Testing Lab of Power Supply/ IT / AV Products

FCC certification for built-in power supplies — embedded power modules, PCB-mount AC-DC converters, and chassis-mount power units — follows the SDOC procedure under FCC Part 15 Subpart B. Unlike enclosed desktop adapters, built-in PSUs rely on the host equipment's enclosure for mechanical protection, EMI shielding, and safety isolation. This integration dependency makes the FCC EMC testing fundamentally a "hosted" evaluation: emissions are measured with the PSU installed in a representative host chassis or test fixture, and the test results are conditioned on the specific installation configuration. This guide provides a technical framework for built-in PSU FCC certification, covering host-dependent test configuration, metal vs. plastic enclosure emission characteristics, product family certification strategy, and coordination with CE-EMC requirements.

Host-Dependent FCC Testing and Enclosure Effects

Built-in PSUs must be tested in a representative host enclosure because the enclosure material, grounding scheme, internal layout, and ventilation design all influence the measured radiated emissions. Metal enclosures provide electromagnetic shielding that typically reduces radiated emissions by 5-15 dB compared to plastic enclosures — the PSU manufacturer should consider testing in both enclosure types if the product is marketed for integration into diverse equipment. The test report must document the enclosure specifications: material, thickness, internal dimensions, PSU mounting position, input/output cable routing, and grounding connections.

Conducted emission testing for built-in PSUs follows standard LISN methodology on the AC input. Radiated emission testing requires the complete assembly — PSU installed in host chassis — to be positioned on the turntable. Ventilation openings and cable exit points are potential radiation leakage paths that must be within the antenna scan coverage. Built-in PSU host-enclosure FCC testing should evaluate multiple chassis configurations if the PSU is marketed across diverse application segments.

OEM Integration and Multi-Market Certification

OEM equipment manufacturers integrating built-in PSUs into their products reference the PSU's FCC test data as evidence supporting the end-product's SDOC compliance. The OEM must verify that the host enclosure design is consistent with the reference installation conditions in the PSU test report. Significant deviations — change from metal to plastic enclosure, different grounding scheme, or repositioning of the PSU within the chassis — may necessitate host-level radiated emission verification testing. For PSU manufacturers, providing FCC test data across both metal and plastic enclosure configurations maximizes the data's applicability to downstream OEM customers.

FCC and CE-EMC testing for built-in PSUs can be coordinated into a single chamber session using the same host enclosure configuration. Built-in PSU FCC and CE dual-standard testing structured from the start minimizes certification effort for manufacturers serving both the US and European markets.

Frequently Asked Questions

This content is provided for industry communication and informational reference only and does not constitute any form of certification commitment, testing advice, or legal opinion. The certification requirements, procedures, and standards referenced herein may change as regulations evolve — please refer to the latest official announcements from the relevant authorities. Specific certification requirements, timelines, and costs must be evaluated by professional engineers based on the actual product. For inquiries, please contact us by phone.

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