Ferrite beads - small tubes for emi-suppression.
Ferrite beads produced by Ferroxcube are applied in high-frequency interference suppression when switching transistors, diodes in power wires. When using such cores the pins of electronic components are threaded through the beads holes. Among possible applications is parasitic oscillation reduction when using diodes in down converter circuit. Tne input circuit has a parasitic inductance. As pn-junction is characterised by some capacity a diode can't immediately be closed. The input circuit has a stray inductance. That's why a parasitic oscillating counter together with capacity of pn-junction is being formed. In such a case the beads are directly threaded on diodes pins in order to reduce such oscillations. Sometimes ferrite beads are threaded on transistors pins. The Pin of a transistor gate in a ferrite tube forms inductance which prevents to a sharp increasing of gate current. In such a case the tube works both as resistor and emi suppressor.

Geometrical dimensions and characteristics

The choiсe of tube depends on components pins on which filter is to be fixed. The inside diameter (d, mm) is being chosen depending on pins diameter. The dimension between components pins creates limitations towards outside diameter D.

The structure of the ordering code

BD5,1/0,8/10-3S1
BD — core configuration
5,1/0,8/10 — core size (outside and inside diameters, height)
3S1 — tube material