1. Inductance is an energy storage element, while magnetic beads serve as energy conversion (consumption) elements.
2. Inductors are predominantly utilized in power filter circuits, primarily aimed at suppressing conducted interference, whereas magnetic beads find their application in signal circuits, chiefly for EMI mitigation.
3. Magnetic beads are employed to absorb ultra-high frequency signals. For instance, certain RF circuits, PLL, oscillator circuits, and ultra-high frequency memory circuits (DDR, SDRAM, RAMBUS, etc.) necessitate the addition of magnetic beads to the power input section.
4. Inductors represent a type of energy storage element, utilized in LC oscillator circuits, medium and low-frequency filter circuits, etc., with their operational frequency rarely exceeding 50MHz.
1.1. The unit of the magnetic bead is ohm, not Hunter. This point must be given special attention. It is nominally based on the impedance it generates at a certain frequency; hence, the unit of impedance is also ohms. The datasheet of the magnetic beads generally provides frequency and impedance characteristic curves, typically based on 100MHz, such as 1000Ω at 100MHz, indicating that the impedance of the magnetic beads is equivalent to 1000 ohms at a frequency of 100MHz.
1.2. Ordinary filters are composed of lossless reactive components. Their role in the line is to reflect the stopband frequency back to the signal source, making them also known as reflection filters. When the reflection filter does not match the impedance of the signal source, a portion of the energy will be reflected back to the signal source, resulting in an increase in interference level. To address this, a ferrite magnetic ring or a magnetic bead sleeve can be used on the incoming line of the filter. The eddy current loss of the nuisance ring or magnetic bead to the high-frequency signal is utilized to convert the high-frequency component into heat loss. Therefore, the magnetic ring and the magnetic beads effectively absorb high-frequency components, hence sometimes referred to as absorption filters.
2. Some suggestions for correctly choosing the core of magnetic beads:
The first three can be determined by observing the impedance frequency curve provided by the manufacturer. Three curves are crucial in the impedance curve: resistance, inductance, and total impedance. Total impedance is described by the equation Z = √(R^2 + (2πfL)^2). Through this curve, select the magnetic bead model with the highest impedance in the frequency range where noise is to be attenuated while ensuring minimal signal attenuation at low frequencies. The impedance characteristics of SMD magnetic beads can be affected by excessive DC voltage. Additionally, if the operating temperature rises excessively or if the external magnetic field is too strong, the impedance of the magnetic beads may be adversely affected.
3. Application of magnetic beads and inductance:
– SMD inductance: Radio frequency (RF) and wireless communications, information technology equipment, radar detectors, automobiles, cellular phones, searchers, audio equipment, PDAs (personal digital assistants), wireless remote control systems, and low-voltage power supply modules.
– SMD magnetic beads: Clock generation circuit, filtering between analog and digital circuits, I/O input/output internal connectors (such as serial ports, parallel ports, keyboards, mice, long-distance telecommunications, local area networks), radio frequency (RF) circuits between logic devices susceptible to interference, power supply circuit filters for high-frequency conduction interference, and suppression of EMI noise in computers, video recorders (VCRs), TV systems, and mobile phones.
2. Inductors are predominantly utilized in power filter circuits, primarily aimed at suppressing conducted interference, whereas magnetic beads find their application in signal circuits, chiefly for EMI mitigation.
3. Magnetic beads are employed to absorb ultra-high frequency signals. For instance, certain RF circuits, PLL, oscillator circuits, and ultra-high frequency memory circuits (DDR, SDRAM, RAMBUS, etc.) necessitate the addition of magnetic beads to the power input section.
4. Inductors represent a type of energy storage element, utilized in LC oscillator circuits, medium and low-frequency filter circuits, etc., with their operational frequency rarely exceeding 50MHz.
1.1. The unit of the magnetic bead is ohm, not Hunter. This point must be given special attention. It is nominally based on the impedance it generates at a certain frequency; hence, the unit of impedance is also ohms. The datasheet of the magnetic beads generally provides frequency and impedance characteristic curves, typically based on 100MHz, such as 1000Ω at 100MHz, indicating that the impedance of the magnetic beads is equivalent to 1000 ohms at a frequency of 100MHz.
1.2. Ordinary filters are composed of lossless reactive components. Their role in the line is to reflect the stopband frequency back to the signal source, making them also known as reflection filters. When the reflection filter does not match the impedance of the signal source, a portion of the energy will be reflected back to the signal source, resulting in an increase in interference level. To address this, a ferrite magnetic ring or a magnetic bead sleeve can be used on the incoming line of the filter. The eddy current loss of the nuisance ring or magnetic bead to the high-frequency signal is utilized to convert the high-frequency component into heat loss. Therefore, the magnetic ring and the magnetic beads effectively absorb high-frequency components, hence sometimes referred to as absorption filters.
2. Some suggestions for correctly choosing the core of magnetic beads:
The first three can be determined by observing the impedance frequency curve provided by the manufacturer. Three curves are crucial in the impedance curve: resistance, inductance, and total impedance. Total impedance is described by the equation Z = √(R^2 + (2πfL)^2). Through this curve, select the magnetic bead model with the highest impedance in the frequency range where noise is to be attenuated while ensuring minimal signal attenuation at low frequencies. The impedance characteristics of SMD magnetic beads can be affected by excessive DC voltage. Additionally, if the operating temperature rises excessively or if the external magnetic field is too strong, the impedance of the magnetic beads may be adversely affected.
3. Application of magnetic beads and inductance:
– SMD inductance: Radio frequency (RF) and wireless communications, information technology equipment, radar detectors, automobiles, cellular phones, searchers, audio equipment, PDAs (personal digital assistants), wireless remote control systems, and low-voltage power supply modules.
– SMD magnetic beads: Clock generation circuit, filtering between analog and digital circuits, I/O input/output internal connectors (such as serial ports, parallel ports, keyboards, mice, long-distance telecommunications, local area networks), radio frequency (RF) circuits between logic devices susceptible to interference, power supply circuit filters for high-frequency conduction interference, and suppression of EMI noise in computers, video recorders (VCRs), TV systems, and mobile phones.
