2.
Noise Suppression Devices AMOBEADS
An amorphous noise suppression device is unique and completely different from conventional noise
filters. Conventional noise prevention products focus on somehow minimizing the noise after it's been
created, by typically trying to absorb the noise, and so their effectiveness in noise reduction is directly
influenced by frequency of the circuit. Amorphous noise suppressing devices, on the other hand, focus
on the source of the noise and work to prevent or minimize the noise before it has a chance to develop.
The source of the electronic circuit noise is the rapid change of current or voltage, and the
effectiveness of the amorphous cores in eliminating this noise is independent of frequency.
An amorphous noise suppression device is a product that takes full advantage of the unique magnetic
characteristics of the cobalt based amorphous alloy. Toshiba Materials offers two noise suppression
devices, "AMOBEADS " and "SPIKE KILLERS ". AMOBEADS " deliver excellent noise suppression
results and are convenient to use by simply being slipped over the leads of the semiconductor device.
"AMOBEADS " are also available with a lead thru and in a surface mount configuration. "SPIKE KILLERS ", which
are larger in size than "AMOBEADS ", most often are wire wound and are effective in eliminating or
minimizing higher noise levels.
C
Noise Suppression Device
R
AB
RC Snubber
Magnetic Snubber
Basic Snubber Circuit Diagram
B[T]
0.6
Amorphous
0.4
Ferrite
0.2
-80
-40
0
-0.2
40
80
H [A/m]
-0.4
-0.6
(100 kHz, RT)
B-H Curve(typical)
Example for Noise Suppressing Effect (Chopper Converter)
With an excellent saturable characteristic, "AMOBEADS " suppress the reverse recovery current of
the diode and decrease the noise that is occurring. When the current for diode reverses and tries to
go into the recovery condition, the "AMOBEADS " displays a large inductance and oppose the
generation of the recovery current. In this instance, a soft recovery is possible for core material with a
smaller coercive force.
Output Noise
Diode Current
1A/div
Without Countermeasure
With AMOBEADS
(AB4×2×8W)
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