Low EMI for low cost audio supplies

AD-2124 is ideal for low cost audio.

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CamSemi’s RDFC topology delivers ultra-low EMI for offline power supplies for audio and other EMI-sensitive applications. (see our EMI benefits bulletin for more information).

Even at high power levels, this innovative approach achieves the required EMI regulations with significant margins and without needing expensive, bulky common mode (CM) filter components.

CamSemi’s AD-2124 reference design achieves >16 dB quasi-peak margin on conducted emissions to EN550022 – with no Y capacitors or CM inductors - as shown on the plot here.

The design delivers an isolated continuous output of 1.7 A at 12 V (20 W) from a 230 V input, with a peak power capability of 40 W.

Click the chart to view as a PDF or here to see the conducted EMI results table for this 20 W audio PSU design.

Ultra low EMI for AM radios

AD-2080 is a highly cost-effective 20 W average (40 W peak) supply for powering audio equipment that contains EMI-sensitive AM radios.

The majority of today’s hard switching SMPS topologies create EMI that interferes with the AM band radio function, but CamSemi’s unique soft switching resonant waveform approach makes it ideal for audio and enabling designs that achieve very low EMI of >30 dB quasi-peak margin on conducted emissions to EN550022.

The design needs simple screening and a single Common Mode inductor and low value Y-capacitor to deliver exceptionally low conducted EMI. The output cannot even be measured effectively using a commercial EMI set up.

This chart shows the very significant margins achieved for AD-2080.

Click within the chart to view as a PDF or here for a table of results.

Further EMI measurements were also carried out to determine the level of background emissions present in the test set up being used. The tests were run without switching on the mains power to the AD-2080 power supply – click to view the full results.

For more information on these designs and the use of CamSemi C2470 family of controllers in audio and other EMI-sensitive applications, please contact your CamSemi sales representative.