voltage V _h . Thereby, the Hall resistance measurement circuit 41 measures the resistance value R _h of the Hall element 11. Hall resistance measuring circuit 41, the measured resistance value R _h as a resistance measuring signal S _r, and output to the temperature compensation circuit 42.

The temperature compensation circuit 42 estimates the temperature in the Hall element 11 based on the resistance measurement signal _Sr. In one example, the temperature compensation circuit 42 estimates a temperature according to the resistance value R _h of the Hall element 11 based on information stored in advance in the storage unit 60. Further, the temperature compensation circuit 42 may be a circuit in which a relational expression is derived for each individual and stored in the storage unit 60 during the shipping test process.

The current source 70 supplies a drive current _Ih to the Hall element 11. Temperature compensation circuit 42 based on the resistance measurement signal S _r, the current source 70 controls the drive current I _h to give the Hall element 11. In addition, the current source 70 may control the magnitude of the drive current I _h based on information stored in the storage unit 60. In this case, the storage unit 60 may store information on the relationship between the resistance value R _h of the Hall element 11 and the drive current I _h .

[Example 8]
FIG. 9 shows an example of the configuration of the current sensor 100 according to the eighth embodiment. The control circuit 20 includes a Hall resistance measurement circuit 41, a temperature compensation circuit 42, and a signal processing circuit 50. The current sensor 100 of this example drives the Hall element 11 at a constant voltage. The current sensor 100 includes an ammeter A.

The control circuit 20 causes the constant voltage drive the Hall element 11 by the driving voltage V _h. Ammeter A detects the current I _h flowing through the Hall element 11 in response to the drive voltage V _h. The control circuit 20 controls the drive voltage applied to the Hall element 11 by the control circuit 20 based on the potential difference V _h between both ends in the drive direction of the Hall element 11. That is, when the Hall element 11 is a constant voltage drive, the potential difference _{V h} is a driving voltage _{V h.}

Hall resistance measuring circuit 41 based on the current _{I h} and the voltage _{V h,} measuring the resistance of the Hall element 11. Hall resistance measuring circuit 41 of this example, in accordance with the driving direction of the current I _h and the driving voltage V _h of the Hall element 11, to generate a resistance measurement signal S _r.

The temperature compensation circuit 42 adjusts the drive voltage V _h of the Hall element 11 according to the resistance measurement signal _Sr. As a result, the temperature compensation circuit 42 cancels the temperature characteristics of the current sensor 100.

  Note that the method of driving the Hall element 11 at a constant voltage can be similarly applied to the second and fourth embodiments in which the gain of the signal processing circuit 50 is adjusted.

  FIG. 10 shows an example of the configuration of the ammeter A of the current sensor 100 according to the eighth embodiment. The figure shows details of the Hall element 11, Hall resistance measurement circuit 41, temperature compensation circuit 42, and ammeter A.

The temperature compensation circuit 42 includes operational amplifiers OP1 and OP2 and transistors Tr1 and Tr2. Both ends of the Hall element 11 are set to potentials VH and VL by the operational amplifier OP1 and the operational amplifier OP2, respectively. Therefore, the voltage V _h = VH−VL is applied to both ends in the driving direction of the Hall element 11.

The transistor Tr3 is connected in parallel with the transistor Tr2 to form a current mirror. Thus, the transistor Tr3, in response to the current _{I h} flowing through the transistor Tr2, a current flows _{I h.} A current I _h is input to the Hall resistance measurement circuit 41. That is, the circuit configuration of this example functions as an ammeter A that inputs the current _Ih to the Hall resistance measurement circuit 41. Note that the circuit configuration of this example is an example of a circuit configuration including the ammeter A, and the ammeter A may be realized by other configurations.

[Example 9]
FIG. 11 illustrates an example of the configuration of the current sensor 100 according to the ninth embodiment. The control circuit 20 of this example includes a Hall resistance measurement circuit 41, a temperature compensation circuit 42, a signal processing circuit 50, and a storage unit 60. The current sensor 100 drives the Hall element 11 with a constant current. The Hall resistance measurement circuit 41 of this example may operate in the same manner as the Hall resistance measurement circuit 41 according to other embodiments.

Storage unit 60 stores in advance information about the gain of the signal processing circuit 50 corresponding to the resistance value R _h of the Hall element 11. The storage unit 60, a relation between the gain of the resistance value R _h and a signal processing circuit 50 of the Hall element 11 may store those calculated during shipment test process for each individual.

The temperature compensation circuit 42 adjusts the gain that the signal processing circuit 50 gives to the output from the Hall element 11 based on the resistance measurement signal _Sr. Temperature compensation circuit 42 of this example, based on the stored information to the resistance measuring signal S _r and a storage unit 60, generates the gain adjustment signal S _g. The temperature compensation circuit 42 outputs the generated gain adjustment signal _Sg to the signal processing circuit 50. Thereby, the temperature compensation circuit 42 adjusts the gain of the signal processing circuit 50. The current sensor 100 cancels the temperature characteristic of the Hall element 11 by adjusting the gain of the signal processing circuit 50.

[Example 10]
FIG. 12 illustrates an example of the configuration of the current sensor 100 according to the tenth embodiment. The control circuit 20 includes a Hall resistance measurement circuit 41, a temperature compensation circuit 42, a signal processing circuit 50, and a storage unit 60. The Hall resistance measurement circuit 41 includes an A / D conversion circuit 43 and a digital signal processing circuit 44.

The A / D conversion circuit 43 performs A / D conversion on the values of the voltage V _h and the current I _h , respectively. The A / D conversion circuit 43 outputs the result of AD conversion to the digital signal processing circuit 44.

Digital signal processing circuit 44, by operation in accordance with the digital signal outputted from the A / D converter circuit 43, to generate a resistance measurement signal S _r. More specifically, the digital signal processing circuit 44 performs a numerical calculation of R _h = V _h / I _h , and uses the digital value corresponding to the resistance value R _h of the Hall element 11 as the resistance measurement signal S _r, as a temperature compensation circuit. Output to 42.

  The current sensor 100 of this example may be implemented in combination with other examples according to the present specification. For example, the current sensor 100 of this example can be similarly applied to the second and fourth embodiments that adjust the gain of the signal processing circuit 50.

[Example 11]
FIG. 13 shows an example of the configuration of the current sensor 100 according to the eleventh embodiment. The temperature compensation circuit 42 of this example includes a resistance temperature conversion circuit 47 and a drive current generation circuit 48. The storage unit 60 includes a conversion table memory 61.

  The conversion table memory 61 stores a conversion table for converting input data. The conversion table memory 61 of this example includes a plurality of conversion table memories 61 a and 61 b corresponding to the resistance temperature conversion circuit 47 and the drive current generation circuit 48.

The conversion table memory 61a stores information indicating the correspondence between the resistance measurement signal _Sr and the temperature of the Hall element 11. The conversion table memory 61a of the present example stores a conversion table indicating a predetermined correspondence relationship between the resistance measurement signal _Sr and the temperature of the Hall element 11. However, the conversion table memory 61a may store an optimum conversion table for each individual current sensor 100 in the shipping test process. Thereby, the individual difference of the current sensor 100 is eliminated.

  The conversion table memory 61 b stores a conversion table indicating the correspondence between the temperature estimated by the resistance temperature conversion circuit 47 and the sensitivity of the Hall element 11. The conversion table memory 61b of the present example stores a conversion table indicating a predetermined correspondence relationship between the estimated temperature and the element sensitivity. However, the conversion table memory 61b may store an optimal conversion table for each individual current sensor 100 in the shipping test process. Thereby, the individual difference of the current sensor 100 is eliminated.

The resistance temperature conversion circuit 47 converts the resistance value _Rh of the Hall element 11 corresponding to the resistance measurement signal _Sr into the temperature of the corresponding Hall element 11. The resistance temperature conversion circuit 47 of this example receives a resistance measurement signal _Sr as a digital signal. The resistance temperature conversion circuit 47 reads the information stored in the conversion table memory 61 a and converts the resistance measurement signal _Sr into the temperature of the Hall element 11.

The drive current generation circuit 48 predicts the sensitivity of the Hall element 11 at the current temperature based on the input temperature information of the Hall element 11. The driving current generating circuit 48, based on the predicted sensitivity, adjusting the drive current I _h so that the output of the current sensor 100 is constant for each temperature.

Current sensor 100 of the present embodiment, by using the digital signal, adjusting the drive current I _h. The current sensor 100 of this example can be similarly applied to the second and fourth embodiments that adjust the gain of the signal processing circuit 50.

[Example 12]
FIG. 14 illustrates an example of the configuration of the current sensor 100 according to the twelfth embodiment. The control circuit 20 of this example includes a Hall resistance measurement circuit 41, a temperature compensation circuit 42, a signal processing circuit 50, and a storage unit 60. The Hall resistance measurement circuit 41 includes a V / I conversion circuit 45 and a translinear circuit 46. The translinear circuit 46 is an example of an arithmetic circuit.

The V / I conversion circuit 45 converts the voltage V _h at both ends in the driving direction of the Hall element 11 into a current I _vh using the first resistance element R1. When the Hall element 11 is driven at a constant current, the V / I conversion circuit 45 of this example converts the voltage V _h at both ends in the drive direction of the Hall element 11 into a current I _vh . Also, V / I converter circuit 45, in the case of a constant voltage driving the Hall element 11, and converts the driving voltage _{V h} of the Hall element 11 to the current _{I vh.} V / I converter circuit 45 is a conversion factor _{R 1} a voltage _{V h,} is converted into a current _{I vh.} That is, I _vh = V _h / R ₁ Conversion factor R ₁ is the resistance value corresponding to the first resistor element R1.

The translinear circuit 46 outputs a calculation result based on the current I _vh , the reference current I _ref , and the current I _h in the driving direction of the Hall element 11. When the Hall element 11 is driven at a constant current, the translinear circuit 46 is based on the current I _vh , the reference current I _ref , and the drive current I _h of the Hall element 11, and I _h · I _ref / I _vh or I An operation result using the value of _vh · I _ref / I _h is output.

Here, the reference current I _ref is generated based on a resistance corresponding to the second resistance element R2 and a predetermined reference voltage V _ref . That is, I _ref = V _ref / R ₂ holds. Resistance R ₂ is the resistance value corresponding to the second resistor element R2. In addition, the reference voltage V _ref is generally generated using a band gap circuit having a constant value with respect to temperature. In one example, in the case of the current sensor 100 that requires an output proportional to the power supply voltage, it is preferable to use a voltage obtained by dividing the power supply voltage as the reference voltage _Vref .

The translinear circuit 46 of this example receives the current I _vh , the drive current I _h , and the reference current I _ref and calculates I _vh · I _ref / I _h . For example, the output current I _trans of the translinear circuit 46 is expressed by the following equation.
I _trans = I _vh · I _ref / I _h = (V _h / I _h ) · (I _ref / R ₁ ) = R _h · (I _ref / R ₁ )
Therefore, the output current I _trans is a current amount including information on the resistance value R _h of the Hall element 11.

The temperature compensation circuit 42 estimates the temperature of the Hall element 11 based on the input information on the resistance value _Rh of the Hall element 11. That is, the temperature compensation circuit 42 estimates the temperature of the Hall element 11 from the output current I _trans . In one example, the temperature compensation circuit 42 estimates the temperature of the Hall element 11 based on the information stored in the storage unit 60.

The storage unit 60 stores information for estimating the temperature of the Hall element 11 based on the information on the resistance value R _h of the Hall element 11. For example, the storage unit 60 stores a conversion table between the output current I _trans and the temperature of the Hall element 11. The storage unit 60 may store optimum information for each individual current sensor 100 in the shipping test process. In this case, the individual difference of the current sensor 100 is eliminated.

Further, the translinear circuit 46 may _receive the current I _vh , the drive current I _h , and the reference current I _ref and calculate I _h · I _ref / I _vh .

The output current I _trans of the translinear circuit 46 is expressed by the following equation.
I _trans = I _h · I _ref / I _{vh
= I h · I ref / (} V h / R 1)
= (I _h / V _h ) · I _ref · R ₁
= (1 / R _h ) · I _ref · R ₁
Therefore, the output current I _trans is a current including information on the resistance value R _h of the Hall element 11.

In this case, the internal reference current I _ref becomes I _ref = V _ref / R ₂ from the internal reference voltage V _ref and the resistance value R ₂ . Further, the first resistance element R1 and the second resistance element R2 can be regarded as R ₁ = R ₂ by being composed of the same type of resistance elements. Therefore, the output current I _trans of the translinear circuit 46 is expressed by the following equation.
I _trans = V _ref / R _h

That is, the output current I _trans does not include the resistance values R ₁ and R ₂ . That is, the resistance value _{R 1} and _{R 2} are canceled each other. Since the resistance value changes with temperature, this method is preferable in that the influence can be eliminated. Therefore, the output current I _trans has a current value that depends only on the temperature of the Hall element 11.

[Example 13]
FIG. 15 illustrates an example of a configuration of the current sensor 100 according to the thirteenth embodiment. The control circuit 20 of this example includes a Hall resistance measurement circuit 41, a temperature compensation circuit 42, a signal processing circuit 50, and a storage unit 60. The Hall resistance measurement circuit 41 includes a V / I conversion circuit 45 and a translinear circuit 46.

The V / I conversion circuit 45 converts the input V _h into a current I _vh with a conversion coefficient R ₁ . Here, I _vh = V _h / R ₁ holds.

The translinear circuit 46 is an example of an arithmetic circuit. The translinear circuit 46 receives the current I _vh , the drive current I _h , and the reference current I _ref and calculates I _vh · I _ref / I _h . The output current I _trans of the translinear circuit 46 is expressed by the following equation.
I _trans = I _vh · I _ref / I _h
= (V _h / I _h ) · (I _ref / R ₁ )
= _Rh · (I _ref / R ₁ )
Therefore, the output current I _trans is a current amount including information on the resistance value R _h of the Hall element 11.

The temperature compensation circuit 42 estimates the temperature of the Hall element 11 based on the input information on the resistance value _Rh of the Hall element 11. That is, the temperature compensation circuit 42 estimates the temperature of the Hall element 11 from the output current I _trans . In one example, the temperature compensation circuit 42 estimates the temperature of the Hall element 11 based on the information stored in the storage unit 60. Thus, the temperature compensation circuit 42 generates the gain adjustment signal S _g. The temperature compensation circuit 42 outputs the generated gain adjustment signal _Sg to the signal processing circuit 50.

The storage unit 60 stores information for estimating the temperature of the Hall element 11 based on the information on the resistance value R _h of the Hall element 11. For example, the storage unit 60 stores a conversion table between the output current I _trans and the temperature of the Hall element 11. The storage unit 60 may store optimum information for each individual current sensor 100 in the shipping test process. In this case, the individual difference of the current sensor 100 is eliminated.

  The current sensor 100 of this example adjusts the gain of the signal processing circuit 50 using an analog signal. The current sensor 100 of this example can be similarly applied to the second and fourth embodiments that adjust the gain of the signal processing circuit 50.

  As described above, the current sensors 100 according to Examples 1 to 13 directly cancel the temperature characteristics of the current sensor 100 by directly measuring the temperature of the magnetic sensor 10. The current sensors 100 according to the first to thirteenth embodiments may be implemented in combination as necessary.

[Example 14]
FIG. 16 illustrates an example of the configuration of the current sensor 100 according to the fourteenth embodiment. The control circuit 20 of this example includes an adjustment circuit 40, a signal processing circuit 50, and a storage unit 60.

Adjusting circuit 40 based on the detection signal S _d, to generate an offset adjustment signal S _off for adjusting the offset of the signal processing circuit 50. Thereby, the adjustment circuit 40 controls the offset that the signal processing circuit 50 gives to the output from the Hall element 11. The adjustment circuit 40 may control the offset that the signal processing circuit 50 gives to the output from the Hall element 11 based on the output from the arithmetic circuit disclosed in another embodiment. The adjustment circuit 40 adjusts the offset of the signal processing circuit 50 that amplifies the output of the magnetic sensor 10. Thereby, the adjustment circuit 40 sets the offset of the current sensor 100 to zero regardless of the temperature.

  The current sensor 100 of this example adjusts the offset of the signal processing circuit 50 based on the temperature obtained by directly measuring the temperature of the magnetic sensor 10. As a result, the current sensor 100 can zero the offset that the signal processing circuit 50 gives to the output from the Hall element 11 regardless of the temperature.

  Moreover, the current sensor 100 of the present example may be applied to other embodiments of the current sensor 100 according to the present specification. That is, the current sensor 100 according to the present specification may correct the temperature characteristics of the offset of the magnetic sensor 10 by measuring the temperature of the magnetic sensor 10. Further, the current sensor 100 according to the present specification may adjust the temperature characteristic of the offset in addition to adjusting the temperature characteristic of the sensitivity of the magnetic sensor 10. Furthermore, the current sensor 100 according to the present specification may adjust the temperature characteristic of the offset in addition to adjusting the temperature characteristic of the gain of the signal processing circuit 50.

  FIG. 17 shows an example of a specific configuration of the current sensor 100. The current sensor 100 of this example includes a magnetic sensor 10, a control circuit 20, a conductor 30, a first substrate 31, and a package 35.

  The package 35 is formed so as to cover the magnetic sensor 10, the control circuit 20, and the conductor 30 disposed on the first substrate 31. The package 35 is formed of an insulating material such as resin or ceramic.

The conductor 30 is formed close to the magnetic sensor 10. The conductor 30 is provided such that the distance from the control circuit 20 is different from the distance from the magnetic sensor 10. The conductor 30 of this example is formed so as to be closer to the magnetic sensor 10 than the control circuit 20. For example, an interval is provided between the control circuit 20 and the conductor 30 so that sufficient insulation is maintained. On the other hand, the magnetic sensor 10 and conductor 30, the change in magnetic field corresponding to the measured current I _o flowing through the conductor 30 a magnetic sensor 10 is arranged close enough to be detected. The conductor 30 of this example is formed between the magnetic sensor 10 and the control circuit 20 on the first substrate 31. The conductor 30 of this example is formed so as to cross between the magnetic sensor 10 and the control circuit 20 in plan view. In this specification, the plan view refers to a viewpoint in a direction perpendicular to the upper surface of the circuit board.

  Since the magnetic sensor 10 is formed close to the conductor 30, the temperature may increase inside the package 35. Therefore, a temperature difference is generated between the magnetic sensor 10 and the control circuit 20. Note that the current sensor 100 of this example includes a conductor 30 wired between the magnetic sensor 10 and the control circuit 20. That is, the current sensor 100 is arranged in the order of the magnetic sensor 10, the conductor 30, and the control circuit 20. However, the current sensor 100 may be disposed in the order of the conductor 30, the magnetic sensor 10, and the control circuit 20, or may be disposed in the order of the conductor 30, the control circuit 20, and the magnetic sensor 10. That is, the present invention is not limited to this example as long as the temperature difference between the magnetic sensor 10 and the control circuit 20 is caused by the temperature rise of the conductor 30.

  The control circuit 20 is formed on the first substrate 31. The control circuit 20 includes a first resistance element R1 and a second resistance element R2. The first resistance element R1 and the second resistance element R2 are formed on the first substrate 31. When the first resistance element R1 and the second resistance element R2 are formed on the same first substrate 31, the gap between the first resistance element R1 and the second resistance element R2 is greater than when they are formed on different substrates. Temperature differences are less likely to occur. Thereby, it becomes difficult to produce a difference between the resistance value of the first resistance element R1 and the resistance value of the second resistance element R2. Here, it is preferable that the resistance values of the first resistance element R1 and the second resistance element R2 similarly change according to the temperature change of the magnetic sensor 10. By similarly changing the temperature characteristics of the first resistance element R1 and the second resistance element R2, the temperature characteristics of the current sensor 100 can be canceled without being affected by the resistance.

The first resistance element R1 and the second resistance element R2 may be made of the same material. Further, the first resistance element R1 and the second resistance element R2 may have the same resistance value by having the same length, or may have different resistance values by having different lengths. Good. When the first resistance element R1 and the second resistance element R2 have different resistance values, it is preferable that the temperature compensation circuit 42 has information regarding the resistance ratio between the first resistance element R1 and the second resistance element R2. As a result, the temperature compensation circuit 42 can cancel the resistance component from the output current I _trans .

In this case, the current sensor 100 cancels the temperature characteristics of the magnetic sensor 10 without being affected by changes in the temperature characteristics of the first resistance element R1 and the second resistance element R2. Therefore, the current sensor 100 of this example can reduce the temperature characteristics of the magnetic sensor 10 with high accuracy. In particular, when the current sensor 100 is a built-in conductor 30 which flows the current to be measured I _o, the control circuit 20 is easily affected by heat of the conductor 30. Therefore, since the first resistance element R1 and the second resistance element R2 are substantially the same, the effect of canceling the temperature characteristics of the magnetic sensor 10 is high.

  Further, the current sensor 100 may have a power ratio ratio in which the sensitivity changes according to the power supply voltage, or may have a power supply non-ratio characteristic in which the sensitivity does not depend on the power supply voltage. The current sensor 100 may be switchable between power ratio ratio and non-ratio, and as an example, the current sensor 100 may be a register that can write / read the power ratio ratio and non-ratio characteristics from the outside, or You may have a selection pin etc. which can change a setting.

  As mentioned above, although this invention was demonstrated using embodiment, the technical scope of this invention is not limited to the range as described in the said embodiment. It will be apparent to those skilled in the art that various modifications or improvements can be added to the above-described embodiment. It is apparent from the scope of the claims that the embodiments added with such changes or improvements can be included in the technical scope of the present invention.

  The order of execution of each process such as operations, procedures, steps, and stages in the apparatus, system, program, and method shown in the claims, the description, and the drawings is particularly “before” or “prior to”. It should be noted that the output can be realized in any order unless the output of the previous process is used in the subsequent process. Regarding the operation flow in the claims, the description, and the drawings, even if it is described using “first”, “next”, etc. for convenience, it means that it is essential to carry out in this order. It is not a thing.

DESCRIPTION OF SYMBOLS 10 ... Magnetic sensor, 11 ... Hall element, 20 ... Control circuit, 30 ... Conductor, 31 ... 1st board | substrate, 35 ... Package, 40 ... Adjustment circuit, 41. ..Hall resistance measurement circuit, 42... Temperature compensation circuit, 43... A / D conversion circuit, 44... Digital signal processing circuit, 45. Circuit, 47 ... Resistance temperature conversion circuit, 48 ... Drive current generation circuit, 50 ... Signal processing circuit, 60 ... Storage unit, 61 ... Conversion table memory, 70 ... Current source, DESCRIPTION OF SYMBOLS 100 ... Current sensor, 500 ... Current sensor, 510 ... Hall element, 520 ... Temperature sensor, 530 ... Conductor, 540 ... Adjustment circuit, 550 ... Signal processing circuit

Claims (10)

In a control circuit for controlling a magnetic sensor having a Hall element,
A V / I conversion circuit that converts a potential difference between both ends in the driving direction of the Hall element into a current I _vh using a first resistance element;
Based on the current I _vh , the reference current I _ref , and the current I _h in the driving direction of the Hall element, a calculation result using a value of I _h · I _ref / I _vh or I _vh · I _ref / I _h An arithmetic circuit that outputs
A temperature compensation circuit that compensates for the influence of temperature on the output of the Hall element based on the calculation result, and
The reference current I _ref is generated based on a resistance corresponding to the second resistance element and a reference voltage V _ref that does not depend on temperature. The control circuit according to claim 1, wherein the first resistance element and the second resistance element are configured by the same type of resistance element. The control circuit according to claim 1, wherein the first resistance element and the second resistance element are provided in the control circuit. A current source for supplying a driving current to the Hall element;
The temperature compensation circuit controls a drive current that the current source gives to the Hall element based on an output from the arithmetic circuit.
The control circuit according to any one of claims 1 to 3. A signal processing circuit for amplifying and outputting the output from the Hall element;
The temperature compensation circuit controls a gain and / or an offset that the signal processing circuit gives to an output from the Hall element based on an output from the arithmetic circuit. The control circuit described. The control circuit according to claim 1, wherein the arithmetic circuit includes a translinear circuit. A conductor through which the current to be measured flows;
A hall element that is formed of a compound semiconductor and outputs a signal corresponding to the current to be measured;
A control circuit that compensates for the influence of temperature on the output of the Hall element based on the voltage value or current value detected from the Hall element;
The conductor is formed closer to the Hall element than the control circuit,
The control circuit includes:
A resistance measuring circuit that outputs a Hall element resistance based on a potential difference between both ends in the driving direction of the Hall element and a current value in the driving direction;
The control circuit compensates for the influence of temperature on the output of the Hall element based on the Hall element resistance ,
The resistance measurement circuit includes:
A V / I conversion circuit for converting the driving voltage V _h of the Hall element into a current I _vh when the Hall element is driven at a constant voltage ;
An arithmetic circuit that outputs the Hall element resistance based on the current I _vh , the reference current I _ref , and the current value I _h in the driving direction of the Hall element;
Have
The reference current I _ref is generated based on a resistance corresponding to the resistance element and a reference voltage V _ref that does not depend on temperature .
The Hall element _resistor, a current sensor is calculated using the values of _{I h ·} I ref _/ I _vh or _{I vh · I ref / I h} . The current sensor according to claim 7, further comprising a package that covers the conductor, the Hall element, and the control circuit. A conductor through which the current to be measured flows;
A hall element that is formed of a compound semiconductor and outputs a signal corresponding to the current to be measured;
A control circuit that compensates for the influence of temperature on the output of the Hall element based on the voltage value or current value detected from the Hall element;
With
The conductor is formed closer to the Hall element than the control circuit,
The control circuit includes:
A resistance measuring circuit that outputs a Hall element resistance based on a potential difference between both ends in the driving direction of the Hall element and a current value in the driving direction;
The control circuit compensates for the influence of temperature on the output of the Hall element based on the Hall element resistance,
The resistance measurement circuit includes:
A V / I conversion circuit for converting a potential difference between both ends in the driving direction of the Hall element when the Hall element is driven at a constant current into a current I _vh ;
An arithmetic circuit that outputs the Hall element resistance based on the current I _vh , the reference current I _ref , and the Hall element drive current I _h ;
Have
The reference current I _ref is generated based on a resistance corresponding to the resistance element and a reference voltage V _ref that does not depend on temperature.
The Hall element _{resistance, I h · I ref / I} vh or _I vh _{· I} ref / _{I h} Ru current sensor is calculated using the value of. Further comprising a current source for supplying the driving current I _h to the Hall element,
The control circuit includes a temperature compensation circuit that controls the driving current _Ih that the current source applies to the Hall element based on a potential difference between both ends in the driving direction of the Hall element.
The current sensor according to claim 9.

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