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Do the AC/DC converters need any external components?
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All AC/DC converters contain built-in mains filters, so no external components are necessary. However, some uses require an input fuse, which must be added externally. The –ST option (converters pre-mounted on an insulated PCB with screw terminal input and output connections) also contain an input fuse as standard.
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Can I use the Common Mode Choke used in my EMI filter to limit the Inrush current as well?
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The inrush current is dependent on the converter, the load (especially the capacitive load) and the impedance of the primary power supply. Therefore, there is no recommended value for the inrush limiting inductor as this need to be individually worked out for each application. Having said that, usually 22µH~100µH works ok.
A CMC is a good inrush current limiter because the core does not go into saturation with high currents (the +ve inrush current is balanced out by the -ve inrush current), so it has a dual purpose: EMC filter and inrush limiting. However, for high power converters it is sometimes better to use a low inductance, high current, choke that is selected to reduce inrush rather than a high inductance choke selected for the best EMC filtering because otherwise too much power could be lost through the choke's resistance during normal operation.
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Do RECOM products include EMI filtering?
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EMI filtering is not included inside the converters. However, an external EMI filter is suggested in our Application Notes.
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Is required any input or output capacitor?
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For normal function, no external capacitor is needed. For EMI filtering, consult our recommendations in our Application Notes.
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Are these parts EN-55022 Class B certified?
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EMI filtering is not included inside the converters. However, an external EMI filter is suggested in our Application Notes for Class A and Class B. Most converters are Class B for radiated emissions or offer the option of a shielded metal case.
