Military Embedded Systems

VPX power supplies and EMI filters


March 22, 2018

Leo Carbonneau

Milpower Source

Electro-magnetic interference (EMI) filters are critical components in any electrical design, especially in support of military systems requiring partial or complete qualification to MIL-STD-461. EMI filters are designed to reduce high frequency conducted and radiated electronic noise which may create interference with other electrical devices. Embedding EMI filters into the power supply, a potential signal source, is a key feature in any power supply design.

This holds true in the constrained volume of VPX 3U and 6U form factors. Some VPX power supply designs do not use enough EMI filters, thereby potentially creating a litany of system-level EMI challenges for which the integrator would ultimately bear responsibility.

One such challenge would be the need for a second card slot in a VPX chassis to host a stand-alone EMI filter. In many upgrade or retrofit programs, two card slots are not available to the integrator for a power supply and EMI filter, requiring migration to a larger chassis and space claim challenges.

The integrator should be cautious to source a VPX power supply with an appropriately designed embedded EMI filter.

To learn more about the advantages and characteristics of VPX power supplies, read a white paper from Milpower Source, titled “VPX Power Conversion Guide.”


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