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Thermistor, NTC thermistor, NTC temperature sensor
Thermistor input current impedance and frequency.
The input current determines the required wire diameter of the winding. In calculating the diameter, the current density is usually taken as 400A / cm3. However, this value must change with the inductor temperature rise. Normally, the windings work with a single wire, which reduces high-frequency noise and skin effect losses.
The impedance of the common-mode inductor is given a minimum value for the frequency conditions given. The linear resistance in series provides the usual required noise reduction. But unfortunately, there are quite a few people who know linear impedance, so designers often test common-mode inductors with 50-W linear impedance stabilizers and have gradually become a standard method of testing the performance of common mode inductors. However, the results obtained are often quite different from the actual ones. In fact, common mode inductance at normal corner frequencies will first produce a -6dB attenuation per octave (corner frequency is -3dB for common mode inductors) This corner frequency is typically low so that inductive reactance provides impedance. So the inductance can be expressed by the following formula:
Ls = Xx / 2πf
Inductance we all know, but it is worth mentioning that the design must pay attention to the core, core material and the required number of turns.
First of all, the first step in the design is the selection of the core type. If there is a specified inductance space, we select the suitable core type according to this space. If not specified,
The second step is to calculate the maximum number of turns around the core. Common mode inductors have two windings, usually a single layer, and each winding is located on each side of the core, the two windings to be separated by a certain distance. Double and stacked windings are also used sporadically, but this practice increases the distributed capacitance of the windings and reduces the high frequency performance of the inductor. Since the diameter of the copper wire is determined by the magnitude of the linear current, the inner circumference can be calculated from the inner radius of the core minus the radius of the copper wire. So the maximum number of turns can be insulated copper wire plus the diameter and the circumference of each winding to calculate.
Shi Heng Group is a research and development, production thermistor, sales of private technology enterprises, the full range of products NTC thermistor, NTC temperature sensor, PTC thermistor and zinc oxide varistors and other sensitive components, Among them NTC thermistor series covers surge suppression, temperature compensation, precision temperature measurement, temperature control and other applications, including NTC thermistor all varieties and specifications, is the largest manufacturer of NTC thermistor.
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