Circuit for improving NTC sampling precision consistency

Abstract

The utility model discloses a circuit for improving NTC sampling precision consistency, which comprises a reference power supply circuit and an NTC sampling circuit, and is characterized in that the reference power supply circuit comprises a reference voltage stabilizing chip U1, a pin 1 of the reference voltage stabilizing chip U1 is respectively connected with one end of a resistor R3 and one end of a resistor R4, the other end of the resistor R3 is respectively connected with one end of a resistor R2 and a pin 2 of the reference voltage stabilizing chip U1, and the other end of the resistor R4 is connected with the other end of the resistor R2 and the other end of the reference voltage stabilizing chip U1. The other end of the resistor R2 is connected with a + 5V power supply, and the second pin of the reference voltage stabilization chip U1 is further connected with an NTC sampling circuit. The reference voltage stabilizing chip U1 is matched with the resistor R3 and the resistor R4, 5V input voltage is converted into 3V voltage, the 3V voltage is provided for the NTC sampling circuit and the microprocessor ADC reference input voltage, accurate 3V power supply of the NTC sampling circuit is achieved, accurate output of the 3V reference voltage can be guaranteed even if output voltage of a pre-stage power supply fluctuates, the accuracy of NTC sampling is improved, and the service life of the NTC sampling circuit is prolonged. And the reliability and the stability of the product are improved.

Description

TECHNICAL FIELD

[0001] The utility model belongs to NTC sampling precision control technical field, specifically related to a circuit that promotes NTC sampling precision consistency. BACKGROUND

[0002] In electronic technology, how to guarantee the ADC measurement consistency of NTC in the circuit after the batch production of products is very important for improving the reliability and stability of products.

[0003] Most of the existing schemes adopt the form of LDO or DC-DC direct current power supply to supply power to the whole circuit, but due to the poor consistency of the power supply voltage, the measurement error is large, which causes the poor consistency of the NTC temperature measurement data in the same batch of products, and cannot realize accurate measurement, which has a certain influence on the reliability and stability of the product.

[0004] Therefore, an NTC sampling precision consistency improving circuit is needed to improve the consistency and reliability of NTC temperature collection data. UTILITY MODEL CONTENTS

[0005] The utility model discloses a kind of circuit that promotes NTC sampling precision consistency, to solve the problems raised in the above background technology. The utility model provides a kind of circuit that promotes NTC sampling precision consistency, with the characteristics of improving the consistency and reliability of NTC temperature collection data.

[0006] To achieve the above object, the utility model provides the following technical scheme: a kind of circuit that promotes NTC sampling precision consistency, including reference power supply circuit and NTC sampling circuit, wherein, reference power supply circuit includes reference voltage stabilizing chip U1, the 1 foot of reference voltage stabilizing chip U1 is connected with the one end of resistance R3 and resistance R4 respectively, the other end of resistance R3 is connected with the one end of resistance R2 and the 2 foot of reference voltage stabilizing chip U1 respectively, the other end of resistance R2 is connected with +5V power supply, the 2 foot of reference voltage stabilizing chip U1 is also connected with NTC sampling circuit, the other end of resistance R4 and the 3 foot of reference voltage stabilizing chip U1 are all connected with ground terminal.

[0007] To be used for the output filtering of reference power supply circuit, further, there is capacitor C1 in parallel between the 2 foot and the 3 foot of reference voltage stabilizing chip U1.

[0008] To be used as upper end sampling resistance, further, the resistance of resistance R3 is 10K, and the accuracy is ±1%.

[0009] To be used as lower end sampling resistance, further, the resistance of resistance R4 is 50K, and the accuracy is ±1%.

[0010] In order to output 3V voltage accurately, further, the model of the reference voltage stabilizing chip U1 is TL431.

[0011] In order to obtain the temperature value of the current environment, further, the NTC sampling circuit comprises a thermistor RT1, one end of the thermistor RT1 is connected with the resistor R1 and the ADC pin of the microprocessor respectively, the other end of the resistor R1 is connected with the pin 2 of the reference voltage stabilizing chip U1, and the other end of the thermistor RT1 is connected with the ground end.

[0012] Further, the resistance value of the thermistor RT1 is 10K, and the precision is ±1%.

[0013] In order to filter the signal output of the NTC sampling circuit, further, the capacitor C2 is connected in parallel on the two ends of the thermistor RT1.

[0014] Compared with the prior art, the utility model has the beneficial effects that:

[0015] 1、 the utility model discloses a reference voltage stabilizing chip U1 is collocated with resistor R3 and resistor R4, and 5V input voltage is converted into 3V voltage, and is provided with NTC sampling circuit and microprocessor ADC reference input voltage respectively, realizes the accurate 3V power supply of NTC sampling circuit, even if the output voltage of the front stage power supply appears fluctuation, can guarantee the accurate output of reference voltage 3V, improves the accuracy of NTC sampling, and improves the reliability and stability of product.

[0016] 2、 the utility model discloses that thermistor RT1 is connected in series with resistor R1 and carries out voltage division to 3V reference power supply, and the voltage division value of thermistor RT1 changes along with the change of temperature, and the microprocessor carries out sampling and calculation to the voltage division value of the two ends of thermistor RT1 through the ADC pin, and obtains the temperature value of the current environment.

[0017] 3、 the utility model discloses simple structure, high reliability and the effect of cost. DRAWINGS

[0018] Fig. 1 It is the circuit diagram of the utility model;

[0019] Fig. 2 It is the circuit diagram of reference power supply circuit in the utility model;

[0020] Fig. 3 It is the circuit diagram of NTC sampling circuit in the utility model. CONCRETE IMPLEMENTATION

[0021] With reference to the drawings in the embodiments of the present application, the technical solutions in the embodiments of the present application will be clearly and completely described, obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of the present application.

[0022] Embodiment 1

[0023] Please refer to Figs. 1-3 The utility model provides the following technical scheme: a circuit that promotes NTC sampling precision consistency, including reference power supply circuit and NTC sampling circuit, wherein, reference power supply circuit includes reference voltage stabilizing chip U1, the model of reference voltage stabilizing chip U1 is TL431, the 1 pin of reference voltage stabilizing chip U1 is connected with the one end of resistance R3 and resistance R4 respectively, the other end of resistance R3 is connected with the one end of resistance R2 and the 2 pin of reference voltage stabilizing chip U1 respectively, the other end of resistance R2 is connected with +5V power supply, the 2 pin of reference voltage stabilizing chip U1 is also connected with NTC sampling circuit, the other end of resistance R4 and the 3 pin of reference voltage stabilizing chip U1 are all connected with ground terminal, the resistance of resistance R3 is 10K, and the precision is ±1%, the resistance of resistance R4 is 50K, and the precision is ±1%, resistance R2 is used for pre-stage voltage division and current limiting, and the resistance is 300Ω.

[0024] Through adopting the above technical scheme, the utility model through reference voltage stabilizing chip U1 collocation resistance R3 and resistance R4, convert 5V input voltage into 3V voltage, provide for NTC sampling circuit and microprocessor ADC reference input voltage respectively, realize the accurate 3V power supply of NTC sampling circuit, even if the output voltage of pre-stage power supply appears fluctuation, can guarantee the accurate output of reference voltage 3V, promote the accuracy of NTC sampling, and improve the reliability and stability of product.

[0025] Specifically, the NTC sampling circuit includes a thermistor RT1, the resistance of the thermistor RT1 is 10K, and the precision is ±1%, one end of the thermistor RT1 is connected with the resistance R1 and the ADC pin of the microprocessor respectively, the other end of the resistance R1 is connected with the 2 pin of the reference voltage stabilizing chip U1, and the other end of the thermistor RT1 is connected with the ground terminal.

[0026] Through adopting the above technical scheme, the voltage of 3V reference power supply is divided through the thermistor RT1 and the resistance R1 in series, the voltage division value of the thermistor RT1 changes with the change of temperature, and the microprocessor samples and calculates the voltage division value between the two ends of the thermistor RT1 through the ADC pin to obtain the temperature value of the current environment.

[0027] Embodiment 2

[0028] The difference between the embodiment and the embodiment 1 is that: specifically, the capacitor C1 is connected in parallel between the 2-pin and the 3-pin of the reference voltage stabilizing chip U1, and the capacitance of the capacitor C1 is 1uF.

[0029] By adopting the technical scheme, the output filtering of the reference power supply circuit is realized.

[0030] Embodiment 3

[0031] The difference between the embodiment and the embodiment 1 is that: specifically, the capacitor C2 is connected in parallel across the thermistor RT1, and the capacitance of the capacitor C2 is 100nF.

[0032] By adopting the technical scheme, the output filtering of the reference power supply circuit is realized.

[0033] In summary, the utility model discloses a reference voltage stabilizing chip U1 is matched with resistance R3 and resistance R4, and 5V input voltage is converted into 3V voltage, and is provided for NTC sampling circuit and microprocessor ADC reference input voltage respectively, realizes the accurate 3V power supply of NTC sampling circuit, even if the output voltage of the front stage power supply appears fluctuation, can guarantee the accurate output of reference voltage 3V, improves the accuracy of NTC sampling, and improves the reliability and stability of product, the utility model discloses that the thermistor RT1 is connected in series with resistance R1 to the voltage division of 3V reference power supply, and the voltage division value of thermistor RT1 changes along with the change of temperature, and the microprocessor carries out sampling and calculation to the voltage division value of thermistor RT1 two ends through the ADC pin, and obtains the temperature value of current environment, the utility model discloses simple structure, high reliability and the effect of cost.

[0034] Although the embodiments of the utility model have been shown and described, it can be understood by those skilled in the art that various changes, modifications, replacements and variations can be made to these embodiments without departing from the principles and spirits of the utility model, and the scope of the utility model is defined by the appended claims and their equivalents.

Claims

1. A circuit for improving the consistency of NTC sampling accuracy, characterized in that: The reference power supply circuit comprises a reference voltage stabilizing chip U1, one pin of the reference voltage stabilizing chip U1 is connected with one end of a resistor R3 and one end of a resistor R4 respectively, the other end of the resistor R3 is connected with one end of a resistor R2 and a second pin of the reference voltage stabilizing chip U1 respectively, the other end of the resistor R2 is connected with a +5V power supply, the second pin of the reference voltage stabilizing chip U1 is also connected with the NTC sampling circuit, the other end of the resistor R4 and a third pin of the reference voltage stabilizing chip U1 are connected with a grounding terminal.

2. The circuit for improving NTC sampling precision consistency according to claim 1, characterized in that: A capacitor C1 is connected in parallel between the second pin and the third pin of the reference voltage stabilizing chip U1.

3. The circuit for improving NTC sampling precision consistency according to claim 1, characterized in that: The resistor R3 has a resistance of 10K and an accuracy of ±1%.

4. The circuit for improving NTC sampling precision consistency according to claim 1, characterized in that: The resistor R4 has a resistance of 50K and an accuracy of ±1%.

5. The circuit for improving NTC sampling precision consistency according to claim 1, characterized in that: The reference voltage stabilizing chip U1 is of a type TL431.

6. The circuit for improving NTC sampling precision consistency according to claim 1, characterized in that: The NTC sampling circuit comprises a thermistor RT1, one end of the thermistor RT1 is connected with a resistor R1 and an ADC pin of a microprocessor respectively, the other end of the resistor R1 is connected with the second pin of the reference voltage stabilizing chip U1, the other end of the thermistor RT1 is connected with a grounding terminal.

7. The circuit for improving NTC sampling precision consistency according to claim 6, characterized in that: The thermistor RT1 has a resistance of 10K and an accuracy of ±1%.

8. The circuit for improving NTC sampling precision consistency according to claim 6, characterized in that: Capacitors C2 are connected in parallel on both ends of the thermistor RT1.

Images