Constant-current power supply circuit with temperature compensation and load device

Abstract

The utility model discloses a constant current power supply circuit with temperature compensation and a load device, the constant current power supply circuit comprises a three-terminal voltage-regulator tube, a negative temperature coefficient thermistor and at least one shunt resistor, the shunt resistor is connected in parallel with the negative temperature coefficient thermistor, the cathode of the three-terminal voltage-regulator tube is connected with a direct current power supply, and the anode of the three-terminal voltage-regulator tube is connected with the negative temperature coefficient thermistor. An anode of the three-terminal voltage-regulator tube is connected with a first terminal of the negative temperature coefficient thermistor, a reference terminal of the three-terminal voltage-regulator tube is connected with a second terminal of the negative temperature coefficient thermistor, and the anode of the three-terminal voltage-regulator tube is connected with a power supply terminal of a load. According to the utility model, the constant current power supply circuit is formed based on the three-terminal voltage-regulator tube and the negative temperature coefficient thermistor, so that the precision and the stability of a product are improved while the temperature compensation is enhanced.

Description

Technical Field

[0001] The utility model belongs to the technical field of power supply, and particularly relates to a constant current power supply circuit with temperature compensation and a load device. Background Art

[0002] When an electronic load such as a Hall device is working, due to the influence of factors such as the magnetic core, its temperature characteristics are sensitive. The constant current drive of the Hall device itself is more stable than the constant voltage drive in terms of temperature characteristics, so the constant current drive method is mostly adopted. However, since only the constant current source drive method is currently used and no special compensation for the temperature influence is made, the output of the product fails to meet the expected requirements. Moreover, the constant current source circuit composed of triodes has slight differences due to different batches of triodes. Since the current source relies on the Vbe of the triodes, the consistency of the circuit values of different batches cannot be ensured. Content of the Utility Model

[0003] In order to solve the above problems existing in the prior art, the present application provides a constant current power supply circuit with temperature compensation and a load device, in which the negative temperature coefficient thermistor and the diode in the constant current power supply circuit enhance the temperature compensation and improve the stability of the circuit.

[0004] The utility model adopts the following technical solutions:

[0005] On the one hand, the utility model proposes a constant current power supply circuit with temperature compensation, including: a three-terminal voltage regulator, a negative temperature coefficient thermistor, and at least one shunt resistor. The shunt resistor is connected in parallel with the negative temperature coefficient thermistor. The cathode of the three-terminal voltage regulator is connected to a DC power supply, the anode of the three-terminal voltage regulator is connected to the first end of the negative temperature coefficient thermistor, the reference terminal of the three-terminal voltage regulator is connected to the second end of the negative temperature coefficient thermistor, and the anode of the three-terminal voltage regulator is connected to the power supply terminal of the load. Adding a negative temperature coefficient thermistor to the constant current power supply circuit strengthens the temperature compensation of the constant current source power supply.

[0006] Preferably, the constant current power supply circuit further includes a diode, and the diode is connected in parallel with the negative temperature coefficient thermistor. Adding a diode in front of the input end of the negative temperature coefficient thermistor plays a role in partial temperature compensation.

[0007] Further preferably, the cathode of the three-terminal voltage regulator is connected to the positive terminal of the DC power supply. The anode of the three-terminal voltage regulator is connected to the cathode of the diode, the first terminal of the negative temperature coefficient thermistor, and the power supply terminal of the load. The reference terminal of the three-terminal voltage regulator is connected to the second terminal of the negative temperature coefficient thermistor through the first resistor and the third resistor. The anode of the diode is connected to one end of the first resistor and the third resistor through the second resistor. By connecting resistors in parallel to achieve current shunting and reduce the power of a single resistor, the lifespan of electronic components is guaranteed and the reliability of the circuit is improved. At the same time, it prevents the negative temperature coefficient thermistor from being overly affected by temperature and causing overcompensation.

[0008] Preferably, the model of the three-terminal voltage regulator is one of TL431, CJ431, and AZ431.

[0009] Preferably, it further includes a voltage stabilizing circuit and a variable resistor zero-point adjustment circuit connected to each other. The output terminal of the load is connected to the variable resistor zero-point adjustment circuit. The voltage stabilizing circuit is used to output a regulated power supply, and the variable resistor zero-point adjustment circuit is used for zero-point compensation.

[0010] On the other hand, the present invention proposes a load device, including a load and the constant current power supply circuit described above.

[0011] Preferably, the load includes a first load and a second load. The power supply terminals of the first load and the second load are connected to each other, and the output terminals of the first load and the second load are connected to each other.

[0012] Further preferably, the load includes a Hall current sensor, and the first load and the second load include Hall elements. By setting two interconnected loads, for products with a large current and a large magnetic core through-hole, the two Hall elements can adjust each other to reduce the position error of the current-carrying rod flowing through the Hall sensor, thereby improving the accuracy of the measured current.

[0013] Preferably, the load further includes a differential amplifier circuit. The input terminals of the differential amplifier circuit are connected to the output terminals of the first load and the second load, and the output terminal of the differential amplifier circuit outputs externally.

[0014] Further preferably, the load further includes a variable resistor amplitude adjustment circuit, and the variable resistor amplitude adjustment circuit is connected to the differential amplifier circuit. The variable resistor amplitude adjustment circuit is used for amplitude adjustment.

[0015] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0016] (1) The constant-current power supply circuit of the present utility model includes a three-terminal voltage regulator diode and a negative temperature coefficient thermistor, without the need for redundant semiconductor devices such as triodes, reducing costs and eliminating the variable Vbe, thereby improving the accuracy and stability of the product;

[0017] (2) The temperature compensation of the constant-current power supply circuit of the present utility model is achieved through a diode and a negative temperature coefficient thermistor, enhancing the temperature compensation effect and improving the consistency and stability of the output over the full temperature range;

[0018] (3) The variable resistor zero-point adjustment circuit and the variable resistor amplitude adjustment circuit of the present utility model both include two or more series / parallel resistors, and each resistor is connected or left vacant through a pad to achieve multi-level adjustment and adapt to different specifications of loads;

[0019] (4) The voltage stabilization circuit of the present utility model can output a stabilized power supply to the variable resistor zero-point adjustment circuit to ensure the stable operation of the circuit and prevent components from being burned out. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The accompanying drawings are included to provide a further understanding of the embodiments and are incorporated into and constitute a part of this specification. The drawings illustrate the embodiments and, together with the description, are used to explain the principles of the present utility model. Other embodiments and many of the intended advantages of the embodiments will be readily apparent, as they become better understood by reference to the following detailed description. By reading the detailed description of the non-limiting embodiments with reference to the following drawings, other features, objects, and advantages of the present application will become more apparent:

[0021] Figure 1 is a schematic circuit diagram of a constant-current power supply circuit with temperature compensation according to a specific embodiment of the present utility model;

[0022] Figure 2 is a schematic circuit diagram of a constant-current power supply circuit with temperature compensation according to a specific embodiment of the present utility model;

[0023] Figure 3 is a schematic circuit diagram of a constant-current power supply circuit with temperature compensation according to a specific embodiment of the present utility model;

[0024] Figure 4 is a block diagram of a constant-current power supply circuit with temperature compensation according to a specific embodiment of the present utility model;

[0025] Figure 5 is a schematic circuit diagram of a constant-current power supply circuit with temperature compensation according to a specific embodiment of the present utility model;

[0026] Figure 6 is a block diagram of a load device according to a specific embodiment of the present utility model;

[0027] Figure 7 It is a schematic circuit diagram of a load device according to a specific embodiment of the present invention. Detailed implementation manners

[0028] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts shall fall within the protection scope of the present invention.

[0029] In the description of the present invention, it should be noted that the terms "including", "comprising" or any other variant thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements not only includes those elements, but also includes other elements not expressly listed, or elements inherent to such process, method, article or device. The terms "first" and "second" are only used for descriptive purposes and cannot be construed as indicating or implying relative importance or implicitly indicating the quantity of the indicated technical features.

[0030] In the description of the present invention, it should be noted that unless otherwise clearly defined and limited, the terms "installed", "provided with", "sheathed / connected", "connected", etc. should be understood in a broad sense. For example, "connected" can be a fixed connection, a detachable connection, or an integral connection, can be a mechanical connection, can be an electrical connection, can be directly connected, or can be indirectly connected through an intermediate medium, and can be the internal communication of two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood in specific situations.

[0031] Embodiment 1:

[0032] Figure 1 A schematic circuit diagram of a constant current power supply circuit with temperature compensation according to a specific embodiment of the present invention is shown. As Figure 1 shown, a constant current power supply circuit with temperature compensation includes a three-terminal voltage regulator N1, a negative temperature coefficient thermistor NTC1, and a second resistor R2. The second resistor R2 serves as a shunt resistor. The second resistor R2 is connected in parallel with the negative temperature coefficient thermistor NTC1. The cathode of the three-terminal voltage regulator N1 is connected to a DC power supply. The anode of the three-terminal voltage regulator N1 is connected to the first end of the negative temperature coefficient thermistor NTC1. The reference terminal of the three-terminal voltage regulator N1 is connected to the second end of the negative temperature coefficient thermistor NTC1. The anode of the three-terminal voltage regulator N1 is connected to the power supply terminal of the load 20.

[0033] Taking the load 20 as a Hall current sensor as an example, the specific compensation principle is described as follows. When the temperature rises, due to the characteristics of the magnetic core, the magnetic field intensity input to the Hall becomes weaker, resulting in a smaller output of the Hall element. As the temperature rises, the resistance value of the negative temperature coefficient thermistor NTC1 decreases. According to Ohm's law, the voltage across the negative temperature coefficient thermistor NTC1 increases, the current passing through the Hall element becomes larger, and the output of the Hall element becomes larger, thus achieving compensation. Connecting a resistor R2 in parallel with the negative temperature coefficient thermistor can shunt the current to reduce the power of a single resistor, thereby ensuring the lifespan of electronic components and improving the reliability of the circuit.

[0034] The selected model of the three-terminal voltage regulator is one of TL431, CJ431, and AZ431.

[0035] In this embodiment, taking the load 20 as a Hall current sensor as an example, optionally, the first load H1 and the second load H2 connected to each other are set. For products with a large current and a large magnetic core through-hole, the two Hall elements can adjust each other to reduce the position error of the current-carrying rod passing through the Hall sensor, thereby improving the accuracy of the measured current. The load 20 includes the first load H1 and the second load H2. The power supply terminals of the first load H1 and the second load H2 are connected, and the output terminals of the first load H1 and the second load H2 are connected. The first load H1 and the second load H2 refer to Hall elements, and the number of loads can be adjusted according to actual needs. For example, setting one load H1 can also achieve the effect of the present invention.

[0036] Embodiment 2:

[0037] Figure 2 The circuit schematic diagram of a constant current power supply circuit with temperature compensation according to a specific embodiment of the present invention is shown, as Figure 2 shown, a constant current power supply circuit with temperature compensation includes a three-terminal voltage regulator N1, a negative temperature coefficient thermistor NTC1, a second resistor R2, and a diode D1. The second resistor R2 serves as a shunt resistor, and the second resistor R2 is connected in parallel with the negative temperature coefficient thermistor NTC1. The cathode of the three-terminal voltage regulator N1 is connected to a DC power supply, the anode of the three-terminal voltage regulator N1 is connected to the first end of the negative temperature coefficient thermistor NTC1, the cathode of the diode D1, and the power supply terminal of the load. The reference terminal of the three-terminal voltage regulator N1 is connected to the second end of the negative temperature coefficient thermistor NTC1, and the anode of the diode D1 is connected to the reference terminal of the three-terminal voltage regulator and the second end of the negative temperature coefficient thermistor NTC1 through the second resistor R2.

[0038] Taking the load as a Hall current sensor as an example, the specific compensation principle is described as follows. A diode D1 is added in front of the input end of the negative temperature coefficient thermistor NTC1 to play a role in partial temperature compensation. When the temperature rises, due to the characteristics of the magnetic core, the magnetic field strength input to the Hall becomes weaker, resulting in a smaller output of the Hall element. As the temperature rises, the voltage drop across the diode decreases, and the resistance of the negative temperature coefficient thermistor NTC1 also decreases due to the increase in temperature. According to Ohm's law, the voltage across the negative temperature coefficient thermistor NTC1 increases, the current passing through the Hall element becomes larger, and the output of the Hall element becomes larger, thus achieving compensation. Connecting a resistor R2 in parallel with the negative temperature coefficient thermistor NTC1 can shunt the current to reduce the power of a single resistor, thereby ensuring the lifespan of electronic components and improving the reliability of the circuit.

[0039] The type of the selected three-terminal voltage regulator is one of TL431, CJ431, and AZ431.

[0040] In this embodiment, taking the load 20 as a Hall current sensor as an example, optionally, a first load H1 and a second load H2 connected to each other are set. For products with a large current and a large magnetic core through-hole, the two Hall elements can adjust each other to reduce the position error of the current-carrying rod passing through the Hall sensor, thereby improving the accuracy of the measured current. The load 20 includes a first load H1 and a second load H2. The power supply terminals of the first load H1 and the second load H2 are connected, and the output terminals of the first load H1 and the second load H2 are connected. The first load H1 and the second load H2 refer to Hall elements, and the number of loads can be adjusted according to actual needs. For example, setting one load H1 can also achieve the effect of the present invention.

[0041] Embodiment 3:

[0042] Figure 3 The circuit schematic diagram of a constant current power supply circuit with temperature compensation according to a specific embodiment of the present invention is shown, as Figure 3 shown, a constant current power supply circuit with temperature compensation includes a three-terminal voltage regulator N1, a negative temperature coefficient thermistor NTC1, a diode D1, a first resistor R1, a second resistor R2, and a third resistor R3. The cathode of the three-terminal voltage regulator N1 is connected to the positive terminal of the DC power supply. The anode of the three-terminal voltage regulator N1 is connected to the cathode of the diode D1, the first end of the negative temperature coefficient thermistor NTC1, and the power supply terminal of the load. The reference terminal of the three-terminal voltage regulator N1 is connected to the second end of the negative temperature coefficient thermistor NTC1 through the first resistor R1 and the third resistor R3. The anode of the diode D1 is connected to one end of the first resistor R1 and the third resistor R3 through the second resistor R2.

[0043] Taking the load 20 as a Hall current sensor as an example, the specific compensation principle is described as follows. A diode D1 is added in front of the input end of the negative temperature coefficient thermistor NTC1 to play a role in partial temperature compensation. When the temperature rises, due to the characteristics of the magnetic core, the magnetic field intensity input to the Hall becomes weaker, resulting in a smaller output of the Hall element. As the temperature rises, the voltage drop across the diode D1 decreases, and the resistance of the negative temperature coefficient thermistor NTC1 also decreases due to the temperature rise. According to Ohm's law, the voltage across the negative temperature coefficient thermistor NTC1 increases, the current passing through the Hall element becomes larger, and the output of the Hall element becomes larger, thus achieving compensation. Among them, the first resistor R1 and the second resistor R2 are in parallel with the negative temperature coefficient thermistor, which can shunt and reduce the power of a single resistor. The resistor in parallel with the diode D1 can protect the diode D1, thereby ensuring the lifespan of the electronic components and improving the reliability of the circuit. This embodiment provides a combination of resistors to meet the resistance value required for the constant current source power supply of the Hall component and can also prevent the thermistor from being overly affected by temperature to cause overcompensation.

[0044] The selected model of the said three-terminal voltage regulator is one of TL431, CJ431 and AZ431.

[0045] In this embodiment, taking the load 20 as a Hall current sensor as an example, optionally, a first load H1 and a second load H2 connected to each other are set. For products with larger current and magnetic core through holes, the two Hall elements can adjust each other to reduce the position error of the current-carrying rod flowing through the Hall sensor, thereby improving the accuracy of the measured current. The load 20 includes a first load H1 and a second load H2. The power supply terminals of the first load H1 and the second load H2 are connected, and the output terminals of the first load H1 and the second load H2 are connected. Here, the first load H1 and the second load H2 refer to Hall elements, and the number of loads can be adjusted according to actual needs. For example, setting a single load H1 can also achieve the effect of the present utility model.

[0046] Embodiment 4:

[0047] Figure 4 The structural block diagram of the constant current power supply circuit with temperature compensation according to a specific embodiment of the present utility model is shown, as Figure 4As shown, a constant current power supply circuit with temperature compensation includes a three-terminal voltage regulator N1, a negative temperature coefficient thermistor NTC1, a second resistor R2, a load 20, a variable resistor zero adjustment circuit 30, a voltage stabilization circuit 40, and a DC power supply 10 which are connected. The second resistor R2 is in parallel with the negative temperature coefficient thermistor NTC1. The cathode of the three-terminal voltage regulator N1 is connected to the DC power supply 10. The anode of the three-terminal voltage regulator N1 is connected to the first end of the negative temperature coefficient thermistor NTC1. The reference terminal of the three-terminal voltage regulator N1 is connected to the second end of the negative temperature coefficient thermistor NTC1. The anode of the three-terminal voltage regulator N1 is connected to the power supply terminal of the load 20. The voltage stabilization circuit 40 is connected to the DC power supply 10 to provide a regulated power supply for the circuit. The variable resistor adjustment circuit 30 is connected to the voltage stabilization circuit 40 and the load 20 for zero compensation. The constant current power supply circuit can make special compensation for the influence of temperature.

[0048] It should be noted that Figure 4 The second resistor R2 shown in

[0049] is taken as an example of a shunt resistor, and it is not limited to only this combination of parallel resistors. Figure 5 Next, with reference to the circuit schematic diagram of the constant current power supply circuit with temperature compensation according to a specific embodiment of the present invention shown in

[0050] The constant current power supply circuit includes a three-terminal voltage regulator N1, a negative temperature coefficient thermistor NTC1, and at least one resistor in parallel with the negative temperature coefficient thermistor NTC1. The cathode of the three-terminal voltage regulator N1 is connected to the DC power supply 10. The anode of the three-terminal voltage regulator N1 is connected to the first end of the negative temperature coefficient thermistor NTC1. The reference terminal of the three-terminal voltage regulator N1 is connected to the second end of the negative temperature coefficient thermistor NTC1. The anode of the three-terminal voltage regulator N1 is connected to the power supply terminal of the load 20. The variable resistor zero adjustment circuit 30 is respectively connected to the output terminals of the voltage stabilization circuit 40 and the load 20.

[0051] Optionally, the constant current power supply further includes a diode D1 and at least one shunt resistor in parallel with the diode D1. The diode D1 is used for partial temperature compensation. The cathode of the diode D1 is connected to the anode of the three-terminal voltage regulator N1 and the first end of the negative temperature coefficient thermistor NTC1. The anode of the diode D1 is connected to the reference terminal of the three-terminal voltage regulator N1 and the second end of the negative temperature coefficient thermistor NTC1.

[0052] It should be noted that at least one resistor is connected in parallel to the negative temperature coefficient thermistor NTC1 to achieve shunt current and reduce the power of a single resistor, thereby ensuring the lifespan of electronic components and improving the reliability of the circuit. At least one resistor is also connected in parallel to the diode D1 to achieve partial temperature compensation. Therefore, in specific embodiments, the resistors can be arbitrarily combined according to the requirements of the load 20 or the constant current source power supply, and some resistors are connected in parallel in different combinations.

[0053] For the sake of convenience in explanation, this embodiment takes a parallel resistor combination provided according to the constant current source power supply requirements adapted to the Hall component as an example for illustration. The resistor combination in this embodiment can prevent the negative temperature coefficient thermistor NTC1 from being overly affected by temperature and causing overcompensation. For example, the cathode of the three-terminal voltage regulator N1 is connected to the positive terminal of the DC power supply 10. The anode of the three-terminal voltage regulator N1 is connected to the cathode of the diode D1, the first terminal of the negative temperature coefficient thermistor NTC1, and the power supply terminal of the load 20. The reference terminal of the three-terminal voltage regulator N1 is connected to the second terminal of the negative temperature coefficient thermistor NTC1 through the first resistor R1 and the third resistor R3. The anode of the diode D1 is connected to one end of the first resistor R1 and the third resistor R3 through the second resistor R2.

[0054] The constant current power supply circuit of the present utility model includes a three-terminal voltage regulator N1 and a negative temperature coefficient thermistor NTC1. Temperature compensation is achieved through the negative temperature coefficient thermistor NTC1 and the diode D1. While enhancing temperature compensation, it saves components, reduces costs, and improves product stability. The following takes the load 20 as a Hall current sensor as an example to illustrate the specific compensation principle. A diode D1 is added in front of the input end of the negative temperature coefficient thermistor NTC1 to achieve partial temperature compensation. When the temperature rises, due to the characteristics of the magnetic core, the magnetic field intensity input to the Hall becomes weaker, resulting in a smaller output of the Hall element. As the temperature rises, the voltage drop across the diode decreases, and the resistance of the negative temperature coefficient thermistor NTC1 also decreases due to the increase in temperature. According to Ohm's law, the voltage across the negative temperature coefficient thermistor NTC1 increases, the current passing through the Hall element increases, and the output of the Hall element increases, thereby achieving compensation.

[0055] Optionally, the voltage stabilizing circuit 40 is used to output a regulated power supply, and includes a first voltage stabilizing diode Q1, a second voltage stabilizing diode Q2, a fourth resistor R4, and a fifth resistor R5. The anode of the first voltage stabilizing diode Q1 is connected to the cathode of the second voltage stabilizing diode Q2. The cathode of the first voltage stabilizing diode Q1 is connected to the positive terminal of the DC power supply 10 through the fourth resistor R4. The anode of the second voltage stabilizing diode Q2 is connected to the negative terminal of the DC power supply 10 through the fifth resistor R5. The output terminal of the voltage stabilizing circuit 40 is connected to the variable resistor zero adjustment circuit 30.

[0056] In this embodiment, the shown voltage stabilizing diodes include two in series, namely the first voltage stabilizing diode Q1 and the second voltage stabilizing diode Q2. The voltage stabilizing circuit 40 can output a regulated power supply to the variable resistor zero point adjustment circuit 30 to ensure the stable operation of the circuit and prevent the components from being burned out.

[0057] It should be noted that the variable resistor zero point adjustment circuit 30 includes two or more resistors, and the two or more resistors can be combined arbitrarily, such as being connected in series with each other, being connected in parallel with each other, or some resistors being connected in series and some resistors being connected in parallel, as long as it can be realized that when one or more resistors are connected or left vacant through the pads, the total resistance value changes. The specific setting method of the resistors is not limited in the present utility model.

[0058] For the convenience of description, this embodiment takes the variable resistor zero point adjustment circuit 30 including four resistors as an example for illustration. Optionally, the variable resistor zero point adjustment circuit 30 is used for zero point compensation and includes a sixth resistor R6, a seventh resistor R7, an eighth resistor R8, and a ninth resistor R9. One end of the circuit after the sixth resistor R6 and the seventh resistor R7 are connected in parallel is connected in series with one end of the circuit after the eighth resistor R8 and the ninth resistor R9 are connected in parallel. The connection point of the circuit after the sixth resistor R6 and the seventh resistor R7 are connected in parallel and the circuit after the eighth resistor R8 and the ninth resistor R9 are connected in parallel is connected to the output end of the load. The other end of the circuit after the sixth resistor R6 and the seventh resistor R7 are connected in parallel is connected to the voltage stabilizing circuit 40, and the other end of the circuit after the eighth resistor R8 and the ninth resistor R9 are connected in parallel is connected to the voltage stabilizing circuit 40; the sixth resistor R6, the seventh resistor R7, the eighth resistor R8, and the ninth resistor R9 are respectively connected or left vacant through the pads.

[0059] The electronic load 20, such as the magnetic load 20, is affected by temperature, magnetic field, etc., and its zero point will shift, which will further lead to a decrease in the measurement accuracy. Therefore, zero point compensation is required.

[0060] In this embodiment, taking the load 20 as an open-loop Hall current sensor as an example, optionally, two connected loads are set. For products with a large current and a large magnetic core through hole, the two Hall elements can adjust each other to reduce the position error of the current-carrying rod flowing through the Hall sensor, thereby improving the accuracy of the measured current. The load 20 includes a first load H1 and a second load H2. The power supply terminals of the first load H1 and the second load H2 are connected, and the output terminals of the first load H1 and the second load H2 are connected. The first load H1 and the second load H2 refer to Hall elements, and the number of loads can be adjusted according to actual needs. For example, setting one load H1 can also achieve the effect of the present utility model.

[0061] In a specific embodiment, the constant-current power supply circuit includes a three-terminal voltage regulator N1, a diode D1, a negative temperature coefficient thermistor NTC1, a first resistor R1, a second resistor R2, and a third resistor R3; the load 20 includes a first load H1 and a second load H2. The power supply terminals of the first load H1 and the second load H2 are connected, and the output terminals of the first load H1 and the second load H2 are connected. The selected model of the three-terminal voltage regulator is one of TL431, CJ431, and AZ431.

[0062] In a specific embodiment, the cathode of the three-terminal voltage regulator N1 is connected to the positive terminal of the DC power supply 10. The anode of the three-terminal voltage regulator N1 is connected to the cathode of the diode D1, the first end of the negative temperature coefficient thermistor NTC1, one power supply terminal of the first load H1, and one power supply terminal of the second load H2. The reference terminal of the three-terminal voltage regulator N1 is connected to the second end of the negative temperature coefficient thermistor NTC1 through the first resistor R1 and the third resistor R3. The anode of the diode D1 is connected to one end of the first resistor R1 and the third resistor R3 through the second resistor R2. One output terminal of the second load H2 is grounded, and the other output terminal is connected to the variable resistor zero adjustment circuit 30 through the twenty-second resistor R22 and the twentieth resistor R20. The variable resistor zero adjustment circuit 30 is connected to the voltage stabilization circuit 40.

[0063] In a specific embodiment, the variable resistor zero adjustment circuit 30 includes a sixth resistor R6, a seventh resistor R7, an eighth resistor R8, and a ninth resistor R9; the voltage stabilization circuit 40 includes a first voltage regulator Q1, a second voltage regulator Q2, a fourth resistor R4, and a fifth resistor R5. The anode of the first voltage regulator Q1 is connected to the cathode of the second voltage regulator Q2. One end of the circuit after the sixth resistor R6 and the seventh resistor R7 are connected in parallel is connected in series with one end of the circuit after the eighth resistor R8 and the ninth resistor R9 are connected in parallel. The connection point of the circuit after the sixth resistor R6 and the seventh resistor R7 are connected in parallel and the circuit after the eighth resistor R8 and the ninth resistor R9 are connected in parallel is connected to the output terminal of the second load H2. The other end of the circuit after the sixth resistor R6 and the seventh resistor R7 are connected in parallel is connected to the cathode of the first voltage regulator Q1 and is connected to the positive terminal of the DC power supply 10 through the fourth resistor R4. The other end of the circuit after the eighth resistor R8 and the ninth resistor R9 are connected in parallel is connected to the anode of the second voltage regulator Q2 and is connected to the negative terminal of the DC power supply 10 through the fifth resistor R5.

[0064] Embodiment 5:

[0065] Figure 6 The structural block diagram of the load device according to a specific embodiment of the present invention is shown, as Figure 6As shown, it includes a load and the constant current power supply circuit described above. Specifically, it includes a three-terminal voltage regulator N1, a negative temperature coefficient thermistor NTC1, a second resistor R2, a load 20, a variable resistor zero adjustment circuit 30, a voltage regulation circuit 40, and a DC power supply 10 connected in sequence. The second resistor R2 is in parallel with the negative temperature coefficient thermistor NTC1. The cathode of the three-terminal voltage regulator N1 is connected to the DC power supply 10. The anode of the three-terminal voltage regulator N1 is connected to the first end of the negative temperature coefficient thermistor NTC1. The reference terminal of the three-terminal voltage regulator N1 is connected to the second end of the negative temperature coefficient thermistor NTC1. The anode of the three-terminal voltage regulator N1 is connected to the power supply terminal of the load 20. The load 20 includes a differential amplifier circuit 201 and a variable resistor amplitude adjustment circuit 202 connected in sequence. The output terminal of the load 20 outputs Vout externally. The signal of the constant current power supply circuit with temperature compensation function is amplified and processed and then output. The variable resistor amplitude adjustment circuit is used to set the amplification factor.

[0066] It should be noted that Figure 6 the second resistor R2 shown in is taken as an example of a shunt resistor, and it is not limited to only this combination of parallel resistors.

[0067] Next, in combination with Figure 7 the circuit schematic diagram of the load device according to a specific embodiment of the present invention shown, the load device will be described in detail:

[0068] The differential amplifier circuit 201 includes: a first operational amplifier U1A, a tenth resistor R10, an eleventh resistor R11, a twelfth resistor R12, and a low-pass filter. One output terminal of the second load H2 is connected to the positive input terminal of the first operational amplifier U1A through the tenth resistor R10. The other output terminal of the second load H2 is connected to the negative input terminal of the first operational amplifier U1A through the eleventh resistor R11. The negative input terminal of the first operational amplifier U1A is connected to the output terminal of the first operational amplifier U1A through the twelfth resistor R12. The output terminal of the first operational amplifier U1A outputs externally through the low-pass filter.

[0069] Optionally, different filters are selected according to the output requirements. In this embodiment, a T-type low-pass filter is taken as an example, which includes an eighteenth resistor R18, a nineteenth resistor R19, and a first capacitor C1. The output terminal of the first operational amplifier U1A outputs through the eighteenth resistor R18 and the nineteenth resistor R19. One end of the first capacitor C1 is connected to the second end of the eighteenth resistor R18 and the first end of the nineteenth resistor R19. The other end of the first capacitor C1 is grounded.

[0070] It should be noted that the variable resistor amplitude adjustment circuit 202 includes two or more resistors. The two or more resistors can be arbitrarily combined, such as being connected in series with each other, in parallel with each other, or some resistors in series and some resistors in parallel, as long as the total resistance value can be changed when one or more resistors are connected or left unconnected through the pads. The specific setting method of the resistors is not limited in the present invention.

[0071] For the convenience of description, in this embodiment, the variable resistor amplitude adjustment circuit 202 includes four resistors as an example. Optionally, the variable resistor amplitude adjustment circuit 202 is used for amplitude adjustment and includes: a thirteenth resistor R13, a fourteenth resistor R14, a fifteenth resistor R15, and a sixteenth resistor R16. One end of the circuit after the thirteenth resistor R13 and the fourteenth resistor R14 are connected in parallel is connected in series with one end of the circuit after the fifteenth resistor R15 and the sixteenth resistor R16 are connected in parallel. The connection point after the thirteenth resistor R13 and the fourteenth resistor R14 are connected in parallel and the fifteenth resistor R15 and the sixteenth resistor R16 are connected in parallel is connected to the inverting input terminal of the first operational amplifier U1A through a twelfth resistor R12. The other end after the thirteenth resistor R13 and the fourteenth resistor R14 are connected in parallel is connected to the output terminal of the first operational amplifier U1A; the thirteenth resistor R13, the fourteenth resistor R14, the fifteenth resistor R15, and the sixteenth resistor R16 are respectively connected or left unconnected through pads.

[0072] In a specific embodiment, the constant current power supply circuit includes a three-terminal voltage regulator N1, a diode D1, a negative temperature coefficient thermistor NTC1, a first resistor R1, a second resistor R2, and a third resistor R3; the model of the three-terminal voltage regulator is one of TL431, CJ431, and AZ431. The load 20 includes a first load H1 and a second load H2. The power supply terminals of the first load H1 and the second load H2 are connected, and the output terminals of the first load H1 and the second load H2 are connected; the input terminal of the differential amplifier circuit 201 is connected to the output terminal of the second load H2, the variable resistor zero adjustment circuit 30, and the variable resistor amplitude adjustment circuit 202. The variable resistor zero adjustment circuit 30 is connected to the voltage regulator circuit 40, and the variable resistor amplitude adjustment circuit 202 is connected to the other input terminal and the output terminal of the differential amplifier circuit 201. The differential amplifier circuit 201 outputs a voltage Vout.

[0073] In a specific embodiment, the cathode of the three-terminal voltage regulator N1 is connected to the positive terminal of the DC power supply 10, the anode of the three-terminal voltage regulator N1 is connected to the cathode of the diode D1, the first terminal of the negative temperature coefficient thermistor NTC1, a power supply terminal of the first load H1, and a power supply terminal of the second load H2. The reference terminal of the three-terminal voltage regulator N1 is connected to the second terminal of the negative temperature coefficient thermistor NTC1 through the first resistor R1 and the third resistor R3. The anode of the diode D1 is connected to one end of the first resistor R1 and the third resistor R3 through the second resistor R2.

[0074] In a specific embodiment, the differential amplifier circuit includes a first operational amplifier U1A, a tenth resistor R10, an eleventh resistor R11, a twelfth resistor R12, and a low-pass filter. An output terminal of the second load H2 is connected to the positive input terminal of the first operational amplifier U1A through the tenth resistor R10. Another output terminal of the second load H2 is connected to the negative input terminal of the first operational amplifier U1A through the eleventh resistor R11. The negative input terminal of the first operational amplifier U1A is connected to the output terminal of the first operational amplifier U1A through the twelfth resistor R12 and the variable resistor amplitude adjustment circuit 202. The output terminal of the first operational amplifier U1A outputs Vout through the low-pass filter.

[0075] In a specific embodiment, the variable resistor amplitude adjustment circuit 202 includes: a thirteenth resistor R13, a fourteenth resistor R14, a fifteenth resistor R15, and a sixteenth resistor R16. One end of the circuit after the thirteenth resistor R13 and the fourteenth resistor R14 are connected in parallel is connected in series with one end of the circuit after the fifteenth resistor R15 and the sixteenth resistor R16 are connected in parallel. The connection point after the thirteenth resistor R13 and the fourteenth resistor R14 are connected in parallel and the fifteenth resistor R15 and the sixteenth resistor R16 are connected in parallel is connected to the negative input terminal of the first operational amplifier through the twelfth resistor R12. The other end of the circuit after the thirteenth resistor R13 and the fourteenth resistor R14 are connected in parallel is connected to the output terminal of the first operational amplifier U1A. The other end of the circuit after the fifteenth resistor R15 and the sixteenth resistor R16 are connected in parallel is grounded through the seventeenth resistor R17. The low-pass filter includes an eighteenth resistor R18, a nineteenth resistor R19, and a first capacitor C1. The output terminal of the first operational amplifier U1A outputs through the eighteenth resistor R18 and the nineteenth resistor R19. One end of the first capacitor C1 is connected to the second terminal of the eighteenth resistor R18 and the first terminal of the nineteenth resistor R19. The other end of the first capacitor C1 is grounded.

[0076] In a specific embodiment, an output terminal of the second load H2 is connected to a variable resistor zero-point adjustment circuit 30 through a tenth resistor R10, a twenty-second resistor R22, and a twentieth resistor R20. The variable resistor zero-point adjustment circuit 30 includes a sixth resistor R6, a seventh resistor R7, an eighth resistor R8, and a ninth resistor R9. The voltage stabilization circuit 40 includes a first voltage-stabilizing diode Q1, a second voltage-stabilizing diode Q2, a fourth resistor R4, and a fifth resistor R5. The anode of the first voltage-stabilizing diode Q1 is connected to the cathode of the second voltage-stabilizing diode Q2. One end of the circuit after the sixth resistor R6 and the seventh resistor R7 are connected in parallel is connected in series with one end of the circuit after the eighth resistor R8 and the ninth resistor R9 are connected in parallel. The connection point of the circuit after the sixth resistor R6 and the seventh resistor R7 are connected in parallel and the circuit after the eighth resistor R8 and the ninth resistor R9 are connected in parallel is connected to the output terminal of the second load H2 and the positive input terminal of the first operational amplifier U1A through a plurality of resistors. The other end of the circuit after the sixth resistor R6 and the seventh resistor R7 are connected in parallel is connected to the cathode of the first voltage-stabilizing diode Q1 and is connected to the positive terminal of the DC power supply 10 through the fourth resistor R4. The other end of the circuit after the eighth resistor R8 and the ninth resistor R9 are connected in parallel is connected to the anode of the second voltage-stabilizing diode Q2 and is connected to the negative terminal of the DC power supply 10 through the fifth resistor R5.

[0077] In this embodiment, taking the load 20 as a Hall current sensor as an example, optionally, a first load H1 and a second load H2 connected to each other are provided. For products with a large current and a large magnetic core through-hole, the two Hall elements can be adjusted to each other to reduce the position error of the current-carrying rod flowing through the Hall sensor, thereby improving the accuracy of the measured current. The load 20 includes a first load H1 and a second load H2. The power supply terminals of the first load H1 and the second load H2 are connected, and the output terminals of the first load H1 and the second load H2 are connected. The first load H1 and the second load H2 refer to Hall elements. The number of loads is adjusted according to actual requirements. For example, setting one load H1 can also achieve the effect of the present invention. The power supply terminal of the first load H1 is connected to the anode of the three-terminal voltage-stabilizing diode N1, the cathode of the diode D1, and one end of the negative temperature coefficient thermistor NTC1. The output terminal of the second load H2 is connected to the variable resistor zero-point adjustment circuit 30, the differential amplification circuit 201, and the variable resistor amplitude adjustment circuit 202.

[0078] The constant current power supply circuit of the present utility model includes a three-terminal voltage regulator N1 and a negative temperature coefficient thermistor NTC1. Temperature compensation is achieved through the negative temperature coefficient thermistor NTC1 and the diode D1. While enhancing temperature compensation, it saves components, reduces costs and improves product stability. The following takes the load 20 as a Hall current sensor as an example to illustrate the specific compensation principle. A diode D1 is added in front of the input end of the negative temperature coefficient thermistor NTC1 to play a role in partial temperature compensation. When the temperature rises, due to the characteristics of the magnetic core, the magnetic field strength input to the Hall becomes weaker, resulting in a smaller output of the Hall element. As the temperature rises, the voltage drop across the diode decreases, and the resistance of the negative temperature coefficient thermistor NTC1 also decreases due to the increase in temperature. According to Ohm's law, the voltage across the negative temperature coefficient thermistor NTC1 rises, the current passing through the Hall element becomes larger, and the output of the Hall element becomes larger, thus achieving compensation.

[0079] The above description is only the preferred embodiment of the present application and an explanation of the technical principles applied. Those skilled in the art should understand that the scope of the utility model involved in the present application is not limited to the technical solution formed by the specific combination of the above technical features, but should also cover other technical solutions formed by any combination of the above technical features or their equivalent features without departing from the above inventive concept. For example, the technical solutions formed by mutually replacing the above features with the (but not limited to) technical features with similar functions disclosed in the present application.

Claims

1. A constant current power supply circuit with temperature compensation, characterized in that It includes a three-terminal voltage regulator, a negative temperature coefficient thermistor and at least one shunt resistor. The shunt resistor is connected in parallel with the negative temperature coefficient thermistor. The cathode of the three-terminal voltage regulator is connected to a DC power supply. The anode of the three-terminal voltage regulator is connected to the first end of the negative temperature coefficient thermistor. The reference terminal of the three-terminal voltage regulator is connected to the second end of the negative temperature coefficient thermistor. The anode of the three-terminal voltage regulator is connected to the power supply terminal of the load.

2. The constant current power supply circuit according to claim 1, wherein It further includes a diode, and the diode is connected in parallel with the negative temperature coefficient thermistor.

3. The constant current power supply circuit according to claim 2, wherein The cathode of the three-terminal voltage regulator is connected to the positive terminal of the DC power supply. The anode of the three-terminal voltage regulator is connected to the cathode of the diode, the first end of the negative temperature coefficient thermistor, and the power supply terminal of the load. The reference terminal of the three-terminal voltage regulator is connected to the second end of the negative temperature coefficient thermistor through a first resistor and a third resistor. The anode of the diode is connected to one end of the first resistor and the third resistor through a second resistor.

4. The constant current power supply circuit according to claim 1, characterized in that, The model selected for the three-terminal voltage regulator is one of TL431, CJ431 and AZ431.

5. The constant current power supply circuit according to claim 3, characterized in that, It further includes a voltage stabilizing circuit and a variable resistor zero-point adjustment circuit connected to each other, and the output terminal of the load is connected to the variable resistor zero-point adjustment circuit.

6. A load device, characterized in that, It includes a load and the constant current power supply circuit according to any one of claims 1 to 5.

7. The load device according to claim 6, characterized in that, The load includes a first load and a second load. The power supply terminals of the first load and the second load are connected to each other, and the output terminals of the first load and the second load are connected to each other.

8. The load device according to claim 7, characterized in that, The load includes a Hall current sensor, and the first load and the second load include Hall elements.

9. The load device according to claim 7, characterized in that, The load further includes a differential amplifier circuit. The input terminal of the differential amplifier circuit is connected to the output terminals of the first load and the second load, and the output terminal of the differential amplifier circuit outputs externally.

10. The load device according to claim 9, characterized in that, The load further includes a variable resistor amplitude adjustment circuit, and the variable resistor amplitude adjustment circuit is connected to the differential amplifier circuit.

Images