A TMR current sensor power supply and temperature compensation circuit

Abstract

The application relates to a TMR current sensor power supply and temperature compensation circuit, which comprises the following steps: a. a power supply circuit composed of a voltage stabilizing diode Z1 and resistors R3 and R4 is used to supply power for a TMR sensor U1; b. an amplification circuit composed of an amplifier D1 and resistors R1, R2, R7, R8 and a capacitor C2; c. a driving push-pull circuit composed of connected triodes Q1 and Q2 and a resistor R9, the other end of the capacitor C2, the other end of the resistor R9 and the anodes of the Q1 and Q2 are connected to a driving coil L. Since the TMR current sensor has negative temperature characteristics, in order to compensate the temperature, the TMR power supply adopts 6.8V voltage stabilizing diode voltage stabilizing power supply. Since the 6.8V voltage stabilizing diode has positive temperature characteristics, when the temperature rises, the voltage stabilizing value of the voltage stabilizing diode increases, so that the TMR power supply voltage increases, the TMR output voltage increases, and thus the part of the TMR output which decreases due to the temperature increase can be effectively compensated, so that the TMR output is relatively stable with the temperature change.

Description

Technical Field

[0001] This invention belongs to the field of sensor manufacturing and relates to a power supply and temperature compensation short circuit for a TMR (tunnel magnetoresistance) current sensor. Background Technology

[0002] Tunnel magnetoresistive (TMR) devices are a new generation of magnetic sensors that are widely used in current measurement. Compared with traditional current sensors, they are smaller, more sensitive, and have better temperature stability, making them able to adapt to drastic changes in the temperature of the power grid environment. Furthermore, they are simple in structure, easy to manufacture, and inexpensive, making them suitable for large-scale promotion and use.

[0003] but TMR has negative temperature characteristics As the chip temperature rises, the chip's output voltage gradually decreases. In applications where the ambient temperature varies greatly, the TMR current sensor must be compensated for its negative temperature characteristic to reduce the output voltage shift caused by changes in ambient temperature. Summary of the Invention

[0004] The purpose of this invention is to provide a power supply and temperature compensation circuit for a TMR current sensor, so as to meet the power supply and temperature compensation of the TMR current sensor, reduce the temperature drift of the current sensor, improve the measurement accuracy of the sensor, and at the same time make the TMR zero-point output 0V.

[0005] The present invention adopts the following technical solution:

[0006] A power supply and temperature compensation circuit for a TMR current sensor, characterized by comprising:

[0007] a. The power supply circuit of the TMR sensor U1 consists of a Zener diode Z1 connected to one end of resistors R3 and R4 respectively. The other ends of resistors R3 and R4 are connected to the +12V and -12V power supply respectively. The Zener diode Z1 forms a stable voltage to power the TMR sensor U1. The Zener diode Z1 is also connected to one end of resistors R5 and R6 respectively. The other ends of resistors R5 and R6 are connected to form a common terminal.

[0008] b. The amplifier circuit consists of amplifier D1, resistors R1, R2, R7, R8, and capacitor C2. Input resistors R1 and R2 are connected to pins 2 and 3 of amplifier D1, respectively. The other ends of resistors R1 and R2 are connected to pins O of the TMR sensor U1. - O + One end of resistor R7 is connected to the common terminal of resistors R5 and R6, and the other end is connected to pin 3 of amplifier D1 and one end of R8. The other end of R8 is connected to one end of capacitor C2 to form an integrating filter circuit. The V+ and V- terminals of amplifier D1 are connected to the +12V and -12V power supply, respectively.

[0009] c. Push-pull drive circuit: The push-pull drive circuit is composed of connected transistors Q1 and Q2 and resistor R9. The collector of Q1 is connected to the power supply V+, the base of Q1 is connected to the output terminal 6 of amplifier D1, the base of Q2 and one end of resistor R9, the emitter of Q1 is connected to the emitter of Q2, the collector of Q2 is connected to the power supply V-, and the other end of capacitor C2, the other end of resistor R9 and the emitters of Q1 and Q2 are connected to the drive coil L.

[0010] Furthermore, capacitor C1 is connected to pins 1 and 8 of amplifier D1.

[0011] In this invention, since the TMR current sensor has a negative temperature characteristic, the chip's output voltage gradually decreases as the chip temperature rises. In addition, the TMR's operating current is very small, around 2mA. To compensate for temperature, the TMR is powered by a 6.8V Zener diode. Since the 6.8V Zener diode has a positive temperature characteristic, its voltage regulation value increases as the temperature rises. This increases the voltage supplied to the TMR, resulting in an increase in the TMR's output voltage. Thus, it can effectively compensate for the decrease in TMR output due to temperature increases, making the TMR output more stable with temperature changes. Attached image description:

[0012] Figure 1 This is the circuit schematic diagram of the present invention. Detailed Implementation

[0013] To provide a better understanding of the structural features of the present invention, a detailed description is provided below in conjunction with the accompanying drawings and embodiments. However, the present invention is not limited to the specific embodiments.

[0014] like Figure 1 As shown, the main components of the TMR current sensor power supply and temperature compensation circuit of the present invention are as follows:

[0015] 1. The power supply circuit for the TMR sensor U1 consists of a Zener diode Z1 connected to one end of resistors R3 and R4, respectively. The other ends of R3 and R4 are connected to +12V and -12V power supplies, respectively. The Zener diode Z1 forms a voltage of approximately ±3.4V (at room temperature) to power the TMR sensor U1. This circuit provides a temperature-compensated power supply, ensuring minimal temperature variation in the TMR output, with a zero-point output of 0V. When the measured current is positive, the voltage at the O+ terminal of the TMR sensor U1 is higher than the O- terminal voltage; when the measured current is negative, the voltage at the O+ terminal is lower than the O- terminal voltage. The TMR output VO (the voltage difference between the O+ and O- terminals) is linearly related to the measured current. The Zener diode Z1 is also connected to one end of resistors R5 and R6, with the other ends of R5 and R6 connected together to form a common terminal.

[0016] 2. Amplification Circuit: Amplifier D1, along with resistors R1, R2, R7, R8, and capacitor C2, forms the amplification section, which amplifies the TMR output into a directional voltage signal linearly related to the measured current. Input resistors R1 and R2 are connected to pins 2 (IN-) and 3 (IN+) of amplifier D1, respectively. The other ends of resistors R1 and R2 are connected to pins O- and O- of the TMR sensor U1, respectively. + end.

[0017] R7 is the zero-position adjustment input resistor. One end of it is connected to the common terminal of resistors R5 and R6, and the other end is connected to pin 3 of amplifier D1 and one end of R8. The other end of R8 is connected to one end of capacitor C2 to form an integrating filter circuit to eliminate ripple. Capacitor C1 is connected to pins 1 and 8 of amplifier D1 as a compensation capacitor. The V+ and V- terminals of amplifier D1 are connected to the +12V and -12V power supplies, respectively.

[0018] 3. Push-pull drive circuit: The push-pull drive circuit is composed of connected transistors Q1 and Q2 and resistor R9. Q1 and Q2 form the push-pull drive circuit, and resistor R9 increases the circuit response speed.

[0019] The collector of Q1 is connected to the power supply V+. The base of Q1 is also connected to pin 6 of the amplifier D1 output, the base of Q2, and one end of resistor R9. The emitter of Q1 is connected to the emitter of Q2, and the collector of Q2 is connected to the power supply V-. The other end of capacitor C2, the other end of resistor R9, and the emitters of Q1 and Q2 are all connected to the drive coil L.

[0020] When the amplifier outputs a directional voltage signal that is linearly related to the measured current, it drives the push-pull circuit. The push-pull circuit applies a voltage to the coil L, generating a directional current in the coil that is linearly related to the measured current.

Claims

1. A power supply and temperature compensation circuit for a TMR current sensor, characterized in that... include: a. The power supply circuit of the TMR sensor U1 consists of a Zener diode Z1 connected to one end of resistors R3 and R4 respectively. The other ends of resistors R3 and R4 are connected to the +12V and -12V power supply respectively. The Zener diode Z1 forms a stable voltage to power the TMR sensor U1. The Zener diode Z1 is also connected to one end of resistors R5 and R6 respectively. The other ends of resistors R5 and R6 are connected to form a common terminal. b. The amplifier circuit consists of amplifier D1, resistors R1, R2, R7, R8, and capacitor C2. Input resistors R1 and R2 are connected to pins 2 and 3 of amplifier D1, respectively. The other ends of resistors R1 and R2 are connected to pins O of the TMR sensor U1. - O + One end of resistor R7 is connected to the common terminal of resistors R5 and R6, and the other end is connected to pin 3 of amplifier D1 and one end of R8. The other end of R8 is connected to one end of capacitor C2 to form an integrating filter circuit. The V+ and V- terminals of amplifier D1 are connected to the +12V and -12V power supply, respectively. c. Push-pull drive circuit: The push-pull drive circuit is composed of connected transistors Q1 and Q2 and resistor R9. The collector of Q1 is connected to the power supply V+, the base of Q1 is connected to the output terminal 6 of amplifier D1, the base of Q2 and one end of resistor R9, the emitter of Q1 is connected to the emitter of Q2, the collector of Q2 is connected to the power supply V-, and the other end of capacitor C2, the other end of resistor R9 and the emitters of Q1 and Q2 are connected to the drive coil L.

2. The TMR current sensor power supply and temperature compensation circuit according to claim 1, characterized in that... Capacitor C1 is connected to pins 1 and 8 of amplifier D1.

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