CN217786379U - Temperature measurement circuit for small household appliances - Google Patents
Temperature measurement circuit for small household appliances Download PDFInfo
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- CN217786379U CN217786379U CN202222242241.XU CN202222242241U CN217786379U CN 217786379 U CN217786379 U CN 217786379U CN 202222242241 U CN202222242241 U CN 202222242241U CN 217786379 U CN217786379 U CN 217786379U
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Abstract
The utility model discloses a temperature measuring circuit for small household appliances, which belongs to the field of digital circuits and comprises a voltage conversion circuit, a resistance voltage dividing circuit, an operational amplifier circuit and a filtering overvoltage protection circuit; the voltage conversion circuit converts 5V voltage to obtain reference voltage 2.5V, the resistance voltage division circuit divides the reference voltage into two paths of voltage of comparison voltage U1 and sampling input voltage U2, the operational amplifier amplifying circuit amplifies the voltage difference value of the voltage U2 and the voltage U1, and the filtering overvoltage protection circuit is used for filtering interference and preventing overhigh instant peak voltage from being output to a rear-stage circuit to be damaged. The utility model has simple structure and fewer devices, and is possible for mass production of small household appliances; the final precision reaches 0.5 ℃, and the design requirement is completely met.
Description
Technical Field
The utility model relates to a digital circuit technical field, in particular to temperature measurement circuit for small household appliances.
Background
The PT1000 sensor is multipurpose for industrial control and automobile industry at present, a sampling circuit is complex, and for example, a three-wire constant current source driving circuit uses a double operational amplifier circuit.
The small household appliances use NTC sampling temperature more, but because some high-end small household appliance projects have the requirement of higher precision temperature sampling, if the beefsteak is baked, the temperature sampling circuit needs to be divided into several parts, a PT1000 sensor needs to be used, and the high-precision temperature sampling circuit is also more complicated.
SUMMERY OF THE UTILITY MODEL
An object of the utility model is to provide a temperature measurement circuit for small household appliances to when realizing the sampling of small household appliances high accuracy temperature, solve the complicated problem of sampling circuit structure.
In order to solve the technical problem, the utility model provides a temperature measuring circuit for small household appliances, which comprises a temperature measuring circuit and a temperature measuring circuit, wherein the temperature measuring circuit comprises a temperature measuring circuit and a temperature measuring circuit;
the voltage conversion circuit is used for converting the power supply voltage to obtain a reference voltage;
the resistance voltage division circuit divides the reference voltage into two paths of voltage of comparison voltage U1 and sampling input voltage U2;
the operational amplifier circuit amplifies the voltage difference value of the voltage U2 and the voltage U1;
and the filtering overvoltage protection circuit is used for filtering interference and preventing overhigh instantaneous peak voltage from being output to a post-stage circuit to cause the post-stage circuit to be damaged.
In one embodiment, the voltage conversion circuit comprises a current limiting resistor R9, a power supply chip AZ431AN and a filter capacitor C2; the first end of the power supply chip AZ431AN is connected with the first end of the filter capacitor C2, the second end of the power supply chip AZ431AN is connected with the first end of the current-limiting resistor R9, and the third end of the power supply chip AZ431AN is grounded. The second end of the current-limiting resistor R9 is connected with 5V power voltage, and the second end of the filter capacitor C2 is grounded; the 5V power supply voltage passes through the current limiting resistor R9, the power supply chip AZ431AN and the filter capacitor C2 to output stable 2.5V reference voltage to the resistor voltage dividing circuit.
In one embodiment, the resistive divider circuit includes a PT1000 sensor, resistors R1-R3; the first end of the PT1000 sensor is connected with 2.5V reference voltage through a resistor R1, and the second end of the PT1000 sensor is grounded; the first end of the resistor R2 is connected with 2.5V reference voltage, and the second end is grounded through a resistor R3;
the resistor R2 and the resistor R3 form a voltage division circuit, and the voltage between the resistor R2 and the resistor R3 is comparison voltage U1; the resistor R1 and the PT1000 sensor form a voltage division circuit, and the voltage between the PT1000 sensor and the resistor R1 is a sampling input voltage U2.
In one embodiment, the operational amplifier amplifying circuit comprises resistors R4-R7 and an operational amplifier U26B; the first end of the resistor R4 is connected with the comparison voltage U1, and the second end of the resistor R4 is connected with the negative input end of the operational amplifier U26B; the first end of the resistor R5 is connected with the sampling input voltage U2, and the second end of the resistor R is connected with the positive input end of the operational amplifier U26B; the resistor R7 is connected in parallel between the negative input end and the output end of the operational amplifier U26B, and the positive input end of the operational amplifier U26B is grounded through the resistor R6.
In one embodiment, the filtering overvoltage protection circuit comprises a capacitor C1, a resistor R8 and a packaging diode D1; a first end of the resistor R8 is connected with an output end of the operational amplifier U26B, and a second end of the resistor R is grounded through a capacitor C1; the first end of the packaging diode D1 is grounded, the second end is connected with 3.3V power voltage, and the third end is connected with the second end of the resistor R8.
In one embodiment, the op amp U26B selects the output voltage rail to rail.
The temperature measuring circuit for small household appliances provided by the utility model has the advantages of simple structure and fewer devices, and is possible for large-scale production of small household appliances; the utility model discloses a final precision reaches 0.5 ℃, accords with the design demand completely.
Drawings
Fig. 1 is a schematic diagram of a temperature measuring circuit for small household electrical appliances.
Detailed Description
The temperature measuring circuit for small household electrical appliances provided by the present invention is further described in detail with reference to the accompanying drawings and specific embodiments. The advantages and features of the present invention will become more apparent from the following description. It should be noted that the drawings are in simplified form and are not to precise scale, and are provided for convenience and clarity in order to facilitate the description of the embodiments of the present invention.
The utility model provides a temperature measuring circuit for small household appliances, which comprises a voltage conversion circuit 1, a resistance voltage dividing circuit 2, an operational amplifier circuit 3 and a filtering overvoltage protection circuit 4; the voltage conversion circuit 1 converts 5V mains voltage to obtain 2.5V reference voltage, the resistance bleeder circuit 2 divides the reference voltage into two way voltages of comparison voltage U1 and sampling input voltage U2, the operational amplifier circuit 3 amplifies the voltage difference of voltage U2 and U1, the filtering overvoltage protection circuit 4 is used for filtering interference, prevents that too high instantaneous peak voltage from exporting to the back stage circuit, makes its damage.
The voltage conversion circuit 1 comprises a current-limiting resistor R9, a power supply chip AZ431AN and a filter capacitor C2; the first end of the power supply chip AZ431AN is connected with the first end of the filter capacitor C2, the second end of the power supply chip AZ431AN is connected with the first end of the current limiting resistor R9, and the third end of the power supply chip AZ431AN is grounded. The second end of the current-limiting resistor R9 is connected with 5V power voltage, and the second end of the filter capacitor C2 is grounded. The 5V power supply voltage outputs a stable 2.5V reference voltage to the resistance voltage division circuit 2 through the current limiting resistor R9, the power supply chip AZ431AN and the filter capacitor C2.
The resistance voltage division circuit 2 comprises a PT1000 sensor and resistors R1-R3; the first end of the PT1000 sensor is connected with 2.5V reference voltage through a resistor R1, and the second end of the PT1000 sensor is grounded; the first end of the resistor R2 is connected with 2.5V reference voltage, and the second end is grounded through a resistor R3. The resistor R2 and the resistor R3 form a voltage division circuit, a comparison voltage U1 is calculated according to the characteristics of the PT1000 sensor and a temperature-resistance value curve and with reference to the requirement of the lowest temperature to be measured, and the comparison voltage U1 is the voltage between the resistor R2 and the resistor R3; considering power consumption, the current needs to be less than 1mA, and the method can be realized by selecting a proper resistance value. The resistors R1 and PT1000 sensor are combined into a voltage-dividing circuit, and the sampling input voltage U2 is the voltage between the PT1000 sensor and the resistor R1.
The operational amplifier amplifying circuit 3 comprises resistors R4-R7 and an operational amplifier U26B; the first end of the resistor R4 is connected with the comparison voltage U1, and the second end of the resistor R4 is connected with the negative input end of the operational amplifier U26B; the first end of the resistor R5 is connected with the sampling input voltage U2, and the second end is connected with the positive input end of the operational amplifier U26B; the resistor R7 is connected in parallel between the negative input end and the output end of the operational amplifier U26B, and the positive input end of the operational amplifier U26B is grounded through the resistor R6. The op amp U26B selects the output voltage rail to rail, i.e., the output voltage of the op amp approaches or reaches the supply voltage of the op amp.
The filtering overvoltage protection circuit 4 comprises a capacitor C1, a resistor R8 and a packaging diode D1, and a signal V _ SENSOR _ C is a voltage signal of the SENSOR PT1000 after sampling and operational amplification; a first end of the resistor R8 is connected with an output end of the operational amplifier U26B, and a second end of the resistor R is grounded through a capacitor C1; the first end of the packaging diode D1 is grounded, the second end is connected with 3.3V power voltage, and the third end is connected with the second end of the resistor R8. With reference to fig. 1, the packaged diode D1 includes a first diode and a second diode connected in series, and a cathode of the first diode is connected to an anode of the second diode. A first end of the packaged diode D1 is an anode of the first diode, a second end of the packaged diode D1 is a cathode of the second diode, and a third end of the packaged diode D1 is a cathode of the first diode (or an anode of the second diode).
When the temperature to be measured rises, the resistance value of the PT1000 sensor is increased, the sampling input voltage U2 is increased, the voltage difference between the sampling input voltage U2 and the comparison voltage U1 is amplified by an operational amplifier circuit composed of a resistor R4, a resistor R7, a resistor R5, a resistor R6 and an operational amplifier U26B, and then enters a single chip microcomputer for data acquisition through a filtering overvoltage protection circuit composed of a resistor R8, a capacitor C1 and a packaging diode D1. The resistance values of the resistor R4, the resistor R7, the resistor R5 and the resistor R6 are selected to determine the amplification factor of the circuit, the amplification factor needs to be determined according to the sampling temperature range and the sampling voltage range of the single chip microcomputer, and the operational amplifier U26B needs to select from rail to rail, so that the sampling voltage range is favorably improved, and the sampling resolution is improved.
The above description is only for the preferred embodiment of the present invention and is not intended to limit the scope of the present invention, and any modification and modification made by those skilled in the art according to the above disclosure are all within the scope of the claims.
Claims (6)
1. A temperature measuring circuit for small household appliances is characterized by comprising a temperature measuring circuit;
the voltage conversion circuit is used for converting the power supply voltage to obtain a reference voltage;
the resistance voltage division circuit divides the reference voltage into two paths of voltage, namely comparison voltage U1 and sampling input voltage U2;
the operational amplifier circuit amplifies the voltage difference value of the voltage U2 and the voltage U1;
and the filtering overvoltage protection circuit is used for filtering interference and preventing overhigh instantaneous peak voltage from being output to a post-stage circuit to cause the post-stage circuit to be damaged.
2. The temperature measuring circuit for the small household appliances according to claim 1, wherein the voltage converting circuit comprises a current limiting resistor R9, a power chip AZ431AN and a filter capacitor C2; the first end of the power supply chip AZ431AN is connected with the first end of the filter capacitor C2, the second end of the power supply chip AZ431AN is connected with the first end of the current-limiting resistor R9, the third end of the power supply chip AZ431AN is grounded, the second end of the current-limiting resistor R9 is connected with 5V power supply voltage, and the second end of the filter capacitor C2 is grounded; the 5V power supply voltage passes through the current limiting resistor R9, the power supply chip AZ431AN and the filter capacitor C2 to output stable 2.5V reference voltage to the resistor voltage dividing circuit.
3. The temperature measuring circuit for small household electrical appliances according to claim 1, wherein the resistance voltage dividing circuit comprises a PT1000 sensor, resistors R1 to R3; the first end of the PT1000 sensor is connected with 2.5V reference voltage through a resistor R1, and the second end of the PT1000 sensor is grounded; the first end of the resistor R2 is connected with 2.5V reference voltage, and the second end is grounded through a resistor R3;
the resistor R2 and the resistor R3 form a voltage division circuit, and the voltage between the resistor R2 and the resistor R3 is comparison voltage U1; the resistors R1 and the PT1000 sensor form a voltage division circuit, and the voltage between the PT1000 sensor and the resistor R1 is sampling input voltage U2.
4. The temperature measuring circuit for the small household appliances according to claim 1, wherein the operational amplifier circuit comprises resistors R4 to R7 and an operational amplifier U26B; the first end of the resistor R4 is connected with the comparison voltage U1, and the second end of the resistor R4 is connected with the negative input end of the operational amplifier U26B; the first end of the resistor R5 is connected with the sampling input voltage U2, and the second end of the resistor R is connected with the positive input end of the operational amplifier U26B; the resistor R7 is connected in parallel between the negative input end and the output end of the operational amplifier U26B, and the positive input end of the operational amplifier U26B is grounded through the resistor R6.
5. The temperature measuring circuit for the small household appliances according to claim 1, wherein the filtering overvoltage protection circuit comprises a capacitor C1, a resistor R8 and a package diode D1; a first end of the resistor R8 is connected with an output end of the operational amplifier U26B, and a second end of the resistor R is grounded through a capacitor C1; the first end of the packaging diode D1 is grounded, the second end is connected with 3.3V power voltage, and the third end is connected with the second end of the resistor R8.
6. The temperature measurement circuit for small household appliances according to claim 4, wherein the operational amplifier U26B selects an output voltage rail to rail.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202222242241.XU CN217786379U (en) | 2022-08-24 | 2022-08-24 | Temperature measurement circuit for small household appliances |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202222242241.XU CN217786379U (en) | 2022-08-24 | 2022-08-24 | Temperature measurement circuit for small household appliances |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN217786379U true CN217786379U (en) | 2022-11-11 |
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Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202222242241.XU Active CN217786379U (en) | 2022-08-24 | 2022-08-24 | Temperature measurement circuit for small household appliances |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN217786379U (en) |
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2022
- 2022-08-24 CN CN202222242241.XU patent/CN217786379U/en active Active
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