title: COSEL Power Supply, Noise Filter 2025 Product Catalog

Summary

COSEL Power Supply, Noise Filter 2025 Product Catalog

4Noise Reduction1Input and Output Impedance and Filter CircuitThe input/output impedances of a noise source and a load will have various optimal filter circuits.General EMI filters take a configuration of a low pass filter that combines L and C. If the expected attenuation effect cannot be obtained, impedances of noise source and load may be the reasons.Table 4.1.1 Combinations of I/O Impedances and Optimal FiltersOutput impedance(Zo)HighLowZi: Input impedance(impedance of noise source)(Zi)Input impedanceHighLowNoise sourceEMIFilterZo: Output impedance(impedance of load)Figure 4.1.1 Input/output Impedances of an EMI Filter Circuit2EMI Filter Installation and OrientationGenerally, an EMI filter is placed in a way that the LINE terminal is connected to the input side, but it can also be used ina reverse configuration.However, it may end up producing a different attenuation effect.ConnectionEMIFilterLINELOADMotordriverMotorM100908070ConnectionTAC-30Level [dBμV]605040ConnectionEMIFilterLOADLINETAC-30MotordriverMotorM302010Connection00.1 1 10 100Frequency [MHz]Figure 4.2.1 Direction in which an EMI Filter Is Attached and ConnectedFigure 4.2.2 Example of Effed of Filter Orientation on NoiseIf the internal circuit consists of a symmetric EMI filter (one of the NBC series or TBC series), the direction in which thefilter is connected will not cause any difference in noise attenuation. But in the case of asymmetric ones, it may causedifference in the attenuation.CaseCaseLINELOADLINELOAD141425253636CYCYCYCYEMI/EMCFilterFigure 4.2.3 TAC Series Circuit Diagram(Circuit Is Asymmetric)Figure 4.2.4 TBC Series Circuit Diagram(Circuit Is Symmetric)CY: Line to ground capacitor: Mounting PlateTechnical Notes-12? 770 ?