A topology of an open loop current sensor drive circuit with temperature compensation

Abstract

The application provides a topology structure of an open-loop current sensor driving circuit with temperature compensation, which comprises a HALL current sensor H1, a triode Q1, a triode Q2, a resistor R4 and an adjustable voltage stabilizing circuit; one end of the HALL current sensor H1 is connected with the collector of the triode Q1, and the other end is grounded; the base of the triode Q1 is connected with the emitter of the triode Q2; the collector of the triode Q2 is connected with a connecting line; the base of the triode Q2 is also connected with the connecting line; one end of the connecting line is connected with the adjustable voltage stabilizing circuit, and the other end is grounded; the resistor R4 is arranged on the connecting line between the emitter of the triode Q2 and the ground; the emitter of the triode Q1 is connected with a voltage input end VCC; one end of the adjustable voltage stabilizing circuit is connected with the connecting line, and the other end is connected with the voltage input end VCC. The topology structure of the open-loop current sensor driving circuit with temperature compensation guarantees the temperature drift characteristic of the open-loop HALL current sensor, and the consistency of the product is good.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of current sensor, in particular to a topology structure of open loop current sensor driving circuit with temperature compensation. BACKGROUND

[0002] The current open loop HALL current sensor generally has unreasonable temperature compensation circuit design, which leads to the temperature compensation of the current sensor failing to meet the needs of customers. The HALL element generally adopts gallium arsenide (GaAs) technology, which has good linearity. Since the input and output impedance of the gallium arsenide HALL element changes more with temperature, the power supply circuit of the HALL element is designed into a constant current driving form with temperature compensation.

[0003] The existing driving circuit design has a temperature drift of 0.4 mV / ℃ for the zero point of the open loop HALL current sensor and a temperature drift of 0.1% / ℃ for the gain in the temperature range of -40℃ to 85℃. In the case of higher performance requirements of customers on the product, this design cannot meet the needs of customers, and it is urgent to find an innovative temperature compensation circuit to meet the needs of customers.

[0004] The present application aims to realize the temperature compensation of the zero point and the gain of the open loop HALL sensor by designing a brand new driving circuit with temperature compensation, and meet the performance needs of customers. SUMMARY

[0005] Therefore, the present application aims to provide a topology structure of open loop current sensor driving circuit with temperature compensation to solve the problem of poor performance of the existing open loop HALL current sensor.

[0006] To achieve the above-mentioned purpose, the technical scheme of the present application is as follows:

[0007] A topology structure of open loop current sensor driving circuit with temperature compensation, comprising a HALL current sensor H1, a transistor Q1, a transistor Q2, a resistor R4 and an adjustable voltage stabilizing circuit.

[0008] One end of the HALL current sensor H1 is connected to the collector of the transistor Q1, and the other end is grounded. The base of the transistor Q1 is connected to the emitter of the transistor Q2. The collector of the transistor Q2 is connected to a connection line. The base of the transistor Q2 is also connected to the connection line. One end of the connection line is connected to the adjustable voltage stabilizing circuit, and the other end is grounded. The resistor R4 is arranged on the connection line between the emitter of the transistor Q2 and the ground.

[0009] The emitter of the transistor Q1 is connected to a voltage input end VCC. One end of the adjustable voltage stabilizing circuit is connected to the connection line, and the other end is connected to the voltage input end VCC.

[0010] Further, the adjustable voltage stabilizing circuit comprises a potentiometer R2, a resistor R3 and a three-terminal adjustable voltage stabilizer Z1, the output end of the three-terminal adjustable voltage stabilizer Z1 is connected with the voltage input end VCC, the input end of the three-terminal adjustable voltage stabilizer Z1 is connected with the connecting line, the output end of the three-terminal adjustable voltage stabilizer Z1 is connected with the potentiometer R2 and the resistor R3 in parallel, one end of the potentiometer R2 is connected with R3, the other end is connected with the voltage input end VCC, the other end of the resistor R3 is connected with the connecting line.

[0011] The common end of the three-terminal adjustable voltage stabilizer Z1 is electrically connected with the connecting line between the potentiometer R2 and the resistor R3.

[0012] Further, the potentiometer R2 is a variable resistor.

[0013] Further, the resistor R1 is further connected between the emitter of the triode Q1 and the voltage input end VCC.

[0014] Compared with the prior art, the topology structure of the open-loop current sensor driving circuit with temperature compensation has the following advantages:

[0015] The topology structure of the open-loop current sensor driving circuit with temperature compensation has good thermal stability, the three-terminal adjustable voltage stabilizer Z1 and the related circuit design with good switching characteristics and low temperature coefficient can guarantee that the product circuit is simple and effective, and the selection of the key three-terminal adjustable voltage stabilizer has small temperature influence on the size of the driving constant-current IC; the temperature drift characteristic of the open-loop HALL current sensor is guaranteed, and the consistency of the product is good. BRIEF DESCRIPTION OF DRAWINGS

[0016] The accompanying drawings, which form a part of the present application, are used to provide further understanding of the present application, and serve as an aid in explaining the present application. The schematic embodiments of the present application and their descriptions serve to explain the present application, and do not constitute improper limitations on the present application. In the drawings:

[0017] Figure 1 It is a structural diagram of the existing open-loop current sensor driving circuit with temperature compensation;

[0018] Figure 2 It is a structural diagram of the open-loop current sensor driving circuit with temperature compensation of the present application. DETAILED DESCRIPTION

[0019] It should be noted that the embodiments in the present application and the features in the embodiments can be combined with each other without conflict.

[0020] In the description of the present application, it is to be understood by the terms "center", "longitudinal", "lateral", "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, only for the convenience of describing the present application and simplifying the description, and not indicating or implying that the indicated device or element must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the present application. In addition, the terms "first", "second" and the like are only for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined with "first", "second" and the like can be explicitly or implicitly included one or more. In the description of the present application, unless otherwise stated, the meaning of "a plurality of" is two or more.

[0021] In the description of the present application, it should be noted that unless otherwise explicitly specified and limited, the terms "mounting", "connection", "connection" should be understood broadly, for example, it can be fixedly connected, or it can be detachably connected, or integrally connected; it can be mechanically connected, or it can be electrically connected; it can be directly connected, or it can be indirectly connected through an intermediate medium, or it can be connected inside two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood through specific circumstances.

[0022] The present application will be described in detail below with reference to the accompanying drawings and in conjunction with embodiments.

[0023] The existing drive circuit with temperature compensation is shown in Figure 1 Q1 is a PNP transistor, H1 is a HALL current sensor, Z1 is a voltage stabilizing diode for outputting a stable reference voltage. D1 is a diode for compensating the temperature drift of the constant current drive circuit caused by the voltage stabilizing diode Z1. As shown in the figure, the constant current I C The calculation formula of the size is:

[0024]

[0025] In the formula:

[0026] V Z1 : the voltage stabilizing value of the voltage stabilizing diode Z1

[0027] V D1 : the on-voltage drop of the diode D1

[0028] V BE : the voltage between the B-E of the transistor Q1.

[0029] When the temperature rises, VZ1 The increase, select and similar temperature characteristics of the voltage regulator tube, then V D1 Also increase, so as to keep the output current IC constant. The advantage of this circuit is that the number of components is small; the disadvantage is that it is difficult to select the voltage regulator tube and the diode with the same temperature characteristics, which leads to the constant current I C Affected by temperature, temperature compensation is difficult to adjust, resulting in large temperature drift of the zero point and gain of the HALL current sensor.

[0030] As Figure 2 shown, a topology of an open-loop current sensor drive circuit with temperature compensation includes a HALL current sensor H1, a triode Q1, a triode Q2, a resistor R4, and an adjustable voltage regulator circuit.

[0031] One end of the HALL current sensor H1 is connected to the collector of the triode Q1, and the other end is grounded. The base of the triode Q1 is connected to the emitter of the triode Q2. The collector of the triode Q2 is connected to a connection line. The base of the triode Q2 is also connected to the connection line. One end of the connection line is connected to the adjustable voltage regulator circuit, and the other end is grounded. The resistor R4 is arranged on the connection line between the emitter of the triode Q2 and the ground.

[0032] The emitter of the triode Q1 is connected to a voltage input end VCC. One end of the adjustable voltage regulator circuit is connected to the connection line, and the other end is connected to the voltage input end VCC.

[0033] The adjustable voltage regulator circuit includes a potentiometer R2, a resistor R3, and a three-terminal adjustable voltage regulator Z1. The output end of the three-terminal adjustable voltage regulator Z1 is connected to the voltage input end VCC. The input end of the three-terminal adjustable voltage regulator Z1 is connected to the connection line. The output end of the three-terminal adjustable voltage regulator Z1 is connected in parallel with the potentiometer R2 and the resistor R3. One end of the potentiometer R2 is connected to R3, and the other end is connected to the voltage input end VCC. The other end of the resistor R3 is connected to the connection line.

[0034] The common end of the three-terminal adjustable voltage regulator Z1 is electrically connected to the connection line between the potentiometer R2 and the resistor R3.

[0035] Among them, the potentiometer R2 is a variable resistor. The emitter of the triode Q1 and the voltage input end VCC are also connected to a resistor R1.

[0036] An implementation method of an open-loop current sensor drive circuit with temperature compensation can be implemented based on the above topology.

[0037] The application relates to a circuit structure of a HALL current sensor constant current circuit with temperature compensation, which is composed of a three-terminal adjustable voltage stabilizer Z1, a variable potentiometer R2, transistors Q1 and Q2, and resistors R1, R3 and R4. The three-terminal adjustable voltage stabilizer Z1 with good temperature characteristics is the key to the design of the driving circuit. Thus, the temperature drift characteristics of the zero point and the gain, and the consistency of the product are solved.

[0038] (1) The working principle analysis of the constant current output of the circuit of the application is as follows: when the change of a factor (such as temperature) causes the driving current of the HALL current sensor in the loop to increase, the base current of Q2 increases, thereby causing the base current of Q1 to rapidly increase. Since the increase amplitude of the base current of Q1 is greater than that of the emitter current, according to Kirchhoff's current law, the collector current of Q1, that is, the driving current of the HALL current sensor, is determined to decrease, thereby realizing the constant current output of the HALL current sensor. In the same way, when the driving current of the HALL current sensor decreases, the circuit can also realize constant current output.

[0039] (2) The three-terminal adjustable voltage stabilizer with a reference voltage of V REF is selected. Since the working current of the voltage reference output end is 0.7 mu A, which can be ignored, the current flowing through R2 and R3 is equal, and the voltage across R4 is:

[0040]

[0041] The driving current I C of the HALL current sensor is:

[0042]

[0043] (3) According to formulas (2) and (3), the size of the driving current I C of the improved constant current driving circuit is not affected by the supply voltage V CC , the change rate of the reference output voltage of the three-terminal adjustable voltage stabilizer Z1 is very low, and the supply current I C of the HALL current sensor is determined by R1, R2 and R3, and the size of the driving current I C can be adjusted through the potentiometer R2.

[0044] As analyzed above, under the condition that the resistance value of the potentiometer is unchanged, the size of the driving current IC is changed only by the reference output voltage of the three-terminal adjustable voltage stabilizer Z1, so that the temperature drift characteristics of the zero point and the gain of the open-loop HALL current sensor are obviously improved, and the consistency thereof can be well guaranteed. Thus, the design purpose is achieved.

[0045] The above merely provides the preferred embodiment of the present application, and is not used to limit the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A topology of an open loop current sensor drive circuit with temperature compensation, characterized by: The adjustable voltage stabilizing circuit comprises a potentiometer R2, a resistor R3 and a three-terminal adjustable voltage stabilizer Z1. One end of the HALL current sensor H1 is connected to the collector of the transistor Q1, and the other end is grounded. The base of the transistor Q1 is connected to the emitter of the transistor Q2. The collector of the transistor Q2 is connected to a connecting line. The base of the transistor Q2 is also connected to the connecting line. One end of the connecting line is connected to the adjustable voltage stabilizing circuit, and the other end is connected to the ground through the resistor R4. One end of the resistor R4 is connected to the collector of the transistor Q2, and the other end is grounded. The emitter of the transistor Q1 is connected to the voltage input terminal VCC. One end of the adjustable voltage stabilizing circuit is connected to the connecting line, and the other end is connected to the voltage input terminal VCC. The adjustable voltage stabilizing circuit comprises a potentiometer R2, a resistor R3 and a three-terminal adjustable voltage stabilizer Z1. The output terminal of the three-terminal adjustable voltage stabilizer Z1 is connected to the voltage input terminal VCC. The input terminal of the three-terminal adjustable voltage stabilizer Z1 is connected to the connecting line. The output terminal of the three-terminal adjustable voltage stabilizer Z1 is connected in parallel with the potentiometer R2 and the resistor R3. One end of the potentiometer R2 is connected to R3, and the other end is connected to the voltage input terminal VCC. The other end of the resistor R3 is connected to the connecting line. The common terminal of the three-terminal adjustable voltage stabilizer Z1 is electrically connected to the connecting line between the potentiometer R2 and the resistor R3. The potentiometer R2 is a variable resistor. The three-terminal adjustable voltage regulator is selected as the reference voltage V REF The working current of the three-terminal adjustable voltage regulator is 0.7 μA, which can be ignored. The current flowing through R2 and R3 is equal, and the voltage across the resistor R4 is: The drive current I of the HALL current sensor C is: V BE VBE is the voltage between the B-E terminals of the transistor Q1; According to the two formulas above, the driving current I C The size of the power supply voltage V CC The change rate of the reference output voltage of the three-terminal adjustable voltage regulator Z1 is low, and the supply current I C Of the HALL current sensor is only determined by R1, R2, R3, and the driving current I C The size can be adjusted by the potentiometer R2.

2. The topology of open loop current sensor drive circuit with temperature compensation according to claim 1, characterized in that: The emitter of the transistor Q1 is also connected to the voltage input terminal VCC through the resistor R1.

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