| 摘要 |
A switched power supply (10) includes a sensor (R1, R2) for sensing a load (L) fed by the power supply (10) and a feedback path (22, 24, 26) to control the switching frequency of the switched power supply (10) as a function of the load (L) as sensed by the sensor (R1, R2). The arrangement includes an oscillator (30, 38) to inject into the feedback path (22, 24, 26) an oscillating signal, which produces a spread in the spectrum of the electromagnetic noise produced by the switched power supply (10). The oscillating signal is a low frequency (e.g. 300 Hz) signal, that is a signal having a frequency substantially lower than the switching frequency of the switched power supply (10). A switch (34) may be provided to selectively switch off the oscillating signal to prevent fluctuations in the output of the power supply (10) in the presence of a high load.
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