Views:0 Author:Site Editor Publish Time: 2018-05-10 Origin:Site
Thermistor technical terms have many kinds of technical terms, so today, Ji Xu electronics here summing up the thermal resistance technical terms, to follow the footsteps of the small editor to understand it! Curie point, temperature compensation, inrush current, maximum working voltage
1. Curie point
When POSISTOR reaches a certain temperature, the resistance value is constant. Once the temperature is exceeded, the resistance will rise sharply. A point worthy of change in this resistance is called "Curie point".
2. Temperature compensation
It is caused by temperature changes that lead to errors in instruments and measuring devices. Special design is adopted to compensate accessory devices and electrical circuits. For components that change their characteristics due to temperature, they can be operated by inhibiting temperature changes.
When starting the switching power supply of an electronic device, a large current exceeds the rated current value.
4.Positive temperature coefficient thermistor
We say that although the temperature rises and the resistance increases, the positive temperature coefficient is positive, and the temperature characteristic of the PTC thermistor is a positive temperature coefficient. So we call it a positive temperature coefficient thermistor.
5. Negative temperature coefficient thermistor
We call the negative temperature coefficient as the temperature increases and the resistance decrease. The temperature characteristic of the JEC thermistor is a negative temperature coefficient. Therefore, the thermistor is a negative temperature coefficient thermistor
6. B constant
Using the resistance value at 2 points around the ambient temperature, the constant of resistance change is calculated according to the following formula.
B=In (R/R0) / (1/T-1T0)
R: the resistance value at ambient temperature of T (K) R0: the resistance value when the ambient temperature is T0 (K).
7. Maximum working voltage
It refers to the maximum voltage applied to POSISTOR in normal working temperature range.
8. Voltage resistance
The voltage that can withstand three minutes at 25 degrees of static air is voltage withstanding. The applied voltage starts from 0V and rises slowly to withstand voltage.
9. Heat dispersion coefficient (D)
The difference between the temperature difference between the heating body and the surrounding temperature is 1 C, the heat loss per unit time.
T: the temperature of the heating body
T0: ambient temperature
D: thermal divergence coefficient (W/ C)
This value is usually determined by the size, structure and material of the heater itself.
10. Thermal time constant (ysec)
When the temperature around POSISTOR moves from T0 to T1, the temperature difference is 0.632 times the time. Generally, the coefficient of thermal diffusing (W/ C) and the melting amount H are y=H/D. This is related to the dynamic characteristics.
11. Heating work point
POSISTOR the working point of the balance between self heating and external heating.
According to the current and voltage characteristics of POSISTOR, the maximum point of current is called current protection.
13.Change range of current protection
The current protection of POSISTOR varies with temperature, resistance, temperature and shape. The current field exceeding the upper limit of current protection is the field of work, and the current field below the lower limit is the field of non working current, and the current field between the upper and lower limits is called the range of current protection.
14. Working hours
The working time is the time required to reduce the inrush current flowing to POSISTOR to 1/2.