Do You Really Want To Choose The PCB Design Magnetic Beads?
Whether to use patch beads or chip inductors in PCB design depends mainly on the application scenario. For example, chip inductors are required in resonant circuits; using chip beads is the best choice when eliminating unwanted EMI noise.
Some suggestions for correctly selecting the core of the magnetic bead in the PCB design:
1. what is the frequency range of the unwanted signal?
2. who is the noise source?
3. Is there room for placing magnetic beads on the PCB?
4. how much noise attenuation is needed
5. What are the environmental conditions (temperature, DC voltage, structural strength)?
6.What is the circuit and load impedance?
The first three can be judged by observing the impedance frequency curve provided by the manufacturer. All three curves in the impedance curve are very important, namely resistance, inductive reactance and total impedance. The total impedance is described by ZR22πfL()2+:=fL. From this curve, select the type of bead that has the largest impedance in the frequency range where attenuation is desired and the signal attenuation is as small as possible at low frequencies and DC. When the patch magnetic beads are under excessive DC voltage, the impedance characteristics will be affected. In addition, if the operating temperature rises too high, or the external magnetic field is too large, the impedance of the magnetic beads will be adversely affected.
Application of chip beads and chip inductors:
Chip inductors: radio frequency (RF) and wireless communications, information technology equipment, radar detectors, automobiles, cellular phones, pagers, audio equipment, PDAs (personal digital assistants), wireless remote control systems and low-voltage power supply modules.
Patch magnetic beads: clock generation circuit, filtering between analog circuit and digital circuit, I/O input/output internal connector (such as serial port, parallel port, keyboard, mouse, long distance telecommunication, local area network), radio frequency (RF) circuit Between high-frequency conducted interference in the power supply circuit and EMI noise suppression in computers, computers, video recorders (VCRS), television systems, and mobile phones, and interference-prone logic devices.