Core Materials for <1MHz

General Material Properties

Material Reference
Permeability
Powder Type Temp Coef of Perm
(+ppm/C°)
Density
gm/cm
Max Frequency
(MHz)
Relative Cost Color Code
Toroid
-2 1 Carbonyl Iron 95 N/A N/A N/A Red/Clear
-8 20 Carbonyl Iron 255 6.4 10 3.8 Yellow/Red
-14 10 Iron 150 5 45 2.2 Black/Red
​-18​ 35 Iron 385 6.5 5.0 3.3 Green/Red
-19 9 Iron 650 5.0 17 2.2 Red/Green
-26 8.5 Iron 95 5.0 55 3.6 Yellow/White
-30 9 Iron 255 5.0 50 3.0 Green/Gray
-34 35 Iron 150 6.5 5.0 3.1 Gray/Blue
-35 6 Iron 385 4.9 83 5.5 Yellow/Gray
-38 14 Iron 650 5.2 20 2.8 Gray/Black
-40 60 Iron 950 6.9 0.38 1.0 Green/Yellow
-45 100 Iron 1043 7.2 0.34 2.6 Black/Black
-52 75 Iron 650 7.0 0.59 1.1 Green/Blue

 


 

Material Magnetic Characteristics

Material Bsat (G) H (Oe) at
80% μi
%μi at
H=50 (Oe)
μ effective at
H=50 (Oe)

 

60 Hz/5000 G 10 kHz/500 G 100 kHz/140 G 1 MHz/40 G 10 MHz/15 G
-2 N/A N/A N/A N/A N/A N/A N/A N/A N/A
-8 17,500 221 97 19 45 59 31 21 107
-14 14,800 673 99 10 19 32 18 9 27
-18 17.600 101 92 32 45 59 31 21 107
-19 14,800 673 99 9 19 32 19 20 186
-26 14,800 1006 100 8 19 32 18 9 26
-30 14,800 778 100 9 19 32 18 9 27
-34 17,600 101 92 32 45 59 32 22 123
-35 14,600 2201 100 6 19 32 18 9 24
-38 15,200 406 99 14 19 32 18 11 49
-40 17,600 101 92 32 45 59 32 22 123
-45 14,600 2201 100 6 19 32 18 9 24
-52 15,200 406 99 14 19 32 18 11 49
  • ‐2 & ‐14 Materials: The low permeability of these materials will result in lower operating AC flux density than other materials with no additional gap‐loss. The ‐14 Material is similar to ‐2 Material with a higher permeability.
  • ‐8 Material: This material has low core loss and good linearity under high bias conditions. A good high frequency material, also the highest cost iron powder material.
  • ‐18 Material: This material has low core loss similar to the ‐8 Material with higher permeability and a lower cost. Good DC saturation characteristics.
  • ‐19 Material: An inexpensive alternate to the ‐18 Material with the same permeability and somewhat higher core losses.
  • ‐26 Material: A very popular material, it is a cost‐effective general purpose material that is useful in a wide variety of power conversion and line filter applications.
  • ‐30 Material: The good linearity, low cost and relatively low permeability of this material make a popular choice for high power UPS applications.
  • ‐34, ‐35 Materials: An inexpensive alternate to the ‐8 Material where high frequency core loss is not critical. Both ‐34 & ‐35 Materials have good linearity with high bias.
  • ‐38 Material: Similar to the ‐26 Material with higher permeability.
  • ‐40 Material: The least expensive iron powder material, characteristics similar to the ‐26 Material with a lower permeability. Most popular is large sizes.
  • ‐45 Material: The highest permeability iron powder material available. Consider as a high perm alternate to the ‐52 Material with slightly higher core losses.
  • ‐52 Material: This material has lower core losses at high frequency and the same permeability as the ‐26 Material. It is popular for high frequency choke designs and available in a wide variety of geometries.

 

Initial Permeability (µi) vs. DC
Magnetizing Force

Percent Initial Permeability (%µi) vs.
DC Magnetizing Force

Percent Initial Permeability (%µi) vs. Peak AC
Flux Frequency

Initial Permeability (µi) vs Frequency (Hz)

BH Curves

Material Frequency Range