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EMC Pre-Compliance Testing

EMC, EMI & EMS Acronyms

Electromagnetic Compatibility (EMC): The ability of a device to operate properly in its environment without disrupting the operation of other close-by devices.

Electromagnetic Interference (EMI): This represents the electromagnetic energy a device emits, which can cause problems in other close-by devices if it is too high.

Electromagnetic Immunity (EMS): Tolerance to electromagnetic emissions.

Equipment & Standards

To properly measure the EMI that a device emits, you need special equipment defined by the CISPR 16-1-1 specification. To learn more about our EMI testing equipment, please check out How We Test Power Supply Units.

In order to minimize EMI noise, some standards have been established. The corresponding standards for Information Technology products are CISPR 32 and its derivative EN 55032. In the EU, every product featuring the "CE" marking has to comply with EN 55032. Both CISPR 32 and EN 55032 divide devices into two classes, A and B. B-class equipment is for domestic environments, so its allowed EMI emissions are significantly lower than for A-class devices.

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CISPR 32 / EN55032 Limits
CISRP 32/ EN 55032 Class A Conducted EMI Limit
Frequency of Emission (MHz)	Conducted Limit (dBuV)
Quasi-peak	Average
0.15 - 0.50	79	66
0.50 - 30.0	73	60
CISPR 32/ EN 55032 Class B Conducted EMI Limit
Frequency of Emission (MHz)	Conducted Limit (dBuV)
Quasi-peak	Average
0.15 - 0.50	66 - 56	56 - 46
0.50 - 5.00	56	46
5.00 - 30.00	60	50

EMI Results - Average Detector

Two spikes come close to this test's limit. Everything else is notably lower. What matters most, though, is that the BF450G's EMI filtering stage passes the average detector test successfully.

EMI Results - Peak Detector