Due to low ripple dc stableswitching power module is generally formed by ac power by rectifier voltage regulator, and this inevitably in the dc stable quantity mixed with some AC ingredients, this superimposed on the dc steady amount of ac component is called ripple. Ripple component is relatively complex, its form is commonly higher than that of similar power frequency sine wave frequency harmonic, the other is the narrow pulse wave. For different occasions, different requirement of ripple.
For capacitor sophisticated, no matter what kinds of ripple, as long as it's not too big, Normally has not influence the quality of capacitor sophisticated. For program control switching power supply or sound equipment power modules, because the very narrow pulse does not have enough energy to push the loudspeaker paper cone or telephone receiver and form of noise.
So where can have the relax request of ripple. For the audio range similar to sine wave signal, although its range is not too high, but its energy makes the speaker or the receiver buzzing noise. So there must some requests for the ripple, and for some control occasions, due to the narrow pulse reaches a certain height can interfere with digital or logic control unit, reduce the reliability of equipment operation, so for this kind of narrow pulse requires certain restrictions, and for similar ripple sine wave, typically due to its low amplitude, small disturbance to the control unit.
Special switching power supply ripple expressed by peak or RMS, can use absolute, relative also be used to express. For example, a stabilized switching power module with the output 100V5A,measured the valid values for 10 mv of ripple, the 10 mv is the absolute ripple, and relative amounts namely = ripple voltage and output voltage ripple coefficient = 10 mv / 100 v = 0.01%, which is equal to one over ten thousand.