title: COSEL Power Supply, Noise Filter 2025 Product Catalog

Summary

COSEL Power Supply, Noise Filter 2025 Product Catalog

2Selection of EMI Filters6 DC Resistance8CircuitryDC resistance is a resistance value between the inputand output of an EMI filter (the sum of resistancevalues for both directions).It is mostly accounted for with the coil resistancesbut also includes connections between the coils andterminals.The voltage drop caused by an EMI filter is representedwith the following expression:Voltage drop = DC resistance x Load currentNote that specifications for some products definevoltage drops when rated current is carried, instead ofresistance values.7Temperature/Humiditya. Operating temperatureThis is the range of ambient temperatures for which theproduct’s usage is guaranteed.If an ambient temperature is high, the load current needsto be derated.b. Operating humidityThis is the range of ambient humidities for which theproduct’s usage is guaranteed.It assumes no condensation.c. Storage temperature and humidityThe specified ranges of ambient temperatures andhumidities that EMI filters in an unenergized state canbe stored without deteriorating performance.Nocondensation is assumed for the storage humidity.The following represents examples of EMI filter circuitstructures.a. Single-phase 1-stage filterCase1L3LINECYRCXCXLOAD2CY4Figure 2.8.1 Circuit Structure Example ofa Single-phase 1-stage EMI FilterThis figure shows a standard circuit structure forsingle-phase EMI filters.L and CYs reduce the common mode noise; CXsand leakage inductance from L reduce the normalmode noise.R indicates a discharge resistance for capacitors.b. Single-phase 2-stage EMI filterCaseL1L3LINECYRCXCXLOAD2CY4Attenuation [dB]Figure 2.8.2 Circuit Structure Example ofa Single-phase 2-stage EMI filterThe above figure represents a circuit structureexample of placing choke coils in two stages toimprove the attenuation characteristic.The following graph shows an example comparisonof attenuation characteristics for a 1-stage and2-stage EMI filter.[Common Mode]0102030405060708090100110 00.1 0.1 1 10100Frequency [MHz]EMI/EMCFilterTechnical Notes-6? 764 ?NAC-06-472NBC-06-4721-stage2-stageFigure 2.8.3 Example of Comparing Attenuation Characteristicsbetween 1-stage and 2-stage EMI filters.