1 semiconductor thermistor works
According to the temperature characteristics of thermistors can be divided into two categories, with the temperature rise resistance increases the positive temperature coefficient thermistor, otherwise negative temperature coefficient thermistor.
⑴ positive temperature coefficient of the working principle of thermistor
This kind of thermistor with barium titanate (BaTio3) as the basic material, and then add the appropriate amount of rare earth elements, the use of high-temperature ceramic sintering into Seoul. Barium titanate is an insulating material, but doped with an appropriate amount of rare earth elements such as lanthanum (La) and niobium (Nb), etc., into a semiconductor material, known as semiconductor barium titanate. It is a kind of polycrystalline material, crystal grains exist between the grain interface, for the conductive electrons, the intergranular interface is equivalent to a barrier. When the temperature is low, due to the role of the semiconductor barium titanate electric field, the conductive electrons can easily cross the barrier, so the resistance value is small; when the temperature rises to the Curie point temperature (ie, the critical temperature, Control point 'general barium titanate Curie point of 120 ℃), the internal electric field is destroyed, can not help the conductive electrons over the barrier, so the performance of the sharp increase in resistance. Because this kind of component has not reached the point before the resistance with temperature is very slow, with constant temperature, thermostat and automatic temperature control function, only fever, no red, no open flame, easy to burn, voltage, DC 3 ~ 440V Can be, long service life, very suitable for motor and other electrical devices overheating detection.
⑵ negative temperature coefficient of the working principle of thermistor
Negative temperature coefficient thermistor is based on manganese oxide, cobalt oxide, nickel oxide, copper oxide and alumina and other metal oxides as the main raw material, made of ceramic technology. These metal oxide materials are semiconducting, completely similar to germanium, silicon crystal materials, the body of the carrier (electrons and holes) the number of small, high resistance; temperature, the number of carriers in the body increased, the natural resistance Value is reduced. (300 ~ 600 ℃), high temperature (> 600 ℃) three kinds, with high sensitivity, good stability, fast response, long life , Low price advantages, widely used in the need for temperature measurement of temperature automatic control circuit, such as refrigerators, air conditioners, greenhouses and other temperature control system.
Thermistor and simple amplifier circuit can be combined to detect the temperature change of one thousandth of the time, so the thermometer and electronic instrument composition, to complete the high-precision temperature measurement. General use thermistor operating temperature of -55 ℃ ~ +315 ℃, special low temperature thermistor operating temperature below -55 ℃, up to -273 ℃.
2 thermistor model
I made the thermistor is the ministerial standard SJ1155-82 to develop models, composed of four parts.
The first part: the main said, with the letter 'M' that sensitive components.
Part 2: Category, with the letter 'Z' for positive temperature coefficient thermistor, or with letter 'F' for negative temperature coefficient thermistor.
The third part: use or feature, with a number (0-9) said. The general number '1' indicates normal use, '2' represents the regulator use (negative temperature coefficient thermistor), '3' represents the microwave measurement use (negative temperature coefficient thermistor), '4' (Negative temperature coefficient thermistor), '5' for temperature measurement, '6' for temperature control purposes, '7' for demagnetization (positive temperature coefficient thermistor), '8' for linear Temperature coefficient thermistor), '9' for constant temperature type (positive temperature coefficient thermistor), '0' for special type (negative temperature coefficient thermistor)
The fourth part: serial number, also by the number that, on behalf of specifications, performance.
Often manufacturers for the distinction between the special needs of this series of products, in the serial number after the 'derived serial number', by the letters, numbers and '-' combination.
Example: M Z 1 1
Serial number
General purpose
Positive temperature coefficient thermistor
Sensitive components
3 main parameters of the thermistor
The operating conditions of the various thermistors must be within the allowable range of their factory parameters. The main parameters of the thermistor are more than ten items: Nominal resistance value, Ambient temperature (maximum operating temperature), measuring power, rated power, nominal voltage (maximum operating voltage), operating current, temperature coefficient, material constant, time Constant and so on. Where the nominal resistance value is at 25 ℃ zero power when the resistance value, in fact there is always a certain error, should be within ± 10%. General thermistor operating temperature range is large, according to the need to choose from -55 ℃ to +515 ℃, it is worth noting that the maximum temperature of the different types of thermistor vary widely, such as MF11 sheet negative temperature coefficient of heat Sensitive resistance of +125 ℃, while the MF53-1 only +70 ℃, students should pay attention to the experiment (generally not more than 50 ℃).
According to the temperature characteristics of thermistors can be divided into two categories, with the temperature rise resistance increases the positive temperature coefficient thermistor, otherwise negative temperature coefficient thermistor.
⑴ positive temperature coefficient of the working principle of thermistor
This kind of thermistor with barium titanate (BaTio3) as the basic material, and then add the appropriate amount of rare earth elements, the use of high-temperature ceramic sintering into Seoul. Barium titanate is an insulating material, but doped with an appropriate amount of rare earth elements such as lanthanum (La) and niobium (Nb), etc., into a semiconductor material, known as semiconductor barium titanate. It is a kind of polycrystalline material, crystal grains exist between the grain interface, for the conductive electrons, the intergranular interface is equivalent to a barrier. When the temperature is low, due to the role of the semiconductor barium titanate electric field, the conductive electrons can easily cross the barrier, so the resistance value is small; when the temperature rises to the Curie point temperature (ie, the critical temperature, Control point 'general barium titanate Curie point of 120 ℃), the internal electric field is destroyed, can not help the conductive electrons over the barrier, so the performance of the sharp increase in resistance. Because this kind of component has not reached the point before the resistance with temperature is very slow, with constant temperature, thermostat and automatic temperature control function, only fever, no red, no open flame, easy to burn, voltage, DC 3 ~ 440V Can be, long service life, very suitable for motor and other electrical devices overheating detection.
⑵ negative temperature coefficient of the working principle of thermistor
Negative temperature coefficient thermistor is based on manganese oxide, cobalt oxide, nickel oxide, copper oxide and alumina and other metal oxides as the main raw material, made of ceramic technology. These metal oxide materials are semiconducting, completely similar to germanium, silicon crystal materials, the body of the carrier (electrons and holes) the number of small, high resistance; temperature, the number of carriers in the body increased, the natural resistance Value is reduced. (300 ~ 600 ℃), high temperature (> 600 ℃) three kinds, with high sensitivity, good stability, fast response, long life , Low price advantages, widely used in the need for temperature measurement of temperature automatic control circuit, such as refrigerators, air conditioners, greenhouses and other temperature control system.
Thermistor and simple amplifier circuit can be combined to detect the temperature change of one thousandth of the time, so the thermometer and electronic instrument composition, to complete the high-precision temperature measurement. General use thermistor operating temperature of -55 ℃ ~ +315 ℃, special low temperature thermistor operating temperature below -55 ℃, up to -273 ℃.
2 thermistor model
I made the thermistor is the ministerial standard SJ1155-82 to develop models, composed of four parts.
The first part: the main said, with the letter 'M' that sensitive components.
Part 2: Category, with the letter 'Z' for positive temperature coefficient thermistor, or with letter 'F' for negative temperature coefficient thermistor.
The third part: use or feature, with a number (0-9) said. The general number '1' indicates normal use, '2' represents the regulator use (negative temperature coefficient thermistor), '3' represents the microwave measurement use (negative temperature coefficient thermistor), '4' (Negative temperature coefficient thermistor), '5' for temperature measurement, '6' for temperature control purposes, '7' for demagnetization (positive temperature coefficient thermistor), '8' for linear Temperature coefficient thermistor), '9' for constant temperature type (positive temperature coefficient thermistor), '0' for special type (negative temperature coefficient thermistor)
The fourth part: serial number, also by the number that, on behalf of specifications, performance.
Often manufacturers for the distinction between the special needs of this series of products, in the serial number after the 'derived serial number', by the letters, numbers and '-' combination.
Example: M Z 1 1
Serial number
General purpose
Positive temperature coefficient thermistor
Sensitive components
3 main parameters of the thermistor
The operating conditions of the various thermistors must be within the allowable range of their factory parameters. The main parameters of the thermistor are more than ten items: Nominal resistance value, Ambient temperature (maximum operating temperature), measuring power, rated power, nominal voltage (maximum operating voltage), operating current, temperature coefficient, material constant, time Constant and so on. Where the nominal resistance value is at 25 ℃ zero power when the resistance value, in fact there is always a certain error, should be within ± 10%. General thermistor operating temperature range is large, according to the need to choose from -55 ℃ to +515 ℃, it is worth noting that the maximum temperature of the different types of thermistor vary widely, such as MF11 sheet negative temperature coefficient of heat Sensitive resistance of +125 ℃, while the MF53-1 only +70 ℃, students should pay attention to the experiment (generally not more than 50 ℃).
