About ripple and noise

This page is about ripple and noise of AC adapter, switching power supply. It describes the basic knowledge on ripple and noise and the relationship with the AC adapter. If you have any questions, please do not hesitate to contact us.

"Ripple" and "Noise" are one of the items indicating the performance of the AC adapter and are written in our specifications as follows. (Extract from UNIFIVE Product Specification)

itemspecminRepresentative valuemax
output 24V
Output voltage range Typical Output voltage 22.8V 25.2V
Load current 1A
Ripple input(typ)Full load current 25℃ 150mV
noise input(typ)Full load current 25℃ 150mV
output Retention time input(typ),Full load current 50Hz 10mS
Activation wait time 2S

Both "ripple" and "noise" are fine DC fluctuations contained in the output voltage which is direct current and should be originally 0 (zero), but in principle it is difficult to completely eliminate it, small ripple noise is the key factor of AC adapter's quality.

The smaller the smaller the smaller the "better AC adapter", is not that kind of thing, in order to reduce the "ripple" or "noise" because it affects the quantity and size of parts used, it is big and heavy , And the price will be higher.

Therefore, it is necessary to select optimum performance for the equipment you use and select "AC adapter".

Therefore, although it explains the difference between "ripple" and "noise", it is stipulated in the standards of the Japan Electronics and Information Technology Industries Association = JEITA as shown in the figure below.

(Extracted from JEITA)

"Ripple" is fluctuation consisting of frequency component of 50/60 Hz of AC power supply, and "noise" is fluctuation consisting of frequency component of several ten kHz or more caused by switching of AC adapter. There is a relation between the combination of them and "ripple noise", "ripple", "noise" <"ripple noise" <"ripple" + "noise".

At our company, various AC adapters are prepared according to the application, individual specifications can also be downloaded. We are also good at custom correspondence. If you have any questions, please do contact us.

You can get the product catalog in PDF.


The standard of JEITA introduced this time can be purchased from the following page. There are also things that you can see for free if you are only browsing, so please refer to that for details.

JEITA Standard> General Electronic Components Division> Conversion Parts Relationship

You can get the product catalog in PDF.

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Since 1989, UNIFIVE has maintained the quality of their AC power adapters and switching power supplies through a rigorous quality,

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