Noise Suppression Devices0 pages

2. Noise Suppression Devices

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.

Noise Suppression Device

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RC Snubber Magnetic Snubber

Basic Snubber Circuit Diagram

Bin

0.6

r

o.v.

-80 -AO

-0.4

-0.6

Amorphous

Ferrite

40 80

H [A/m]

(100 kHz. HT)

*i.»l*V>\«i

Noise Suppression Devices

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 was 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 Currant

1 A/div

Without Countermeasure

With AMOBEADS®

(AB4X2X8W)

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