A high-precision temperature sampling circuit based on single-chip microcomputer operation

Abstract

The utility model discloses a temperature sampling circuit belongs to switching power supply technical field, specifically relates to a kind of high-precision temperature sampling circuit based on single-chip microcontroller operation, comprising: voltage follower, voltage division network module and RC filter filter module;The voltage division network module is connected with the input end of the voltage follower, and the input end of the RC filter filter module is connected with the output end of the voltage follower, and the output end is connected with the AD mouth of MCU;The utility model increases voltage follower between MCU-AD mouth and voltage division network, guarantees the voltage stability of voltage division network, increases the interference in RC filter filter circuit simultaneously, further increases the accuracy of sampling, so that some cheap lower input impedance and lower sensitivity MCU can also test the good precision under low temperature state in the use of circuit, so that the utility model is compared with previous technology, cost is reduced obviously, and the detection precision of low temperature is improved.

Description

Technical Field

[0001] This utility model discloses a temperature sampling circuit, belonging to the field of switching power supply technology, specifically involving a high-precision temperature sampling circuit based on microcontroller operation. Background Technology

[0002] Conventional NTC resistors have resistance values ​​as high as several hundred kilohertz or even megohms at low temperatures. To balance this with low resistance values ​​at high temperatures, the voltage divider network is usually powered by 3.3V. This ensures that the voltage limit of the MCU-AD port will not exceed the MCU supply voltage of 3.3V at high temperatures. However, with a supply voltage of 3.3V, the sampling current becomes very small at low temperatures. Conventional MCU-AD sampling will consume some current, leading to inaccurate temperature sampling. The conventional solution to this problem is to purchase a higher precision MCU with higher input impedance, but this increases the cost. Utility Model Content

[0003] Purpose of this utility model: To provide a high-precision temperature sampling circuit based on microcontroller operation, and to solve the problems mentioned above.

[0004] Technical solution: A high-precision temperature sampling circuit based on microcontroller operation, the temperature sampling circuit includes: a voltage follower, a voltage divider network module and an RC filter module;

[0005] In a further embodiment, the voltage divider network module is connected to the input terminal of the voltage follower, the input terminal of the RC filter module is connected to the output terminal of the voltage follower, and the output terminal is connected to the AD port of the MCU;

[0006] The voltage follower includes: a rail-to-rail operational amplifier A19;

[0007] The voltage divider network module includes: an NTC negative temperature coefficient thermistor RT1 and a voltage divider resistor R1;

[0008] The RC filter module includes a resistor R2 and a capacitor C1.

[0009] In a further embodiment, one end of the voltage divider resistor R1 and one end of the NTC negative temperature coefficient thermistor RT1 are connected to pin 3 of the rail-to-rail operational amplifier A19, the other end of the voltage divider resistor R1 is input with a 3.3V voltage, and the other end of the NTC negative temperature coefficient thermistor RT1 is grounded to GND.

[0010] In a further embodiment, pin 5 of the rail-to-rail operational amplifier A19 receives a 3.3V voltage, and pin 2 of the rail-to-rail operational amplifier A19 is grounded to GND.

[0011] In a further embodiment, one end of the resistor R2 is connected to both pin 1 and pin 4 of the rail-to-rail operational amplifier A19, one end of the capacitor C1 is connected to the other end of the resistor R2 and connected to the AD port of the MCU, and the other end of the capacitor C1 is grounded to GND.

[0012] Beneficial effects: This invention adds a voltage follower between the MCU-AD port and the voltage divider network, ensuring the voltage stability of the voltage divider network. At the same time, it adds an RC filter to remove interference in the circuit and further increases the sampling accuracy. This allows even some inexpensive MCUs with lower input impedance and lower sensitivity to achieve good accuracy at low temperatures. Therefore, compared with previous technologies, this invention significantly reduces costs and improves the detection accuracy at low temperatures. Attached Figure Description

[0013] Figure 1 This is a schematic diagram of the temperature sampling circuit of this utility model. Detailed Implementation

[0014] The technical solution of this utility model will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this utility model. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this utility model.

[0015] In the description of this utility model, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the accompanying drawings and are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this utility model. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0016] In the description of this utility model, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model based on the specific circumstances. Furthermore, the technical features involved in the different embodiments of this utility model described below can be combined with each other as long as they do not conflict with each other.

[0017] A high-precision temperature sampling circuit based on microcontroller operation includes: a voltage follower, a voltage divider network module, and an RC filter module;

[0018] In one embodiment, such as Figure 1 As shown, the voltage divider network module is connected to the input terminal of the voltage follower, the input terminal of the RC filter module is connected to the output terminal of the voltage follower, and the output terminal is connected to the AD port of the MCU;

[0019] The voltage follower includes: a rail-to-rail operational amplifier A19;

[0020] The voltage divider network module includes: an NTC negative temperature coefficient thermistor RT1 and a voltage divider resistor R1;

[0021] The RC filter module includes a resistor R2 and a capacitor C1.

[0022] In one embodiment, such as Figure 1 As shown, one end of the voltage divider resistor R1 and one end of the NTC negative temperature coefficient thermistor RT1 are connected to pin 3 of the rail-to-rail operational amplifier A19. The other end of the voltage divider resistor R1 is input with a voltage of 3.3V, and the other end of the NTC negative temperature coefficient thermistor RT1 is grounded to GND.

[0023] In one embodiment, such as Figure 1 As shown, pin 5 of the rail-to-rail operational amplifier A19 receives a 3.3V voltage, and pin 2 of the rail-to-rail operational amplifier A19 is grounded (GND).

[0024] In one embodiment, such as Figure 1 As shown, one end of the resistor R2 is connected to both pin 1 and pin 4 of the rail-to-rail operational amplifier A19. One end of the capacitor C1 is connected to the other end of the resistor R2 and to the AD port of the MCU. The other end of the capacitor C1 is grounded to GND.

[0025] Working Principle: This invention employs an NTC negative temperature coefficient thermistor RT1, which exhibits different resistance values ​​under different temperature conditions. R1 is a voltage divider resistor, A19 is a rail-to-rail operational amplifier, R2 and C1 form an RC filter, and MCU-AD is the microcontroller's AD sampling port, responsible for converting the sampled voltage signal into a temperature signal. The voltage divider resistor R1 and the NTC negative temperature coefficient thermistor RT1 form a voltage divider network, powered by 3.3V. This voltage divider network can provide different voltages at different temperatures to the positive input port of the rail-to-rail operational amplifier A19. The negative input port of the rail-to-rail operational amplifier A19 is connected to the output to form an output voltage follower, so the voltage of the positive input is equal to the voltage of the operational amplifier's output. The RC network filters out interference at the output port and provides the signal to the AD sampling port. The microcontroller uses a pre-set voltage-temperature relationship to calculate the corresponding temperature.

[0026] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the protection scope of this invention.

Claims

1. A high-precision temperature sampling circuit based on microcontroller operation, characterized in that, The temperature sampling circuit includes: a voltage follower, a voltage divider network module, and an RC filter module; The voltage divider network module is connected to the input terminal of the voltage follower, and the input terminal of the RC filter module is connected to the output terminal of the voltage follower, and the output terminal is connected to the AD port of the MCU. The voltage follower includes: a rail-to-rail operational amplifier A19; The voltage divider network module includes: an NTC negative temperature coefficient thermistor RT1 and a voltage divider resistor R1; The RC filter module includes a resistor R2 and a capacitor C1.

2. The high-precision temperature sampling circuit based on microcontroller operation according to claim 1, characterized in that, One end of the voltage divider resistor R1 and one end of the NTC negative temperature coefficient thermistor RT1 are connected to pin 3 of the rail-to-rail operational amplifier A19. The other end of the voltage divider resistor R1 is input with a voltage of 3.3V, and the other end of the NTC negative temperature coefficient thermistor RT1 is grounded to GND.

3. The high-precision temperature sampling circuit based on microcontroller operation according to claim 1, characterized in that, The rail-to-rail operational amplifier A19 has a 3.3V input at pin 5 and is grounded at pin 2 (GND).

4. The high-precision temperature sampling circuit based on microcontroller operation according to claim 1, characterized in that, One end of the resistor R2 is connected to both pin 1 and pin 4 of the rail-to-rail operational amplifier A19. One end of the capacitor C1 is connected to the other end of the resistor R2 and to the AD port of the MCU. The other end of the capacitor C1 is grounded to GND.

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