Electronic – How to check ferrite beads

ferrite-beadinductanceinductance-measurementinductor

I faced with a problem of checking ferrite bead with parameters:

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The measurements for two reels of this component have difference in Resistance and inductance:

Reel 1: Resistance: 170 mOhm, Inductance: 2.5 uH (10kHz)

Reel 2: Resistance: 460 mOhm, Inductance: 9.9 uH (10kHz)

Can You assist with next questions:

  1. Why there are such difference in Resistance and Inductance between two components from different reels? Does this difference matter?
  2. Why in spec don’t specified inductance?
  3. Why on Characteristic Curve no value of impedance 1000 Ohm? Because I guess that curve for Z should be with Impedance value near 1000 Ohm.

Characteristic Curve

Best Answer

In specification defined only maximum value of DCR: 550 mOhm. So, does the difference in DCR matter?

That totally depends on your target circuit and what it maximum DCR it can live with to function/perform to expectations.

Why in spec don’t specified inductance and on Characteristic Curve no value of impedance 1000 Ohm?

Sure it's there - see the "X" curve - that is the inductive reactance versus frequency.

Also why can exist such difference between two components from different reels?

The spec says maximum DCR of 0.55 ohms so why shouldn't you expect a typical DCR range from 0.17 to 0.46 ohms? If you looked at a MOSFET spec for its on-resistance I bet you could get a up to a 3 to 1 variation between min and max.

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