CN108931315A - A kind of temperature measuring circuit based on NTC thermistor - Google Patents
A kind of temperature measuring circuit based on NTC thermistor Download PDFInfo
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Abstract
The present invention proposes that a kind of temperature measuring circuit based on NTC thermistor, reference voltage can guarantee that it is attained by higher Measurement Resolution in all temperature ranges according to the resistance value automatic adjusument of NTC thermistor；When increasing current-limiting resistance to reduce self-heating effect, temperature measurement accuracy and resolution ratio are unaffected；The current direction of thermistor is flowed through by the switching of two-way single pole double throw analog switch periods, substantially weaken the 1/f noise, offset drift and parasitic heat galvanic effect of temperature measuring circuit, the drift for slowing down thermistor resistance value ensure that the long-term measurement accuracy of temperature measuring circuit；Temperature measurement accuracy and long-term measurement stability are only dependent upon analog-digital converter itself and 1 precision resistance, are not influenced by reference voltage noise, temperature drift and time drift.
Description
Technical field
The invention belongs to oceanographic observation field, the one kind for especially relating to use when measurement ocean temperature is based on NTC heat
The temperature measuring circuit of quick resistance.
Background technique
Ocean temperature is to indicate a physical quantity of seawater thermodynamic status, and the size of ocean temperature and variation are restriction and shadow
An important factor for element distributions, evolution such as Xiangshui County's text, meteorological, chemistry and biology, as physical and chemical parameter most important in seawater, temperature
The measurement of degree is the most important thing of oceanographic hydrological observation.Scientific research of seas requires increasingly the measurement accuracy of ocean temperature
Height, modern marine Investigation requirements, ocean temperature reach ± 0.002 DEG C of measurement accuracy in -2~40 DEG C of range domestic demands.
Modern marine observation instrument such as thermohaline depth measuring instrument (CTD) etc. generallys use negative temperature coefficient when measuring ocean temperature
(NTC) thermistor is as temperature sensor.Temperature-resistance value of NTC thermistor is in non-linear relation, need to be together with when use
Measuring circuit is calibrated in high-precision thermostat bath together, after calibration, can achieve ± 0.001 DEG C of measurement accuracy.NTC heat
Main deficiency of the quick resistance in ocean temperature measurement application is (1) thermistor resistance value and temperature in non-linear relation, temperature
When spending lower, thermistor resistance value is big, and unit temperature change corresponding thermistor change in resistance it is larger, it is relatively easy to survey
Amount；When temperature is higher, thermistor resistance value is small, and unit temperature change corresponding thermistor change in resistance it is smaller, measurement
Difficulty is bigger, it is necessary to using the analog-digital converter of higher resolution, this often means that increasing power consumption and cost.(2) NTC heat is close
Resistance is larger, and when energization can generate self-heating, leads to thermometric error, and especially under deep sea low temperature environment, self-heating is produced
Raw measurement error is relatively bigger, it is necessary to which control flows through electric current within 50uA.
The conventional temperature measuring circuit based on NTC thermistor is classified from principle, mainly there is capacitor charging method, partial pressure
Method, Wheatstone bridge method, ratiometric method.Wherein capacitor charging method, partial pressure method principle on it is relatively simple, vulnerable to a reference source wave
Dynamic influence, precision is limited, is not widely used in ocean temperature measuring instrument.
Wheatstone bridge method principle is as shown in Figure 1, RTFor thermistor, electric bridge, ginseng are formed with precision resistance R1, R2, R3
It examines voltage to obtain from reference voltage, eliminates the influence of a reference source, main problem is not solving the problems, such as self-heating error,
And measurement accuracy is influenced by 3 precision resistances, temperature measurement accuracy is relatively low, it is difficult to reach 0.01 DEG C；
Proportion expression thermometry is widely applied circuit form in current ocean temperature measuring instrument both at home and abroad, base
Present principles are as shown in Fig. 2, the circuit passes through successively acquisition measuring resistance RSWith thermistor RTSignal, pass through ratiometric conversion
Mode calculates the resistance value of thermistor, therefore is not influenced by a reference source fluctuation.The measuring circuit increases R1, R2 two simultaneously
A current-limiting resistance, the problem of avoiding self-heating error.But it has 2 major defects: (1) increase current-limiting resistance after temperature signal compared with
It is small, need higher analog-to-digital conversion definition.(2) it needs analog-digital converter to provide 2 pairs of difference measurement channels, carries out 2 moduluses
Conversion, time of measuring double, and are unfavorable for fast temperature measurement.
Therefore, the conventional temperature measuring circuit based on NTC thermistor, has a disadvantage in that:
(1) it can not solve the problems, such as that temperature Measurement Resolution is relatively relatively low when high temperature；
(2) it can not solve the problems, such as that self-heating effect and temperature Measurement Resolution are conflicting, ordinary temperature measuring circuit is logical
It crosses and reduces reference voltage or increase the mode of current-limiting resistance to reduce self-heating effect, also imply that temperature signal becomes smaller, lead to temperature
Spend Measurement Resolution decline；
(3) measurement accuracy of temperature measurement and long-term measurement stability have gone out except the influence by analog-digital converter, also
It is influenced by the noise of a reference source and multiple precision resistances, temperature drift, time drift.
Summary of the invention
The present invention proposes a kind of temperature measuring circuit based on NTC thermistor, within the scope of total temperature greatly
Temperature measurement accuracy is promoted, measurement error is reduced.
In order to achieve the above objectives, the technical scheme of the present invention is realized as follows:
A kind of temperature measuring circuit based on NTC thermistor, including the thermistor R being sequentially connected in seriesT, precision standard electricity
Hinder RS, current-limiting resistance RLThe series circuit of composition；The 2.5V benchmark electricity that the series circuit is carried using analog-digital converter AD7124
Pressure, thermistor RTWith precision standard resistance RSSignal is connected to analog-digital converter to the sum of both end voltage as the reference voltage
AD7124 reference voltage input pin Vref+, Vref-, thermistor RTThermistor voltage signal be connected to analog-to-digital conversion
Differential Input pin AIN1, AIN2 of device AD7124.
Further, the 2.5V reference voltage accesses the series circuit by two-way single pole double throw analog switch U1,
The 2.5V reference voltage is connected on the common pin COM1 of two-way single pole double throw analog switch the first way switch of U1, U1 second
The common pin COM2 of way switch is grounded；The normally closed pin NC1 of the first way switch of the two-way single pole double throw analog switch U1
The thermistor R of the series circuit is all connected with the normally opened pin NO2 of the second way switchTSide, the two-way single-pole double throw mould
The normally opened pin NO1 of the first way switch and the normally closed pin NC2 of the second way switch of quasi- switch U1 connects the series circuit
Current-limiting resistance RLSide；Single-chip microcontroller controls switch control pin IN1, the IN2 switching of the two-way single pole double throw analog switch U1
The direction of double switch.
Further, the thermistor RTWith precision standard resistance RSThe reference voltage signal at both ends passes through two-way list
Dpdt double-pole double-throw (DPDT) analog switch U2 accesses analog-digital converter AD7124 reference voltage input pin；The thermistor RTEnd is connected to double
On the common pin COM1 of road single pole double throw analog switch the first way switch of U2, the precision standard resistance RSEnd is connected to two-way
On the common pin COM2 of single pole double throw analog switch the second way switch of U2；The first of the two-way single pole double throw analog switch U2
It is defeated that the normally closed pin NC1 of the way switch and normally opened pin NO2 of the second way switch connects analog-digital converter AD7124 reference voltage
Enter pin Vref+, the normally opened pin NO1 of the first way switch of the two-way single pole double throw analog switch U2 and the second way switch
Normally closed pin NC2 connects analog-digital converter AD7124 reference voltage input pin Vref-；Single-chip microcontroller controls the two-way hilted broadsword
The direction of switch control pin IN1, the IN2 switching double switch of double-throw analog switch U2.
Further, the reference voltage signal is in access analog-digital converter AD7124 reference voltage input pin Vref
+, before Vref-, the low-pass filter that is collectively constituted by resistance R1, resistance R2, capacitor C1, capacitor C2, capacitor C12, wherein electricity
Resistance R1 is arranged on the route of connection pin Vref+, and resistance R2 is arranged on the route of connection pin Vref-, capacitor C1 and electricity
It is in parallel with capacitor C12 after appearance C2 series connection, it accesses between input pin Vref+, Vref-；The company of the capacitor C1 and capacitor C2
Contact ground connection.
Further, the thermistor RTThermistor voltage signal access analog-digital converter AD7124 difference
Before input pin AIN1, AIN2, the low-pass filtering that is collectively constituted by resistance R3, resistance R4, capacitor C3, capacitor C4, capacitor C34
Device, wherein resistance R3 is arranged on the route of connection pin AIN1, and resistance R4 is arranged on the route of connection pin AIN2, electricity
It is in parallel with capacitor C34 after appearance C3 and capacitor C4 series connection, it accesses between input pin AIN1, AIN2；The capacitor C3 and capacitor
The tie point of C4 is grounded.
Compared with prior art, the present invention have it is following the utility model has the advantages that
(1) measuring circuit proposed by the present invention, reference voltage can according to the resistance value automatic adjusument of NTC thermistor,
Guarantee that it is attained by higher Measurement Resolution within the scope of ocean temperature；Using temperature measuring circuit proposed by the present invention
Afterwards, temperature measurement accuracy can be greatly promoted within the scope of total temperature, reduce measurement error；
(2) measuring circuit proposed by the present invention, increase current-limiting resistance to reduce self-heating effect when, temperature measurement accuracy and point
Resolution is unaffected, solves the problems, such as that self-heating effect and temperature Measurement Resolution are conflicting；Using temperature proposed by the present invention
After spending measuring circuit, can accurately measure the temperature of environment itself to the maximum extent, without by thermistor from thermal effect
The influence answered；
(3) measuring circuit proposed by the present invention flows through temperature-sensitive electricity by the switching of two-way single pole double throw analog switch periods
The current direction of resistance substantially weakens the 1/f noise, offset drift and parasitic heat galvanic effect of temperature measuring circuit, slows down
The drift of thermistor resistance value ensure that the long-term measurement accuracy of temperature measuring circuit；
(4) measuring circuit proposed by the present invention, temperature measurement accuracy and long-term measurement stability are only dependent upon analog-to-digital conversion
Device itself and 1 precision resistance, are not influenced by reference voltage noise, temperature drift and time drift；Temperature proposed by the present invention
Degree measuring circuit does not need precision voltage reference or current source, and only needs 1 precision resistance, it is only necessary to 1 pair of analog-digital converter
Difference measurement channel can save hardware cost compared to conventional temperature measuring circuit；
(5) compared to conventional proportional formula temperature measuring circuit, the temperature measuring circuit for inventing proposition only needs to carry out 1 mould
Number conversion, conversion time are reduced, and are conducive to fast temperature measurement.
Detailed description of the invention
Fig. 1 is Wheatstone bridge method temperature measuring principle schematic diagram in the prior art；
Fig. 2 is proportion expression temperature measuring circuit schematic diagram in the prior art；
Fig. 3 is the circuit diagram of the embodiment of the present invention；
Fig. 4 is resistance value-temperature relation figure of the thermistor of the embodiment of the present invention.
Specific embodiment
It should be noted that in the absence of conflict, the feature in embodiment and embodiment in the present invention can phase
Mutually combination.
Technical solution of the present invention is described in further detail with reference to the accompanying drawing:
A kind of temperature measuring circuit based on NTC thermistor proposed by the present invention, principle is as shown in figure 3, U1, U2 are double
Road single pole double throw analog switch TS3A24159, RTFor thermistor, RSFor precision standard resistance, RLFor current-limiting resistance, heat is prevented
Quick resistance self-heating.R1, C1, R2, C2, C12 collectively constitute the low-pass filter of reference voltage signal, filter out reference voltage signal
Common mode and differential mode noise, R3, C3, R4, C4, C34 collectively constitute the low-pass filter of thermistor voltage signal, filter out temperature-sensitive electricity
Hinder the common mode and differential mode noise of signal.In the circuit, reference voltage be designed as thermistor and standard resistor at two terminals voltage it
With, be connected to after reference voltage signal is low-pass filtered analog-digital converter AD7124 reference voltage input pin (Vref+,
Vref-), be connected to after thermistor voltage signal is low-pass filtered analog-digital converter AD7124 Differential Input pin (AIN1,
AIN2)。
The 2.5V reference voltage that temperature measuring circuit uses analog-digital converter AD7124 to carry, reference voltage are connected to U1 the
In the common pin 3 of one way switch, the common pin 9 of the second way switch of U1 is grounded.The switch control pin of single-chip microcontroller control U1
(4,8) switch the direction of double switch, when low level, reference voltage is loaded on the normally closed pin 5 of U1 by U1 common pin 3, electricity
Stream is grounded after flowing to U1 common pin 9 by the normally closed pin 7 of U1 after thermistor, precision standard resistance and current-limiting resistance；It is high
When level, reference voltage is loaded on the normally opened pin 2 of U1 by U1 common pin 3, and electric current passes through current-limiting resistance, precision standard resistance
After thermistor, it is grounded after flowing to U1 common pin 9 by the normally opened pin 10 of U1.Thermistor signal passes through RC low-pass filter
Analog-digital converter AD7124 difference measurement pin is accessed afterwards.
Reference voltage is derived from thermistor and standard resistor at two terminals, and reference voltage is still positive when to guarantee circuit commutation,
Using the direction of the 2nd two-way single pole double throw analog switch U2 synchronism switching switching reference voltage, the switch control pin of U2 (4,
8) it is equally controlled by single-chip microcontroller, when low level, " reference voltage+" is flowed on the normally closed pin 5 of U2 by U2 common pin 3, " with reference to electricity
Pressure-" is flowed on the normally closed pin 7 of U2 by U2 common pin 9；When high level, it is normal that " reference voltage+" by U2 common pin 3 flows to U2
It opens on pin 2, " reference voltage-" is flowed on the normally opened pin 10 of U2 by U2 common pin 9." reference voltage+", " reference voltage-"
Analog-digital converter AD7124 reference voltage pin is accessed after RC low-pass filter.
After analog-digital converter AD7124 setting enables input buffer, input impedance is very high, typical input current only 1nA
Rank, therefore the electric current of analog-digital converter input terminal absorption can be ignored, the electric current on thermistor, which is considered as, all flows through standard
Resistance, by circuit voltage divider principle:
Wherein, VRTFor thermistor voltage, VRSFor reference voltage, RTFor thermistor resistance value, RSFor measuring resistance resistance value.
From analog-digital converter realization principle, transformation result is the ratio of thermistor voltage and reference voltage:
Wherein, Code is analog-digital converter conversion value, and Gain is amplification factor (Gain=1), and N is analog-digital bit
(N=24).It may further derive thermistor computing the resistor value formula:
From calculation formula (1) it can be seen that reference voltage can be high according to the resistance value automatic adjusument of NTC thermistor
Wen Shi, thermistor resistance value become smaller, and reference voltage is accordingly reduced, and improve the Measurement Resolution under hot environment；When low temperature, heat
Quick resistance is larger, and reference voltage increases accordingly, and guarantees that it is attained by higher measurement in all temperature ranges and differentiates
Rate.
Do not occur current-limiting resistance R when can be seen that thermistor computing the resistor value from calculation formula (3)L, show to increase current limliting
When resistance is to reduce self-heating effect, the measurement accuracy and resolution ratio of thermistor resistance value are unaffected.
From calculation formula (3) as can be seen that the measurement accuracy of thermistor resistance value and long-term measurement stability only rely upon
Analog-digital converter itself (Code) and 1 measuring resistance (RS), independent of reference voltage, reference voltage is avoided from principle
Noise, temperature drift and time drift influence.
To reduce self-heating effect, the electric current flowed through in measuring circuit should be less than 50uA, and reference voltage should be greater than modulus and turn
The minimum input voltage of parallel operation AD7124 requires (1V), and therefore, measuring resistance, the value size of current-limiting resistance should meet two limits
Condition processed:
Wherein Vc is benchmark voltage 2.5v, and temperature-sensitive change in resistance range is about 5~25k Ω, to make electricity proposed by the present invention
Road obtains optimum measurement performance, and the value of measuring resistance should be the minimum value for meeting above-mentioned two condition, the value of current-limiting resistance
It should be the maximum value for meeting above-mentioned two condition.Calculus book circuit Plays resistance RSValue is 15k Ω, current-limiting resistance RLValue
For 30k Ω.In addition to except the reason of the analog-digital converter itself, the precision of the temperature measuring circuit only relies upon measuring resistance RSTemperature
Degree drift and long-time stability, it is only 0.1ppm/ DEG C (- 25-75 DEG C of environment) that we, which select temperature drift coefficient, long-time stability up to ±
Precision metallic foil (Bulk Metal) resistance of 0.005% (0.04W, 70 DEG C, 2000 hours) is as measuring resistance.
It after thermistor is encapsulated, is calibrated in High Accuracy Constant Temperature seawater slot together with measuring circuit, after calibration
Thermistor resistance value can be converted into temperature value.Constant temperature seawater slot uses the first-class platinum resistance and accurate survey Jing Guo measurement verification
Warm electric bridge is as temperature standard, thermal field uniformity and stability up to 0.0005 DEG C.It calibrates formula and uses the side Steinhart-Hart
The improved form of journey:
The measurement performance of the temperature measuring circuit based on NTC thermistor of proposition is now illustrated the present invention, Fig. 4 is allusion quotation
The resistance value of the thermistor of type-temperature relation figure, it can be seen from the figure that thermistor resistance value exponentially declines pass with temperature
System.When environment temperature is lower, thermistor resistance value is big, and the corresponding thermistor change in resistance of unit temperature variation is larger, phase
To easy measurement；When environment temperature is higher, thermistor resistance value is small, and unit temperature changes corresponding thermistor change in resistance
It is smaller, measurement accuracy is required higher.How measuring circuit guarantees Measurement Resolution under hot environment, is the difficulty of traditional circuit
Point.
The measurement performance of temperature measuring circuit proposed by the present invention based on NTC thermistor, as shown in table 1.It is arranged in table
Precision of A/D converter needed for distinguishing 0.001 DEG C of temperature change in the punishment of each temperature spot is gone out, theoretical calculation shows that the present invention mentions
Temperature measuring circuit out is owned by very high measurement performance under the premise of eliminating self-heating effect at each temperature spot, wherein
When 22500 Ω of thermistor, corresponding temperature is -2.046 DEG C, which only needs 16.4 precision of A/D converter that can divide
Discern 0.001 DEG C of temperature change, when 4000 Ω of thermistor, corresponding temperature is 40.296 DEG C, which only needs 17.4
Position precision of A/D converter can tell 0.001 DEG C of temperature change.Theoretical calculation shows the measuring circuit to analog-to-digital conversion
Device requirement is lower, sufficiently achieves very high measurement accuracy using common 18 analog-digital converters.
1 temperature measuring circuit measurement performance of table calculates table
The foregoing is merely illustrative of the preferred embodiments of the present invention, is not intended to limit the invention, all in essence of the invention
Within mind and principle, any modification, equivalent replacement, improvement and so on be should all be included in the protection scope of the present invention.
Claims (7)
1. a kind of temperature measuring circuit based on NTC thermistor, which is characterized in that including the thermistor R being sequentially connected in seriesT, essence
Data Encryption Standard resistance RS, current-limiting resistance RLThe series circuit of composition；The series circuit is carried using analog-digital converter AD7124
2.5V reference voltage, thermistor RTWith precision standard resistance RSSignal is connected to modulus to the sum of both end voltage as the reference voltage
Converter AD7124 reference voltage input pin Vref+, Vref-, thermistor RTThermistor voltage signal be connected to mould
Differential Input pin AIN1, AIN2 of number converter AD7124.
2. a kind of temperature measuring circuit based on NTC thermistor according to claim 1, which is characterized in that described
2.5V reference voltage accesses the series circuit by two-way single pole double throw analog switch U1, and the 2.5V reference voltage is connected to
On the common pin COM1 of two-way single pole double throw analog switch the first way switch of U1, the common pin COM2 of the second way switch of U1 is connect
Ground；The normally closed pin NC1 of the first way switch of the two-way single pole double throw analog switch U1 and the normally opened pin of the second way switch
NO2 connects the thermistor R of the series circuitTSide, the first way switch of the two-way single pole double throw analog switch U1
The normally closed pin NC2 of normally opened pin NO1 and the second way switch connects the current-limiting resistance R of the series circuitLSide；Single-chip microcontroller control
Make the direction of switch control pin IN1, the IN2 switching double switch of the two-way single pole double throw analog switch U1.
3. a kind of temperature measuring circuit based on NTC thermistor according to claim 1 or 2, which is characterized in that described
Thermistor RTWith precision standard resistance RSThe reference voltage signal at both ends accesses modulus by two-way single pole double throw analog switch U2
Converter AD7124 reference voltage input pin；The thermistor RTEnd is connected to two-way single pole double throw analog switch U2 first
On the common pin COM1 of way switch, the precision standard resistance RSEnd is connected to the second tunnel two-way single pole double throw analog switch U2
On the common pin COM2 of switch；The normally closed pin NC1 of the first way switch of the two-way single pole double throw analog switch U2 and
The normally opened pin NO2 of two-way switch connects analog-digital converter AD7124 reference voltage input pin Vref+, the two-way hilted broadsword
The normally opened pin NO1 of the first way switch of the double-throw analog switch U2 and normally closed pin NC2 of the second way switch connects modulus and turns
Parallel operation AD7124 reference voltage input pin Vref-；Single-chip microcontroller controls the switch control of the two-way single pole double throw analog switch U2
The direction of pin IN1, IN2 switching double switch processed.
4. a kind of temperature measuring circuit based on NTC thermistor according to claim 3, which is characterized in that the ginseng
Voltage signal is examined before accessing analog-digital converter AD7124 reference voltage input pin Vref+, Vref-, by resistance R1, resistance
The low-pass filter that R2, capacitor C1, capacitor C2, capacitor C12 are collectively constituted, wherein resistance R1 is arranged in connection pin Vref+'s
On route, resistance R2 be arranged in connection pin Vref- route on, capacitor C1 and capacitor C2 series connection after it is in parallel with capacitor C12, connect
Enter between input pin Vref+, Vref-；The tie point of the capacitor C1 and capacitor C2 is grounded.
5. a kind of temperature measuring circuit based on NTC thermistor according to claim 1, which is characterized in that the ginseng
Voltage signal is examined before accessing analog-digital converter AD7124 reference voltage input pin Vref+, Vref-, by resistance R1, resistance
The low-pass filter that R2, capacitor C1, capacitor C2, capacitor C12 are collectively constituted, wherein resistance R1 is arranged in connection pin Vref+'s
On route, resistance R2 be arranged in connection pin Vref- route on, capacitor C1 and capacitor C2 series connection after it is in parallel with capacitor C12, connect
Enter between input pin Vref+, Vref-；The tie point of the capacitor C1 and capacitor C2 is grounded.
6. a kind of according to claim 1,2,4,5 described in any item temperature measuring circuits based on NTC thermistor, feature
It is, the reference voltage signal passes through before accessing analog-digital converter AD7124 reference voltage input pin Vref+, Vref-
The low-pass filter that resistance R1, resistance R2, capacitor C1, capacitor C2, capacitor C12 are collectively constituted, wherein resistance R1 setting is connecting
On the route of pin Vref+, resistance R2 be arranged in connection pin Vref- route on, capacitor C1 and capacitor C2 series connection after with electricity
It is in parallel to hold C12, accesses between input pin Vref+, Vref-；The tie point of the capacitor C1 and capacitor C2 is grounded.The heat
Quick resistance RTThermistor voltage signal access analog-digital converter AD7124 Differential Input pin AIN1, AIN2 before, warp
Cross the low-pass filter that resistance R3, resistance R4, capacitor C3, capacitor C4, capacitor C34 are collectively constituted, wherein resistance R3 setting is even
On the route for meeting pin AIN1, resistance R4 be arranged in connection pin AIN2 route on, capacitor C3 and capacitor C4 series connection after with electricity
It is in parallel to hold C34, accesses between input pin AIN1, AIN2；The tie point of the capacitor C3 and capacitor C4 is grounded.
7. according to a kind of described in any item temperature measuring circuits based on NTC thermistor of claim 3, which is characterized in that
The reference voltage signal is before accessing analog-digital converter AD7124 reference voltage input pin Vref+, Vref-, by resistance
The low-pass filter that R1, resistance R2, capacitor C1, capacitor C2, capacitor C12 are collectively constituted, wherein resistance R1 setting is in connection pin
On the route of Vref+, resistance R2 be arranged in connection pin Vref- route on, capacitor C1 and capacitor C2 series connection after with capacitor C12
Parallel connection accesses between input pin Vref+, Vref-；The tie point of the capacitor C1 and capacitor C2 is grounded.The temperature-sensitive electricity
Hinder RTThermistor voltage signal access analog-digital converter AD7124 Differential Input pin AIN1, AIN2 before, by electricity
The low-pass filter that resistance R3, resistance R4, capacitor C3, capacitor C4, capacitor C34 are collectively constituted, wherein resistance R3 setting is drawn in connection
On the route of foot AIN1, resistance R4 be arranged in connection pin AIN2 route on, capacitor C3 and capacitor C4 series connection after with capacitor C34
Parallel connection accesses between input pin AIN1, AIN2；The tie point of the capacitor C3 and capacitor C4 is grounded.
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| CN201811172499.9A CN108931315A (en) | 2018-10-09 | 2018-10-09 | A kind of temperature measuring circuit based on NTC thermistor |
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| CN (1) | CN108931315A (en) |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN110068394A (en) * | 2019-04-08 | 2019-07-30 | 上海艾为电子技术股份有限公司 | A kind of chip temperature detection circuit and audio-frequency power amplifier |
| CN111351593A (en) * | 2018-12-20 | 2020-06-30 | 海鹰航空通用装备有限责任公司 | Unmanned aerial vehicle battery temperature detection system and method |
| CN112461391A (en) * | 2020-11-11 | 2021-03-09 | 杭州仰仪科技有限公司 | Multi-channel thermistor iterative temperature measurement system in lithium battery isothermal calorimeter |
| CN114624517A (en) * | 2022-03-09 | 2022-06-14 | 国家海洋技术中心 | General resistance, voltage and frequency signal acquisition module |
| WO2024001924A1 (en) * | 2022-06-30 | 2024-01-04 | 深圳市中兴微电子技术有限公司 | Temperature sensor, temperature sensor packaging method, and temperature measurement method |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN111351593A (en) * | 2018-12-20 | 2020-06-30 | 海鹰航空通用装备有限责任公司 | Unmanned aerial vehicle battery temperature detection system and method |
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