{"id":33891,"date":"2022-01-30T08:51:40","date_gmt":"2022-01-30T13:51:40","guid":{"rendered":"https:\/\/workbench.a2hosted.com\/fair-rite\/?page_id=33891"},"modified":"2022-06-07T05:34:26","modified_gmt":"2022-06-07T09:34:26","slug":"general-considerations-suppression","status":"publish","type":"page","link":"https:\/\/workbench.a2hosted.com\/fair-rite\/general-considerations-suppression\/","title":{"rendered":"General Considerations"},"content":{"rendered":"

GENERAL CONSIDERATIONS<\/span><\/h1>\n<\/div>
<\/div><\/div><\/div><\/div><\/div>

The United States was one of the first countries to recognize the potential problems caused by electromagnetic pollution. As a result, the FCC was charged with the responsibility of promulgating rules and regulations to control and enforce limits on high frequency interference.<\/strong><\/span><\/p>\n

Figure 1 shows the current radiation limits as defined by FCC Rules Part 15, for class A (industrial) and class B (mass-market) equipment.<\/span><\/p>\n

Figure 1<\/b><\/span><\/p>\n

Conducted EMI can occur over a wide range of frequencies, from as low as 1MHz to several GHz. To provide protection over such a wide frequency range a number of ferrite material are available. Figure 2 shows the suppression range of each of Fair-Rite Products suppression ferrite<\/span><\/p>\n\n\n\n\n\n\n\n\n\n\n
Material<\/b><\/span><\/td>\nOptimal Suppression Range<\/b><\/span><\/td>\nComments<\/b><\/span><\/td>\n<\/tr>\n
FR73<\/span><\/td>\n1 \u2013 25 MHz<\/span><\/td>\nBeads only<\/span><\/td>\n<\/tr>\n
FR75<\/span><\/td>\n1 \u2013 30 MHz<\/span><\/td>\nSnap-Its and solid cores<\/span><\/td>\n<\/tr>\n
FR15<\/span><\/td>\n10 \u2013 250MHz<\/span><\/td>\nCustomer specific applications<\/span><\/td>\n<\/tr>\n
FR31<\/span><\/td>\n1 \u2013 300 MHz<\/span><\/td>\nLarge parts only<\/span><\/td>\n<\/tr>\n
FR43<\/span><\/td>\n20 \u2013 300MHz<\/span><\/td>\nWide range of parts<\/span><\/td>\n<\/tr>\n
FR44<\/span><\/td>\n20 \u2013 300MHz<\/span><\/td>\nWide range of parts<\/span><\/td>\n<\/tr>\n
FR61<\/span><\/td>\n200+ MHz<\/span><\/td>\nWide range of parts<\/span><\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

Figure 2\u00a0<\/b><\/span><\/p>\n

Making the material selection is the first step in eliminating conducted EMI problems. To make this material selection it is imperative that the frequency of frequencies of the unwanted noise are known. This needn\u2019t be an exact figure; an approximation will be sufficient.<\/span><\/p>\n

Complex permeability will vary as a function of frequency. However, several environmental conditions will also affect these primary material parameters. The most significant ones are temperature and DC bias. In general, under conditions of high temperature and DC bias, ferrite\u2019s suppression performance will derate. In the materials section of our website, we have published impedance derating graphs for both of these conditions.<\/span><\/p>\n

The Curie temperature is the transition temperature above which the ferrite loses its magnetic properties. At this temperature the ferrite component is no longer performing its intended function. Once the material cools down below this temperature it will again perform as before. Fair-Rite Products publishes the Curie temperature of each of its materials under the materials section on our website.<\/span><\/p>\n

Fair-Rite Products manufactures three classes of ferrite materials, MnZn, NiZn, and MgZn. The manganese zinc materials have low resistivities whereas the nickel zinc and magnesium zinc materials have high resistivities. For applications that use non-insulated wires or for use as connector suppression plates, a ferrite material with the highest resistivity is recommended. Fair-Rite\u2019s FR44 material is an improved FR43 material by providing both increased resistivity and Curie temperature. Components in the FR44 NiZn material are catalog standard parts for connector plates and wound parts such as PC beads and wound beads.<\/span><\/p>\n<\/div>

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