TM
1．Noise Suppression Devices AMOBEADS TM
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, "AMOBEADSTM " and "SPIKE KILLERSTM ". AMOBEADSTM " deliver excellent noise suppression
results and are convenient to use by simply being slipped over the leads of the semiconductor device.
"AMOBEADSTM " are also available with a lead thru and in a surface mount configuration. "SPIKE KILLERSTM ",
which are larger in size than "AMOBEADSTM ", 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, "AMOBEADSTM " 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 "AMOBEADSTM " 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
With AMOBEADSTM
(AB4×2×8W)
Without Countermeasure
- 8 -
− 4 −
AB／LB Series
RoHS compliant products
Standard Specifications
AMOBEADSTM
W series
Finished Dimensions [mm]
O.D. max I. D. min H.T. max
4.0
1.5
4.5
Type No.
AB3X2X3W
Core Size [mm]＊1
O.D.
I. D.
H.T.
3.0
2.0
3.0
Total Flux＊2
φc[μWb] min
0.9
AL value＊3
L[μH] min
3.0
AB3X2X4.5W
4.0
1.5
6.0
3.0
2.0
4.5
1.3
5.0
AB4X2X4.5W
5.0
1.5
6.0
4.0
2.0
4.5
2.7
9.0
AB4X2X6W
5.0
1.5
7.5
4.0
2.0
6.0
3.6
12.0
AB4X2X8W
5.0
1.5
9.5
4.0
2.0
8.0
4.8
16.0
DY series (low price)
Type No.
Packing
Unit
PBT case
Blue
2,000
[pcs/box]
（Recommend for big demand, 10,000pcs/lot )
Finished Dimensions [mm]
Total Flux*7
φc[μWb]
Insulating
Cover
4.0±0.2
4.0±0.2
4.0±0.2
5.0+0.2/-0.3
5.95±0.2
0.9min
0.9min
1.3min
3.6min
0.45min
PBT
PBT
PBT
PBT
PBT
O.D.
AB2.8X4.5DY
AB3X2X3DY
AB3X2X4.5DY
AB4X2X6DY
AB5X4X3DY
Insulating
Cover
H.T.
5.7±0.3
4.2±0.3
5.7±0.3
7.2±0.3
4.2±0.3
Packing Unit
[pcs/bag］
Black
Black
Gray
Black
Black
10,000
10,000
10,000
5,000
5,000
※Inner diameter can pass through a 1.2Ｘ0.7mm lead.
However, Inner diameter of AB5x4x3DY can pass through a 2.5x0.7 mm lead.
W series
DY sereis
AMOBEADSTM with lead
Bulk type
Finished Dimensions [mm]
Type No.
*4
*2
B
*3
Current Total flux AL Value Insulating Packing
Unit
Cover
[A]
φc[μWb] L[μH]
B
D
E
F
LB4X2X8F 16.0max 4.2±0.5 14.0±1.0 φ1.25±0.1
（8.0）
LB4X2X8U 20.0max 4.0±0.5 5.0±1.0 φ1.25±0.1
4.8
min
16.0
min
B
F
PBT case 1,000
Black [pcs/box]
D
E
LB4X2X8F
Radial taping
ａ
Type No.
P [mm] Po [mm]
LB2.8X4.5U
12.7
Do [mm] a [mm]
12.7
φ4.0
9.0max
d [mm]
Current＊4
I [A]
φ0.8
(5)
Total Flux＊7 Packing
φc[μWb]
Unit
0.9min
D0
P0
Finished Dimensions [mm]
Lead
width
length
height width x thickness
＊4
＊2
Io
[A]
Total Flux
φc[μWb]
＊3
AL value Insulating
Cover
L[μH]
AB3X2X3SM
5.0±0.3
5.0±0.3
4.0±0.3
(1.8×0.35)
（6.0）
0.9 min
3.0
AB4X2X6SM
6.0±0.3
8.0±0.3
5.0±0.3
(1.8×0.52)
（9.0）
3.6 min
12.0
Packing
Unit
[pcs/reel]
2,000
LCP case
Black
1,000
Recommended Land Pattern (mm)
2.4
H
L
W
2.0
9.4
AB3X2X3SM
＊1
Reference Value ＊2 Minimum Guarantee on Measuring Condition : 50kHz、80A/m(sine wave), R.T.
＊3 Measuring Condition：50kHz, 1V, 1turn, R.T.
＊4 Typical Value, using a cross section of lead
＊5 Measuring Condition：100kHz, 80A/m
（sine wave), R.T. ＊6 Tolerance ±0.2［mm］
＊7 Converted from Inductance Value L1 at 1kHz、
100mA(sine wave)、R.T.
φｃ(μWb)＝0.282 x L1(μＨ)
TM
☆"AMOBEADS " sample kits are available. Please ask sales department.
TM
TM
☆"AMOBEADS " and "SPIKE KILLER " : Registered trademarks of TOSHIBA MATERIALS Co., Ltd.
TM
TM
☆"AMOBEADS " and "SPIKE KILLER " : Resistered in U.S.A., France, Germany, U.K., Japan.
- 9 -
− 5 −
2.4
3.3
14.7
AB4X2X6SM
F
LB4X2X8U
P
ｄ
3,000
[pcs/box]
SMD Type AMOBEADSTM
Type No.
D
E
Examples of Applied Circuits and their Characteristics
Application of Amorphous Noise Suppression Devices
AB
M
AB
AB
Chopper Converter
Control Circuit for Motor
AB
AB
AB
M
AB
Flyback Converter
AB
AB
Motor Driving Circuit
AB
100
Forward Converter
AB
AB4×2×8W
AB4×2×6W
AB4×2×4.5W
AL value
［μＨ]
10
AB
AB3×2×6W
AB3×2×4.5W
1
AB2.8×4.5DY
AB3×2×3W
Push-pull Converter
Characteristics (Typical value)
1k
100k
Frequency f [Hz]
1M
100
φ(t)/φ(25℃)
Pfe [kW/m3］
1000
100
500kH z
300kH z
50
200kH z
100kH z
Typical value
R.T.
Sine Wave
50kH z
1
0.01
10k
Frequency Characteristics of Inductance
10000
10
Typical Value
R.T.
0.1
0.1
0.
1
0
ΔB | [T]
20
40
60
80
100
120
Temperature [℃]
Flux(φ) Decline Ratio vs. Temperature
Coreloss Characteristic [AMOBEADSTM ]
- 10 -
− 6 −
TM
Effects of Noise Suppression by AMOBEADS TM
Spike Voltage Suppression
Without Countermeasure
Spike voltage can be reduced
and ringing phenomena can
also be prevented by AMOBEADS. Also Schottky barrier
diode (SBD) can be protected
from over voltage.
Diode Voltage
VD
10V/div
Frequency：500kHz
Output Voltage - Current
：5Ｖ-20Ａ
Output Noise Reduction
AMOBEADSTM "AB4×2×4.5Ｗ"
Diode Current
ID
5A/div
AMOBEADSTM "AB4×2×4.5Ｗ"
RC Snubber +Ferrite Beads
When the ferrite is replaced by
AMOBEADS at the secondary
output diode (FRD) of the
forward converter circuit, the
output noise can be tremendously reduced, not only the
noise peak level but also the
amplitude range.
Output Noise
VN
20mv/div
Frequency：150kHz
Output Voltage - Current
：15Ｖ-10Ａ
Ferrite Beads 4×2×4
AMOBEADSTM "AB4×2×4.5Ｗ"
Primary Surge Voltage
MOS-FET
Drain-Source
Voltage
VDS
200V/div
When the ferrite is replaced by
AMOBEADS at the secondary
output diode (SBD) of the
forward converter circuit, the
output noise and harmful
influence to the primary stage
can be
reduced. These
effects are based on the
inclination of the actual BH
curves between amorphous
and ferrite materials.
Frequency：250kHz
Output Voltage - Current
：5Ｖ-15Ａ
Output Noise
VN
50mv/div
Output Noise
B
H
Actual BH Curve
BH characteristics of Ferrite
- 11 -
− 7 −
BH characteristics of Amobeads
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