Beads and inductors
General habits: a wire material therethrough called bead wire in the through hole of the magnetic material on the inductance of winding is called a
There are three differences:
1, bead itself is theoretically energy, an inductor is theoretically non-dissipative.
2, the inductor is not closed magnetic material, typically a bar magnet structure, magnetic flux passes through a portion of magnetic material (magnetic bar), some of it is in the air; Magnets and magnetic beads is closed, the typical structure of a magnetic ring, almost all magnetic force lines in the ring, does not emit into the air.
3, the magnetic field strength changing, there will be a current is induced in the magnetic material, and the coefficient selection of high hysteresis magnetic material of low resistivity will be able to convert the high-frequency energy into heat energy, and thus consumed. And the inductor on the contrary, to choose magnetics low hysteresis coefficient and high resistivity, so as to render consistent inductance inductance values within the entire frequency band.
The inductor is a basic electronic components, collectively it belongs. Similarly, also collectively resistance, but there are many internal classification, such as classified by power (high power, low power resistors ), use classification by function ( pull-up resistor , the load resistor , thermistor). Beads inductance and a special effect (specific to suppress high frequency noise spikes and interference signal lines, power lines, also capable of absorbing the electrostatic pulses), it has a high resistivity and magnetic permeability, and a frequency characteristic different from ordinary inductors, only the high-frequency signal has a strong ability to inhibit, while the low frequency, the resistance is much smaller than the inductance, magnetic beads are generally at XXX MHz / XXX Europe (special attention, beads units ohm! inductance while the unit is Henry , completely different) represented in the form, which is also different inductance representation (general standard inductance inductance value). Functionally, the inductor used in many aspects of the power filter, are energy storage element, the spacer element belonging to beads, for more signal circuit.
Simply put, you can say, is a bead inductors, but can not say that is the inductance beads, range includes completely different.
Beads
beads (ferrite bead) materials are iron or iron-nickel alloy, magnesium, these materials have a high electrical resistivity and magnetic permeability at high frequencies and high impedance, the capacitance between the inductor minimizes . Beads usually only suitable for high frequency circuit, because at low frequencies, which are substantially retain characteristic of the inductance of the complete (with resistive and reactive components), thus resulting in a slight loss of the line. While at high frequencies, which has a reactive component substantially only (jωL), and the resistance component increases with frequency increase. Unlike some RF circuit, PLL, oscillation circuit, a memory circuit containing ultra-high frequency (DDR, SDRAM, RAMBUS, etc.) need to increase the power input portion beads.
Indeed, the beads are high-frequency attenuator of RF energy. In fact, the beads may be considered as a resistor in parallel with an inductor. At low frequencies, the inductor resistance is "short circuit", the current flowing to the inductor; at high frequencies, the high inductance of the inductor forces the current flows to the resistor. Essentially, the magnetic beads is a "dissipative device (dissipative device)", which high frequency energy is converted into heat. Thus, the performance, which can only be interpreted as a resistance, inductance instead.
Inductance of
the inductor is an energy storage element, used for power supply filtering circuit, the LC oscillator circuit, low-frequency filter circuit, the frequency range of application rarely exceeds 50MHz. For the inductor, and its inductance is proportional to the frequency of. This may be by the formula: XL = 2πfL be described, wherein XL is the inductive reactance (the unit is Ω). For example: An ideal 10mH inductor, at 10kHz, inductance is 628Ω; at 100MHz, increased 6.2MΩ. Therefore, when 100MHz, this inductance can be regarded as open (open circuit). When 100MHz, so that if a signal through this inductance will cause the signal quality decreases.
Zero ohm
refers to resistance of the resistor is zero. Circuit board design can not be connected to two points in the printed circuit, with the front often connected across the line, which is often seen in normal plate, in order to allow automatic placement machine and the automatic plug work, instead of across the line with zero resistance.