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Thread: Interpreting ripple waveforms? (Enermax Modu82+)

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    Default Interpreting ripple waveforms? (Enermax Modu82+)

    Looking for info about PSUs in [h]ard|OCP (I like their PSU reviews near as much as jonnyGURU.com ones) I have seen Enermax Modu82+ 625W (the model I'm really interested in is Pro82+, but it's supposed to be exactly the same without the modular conections), but I have a doubt about the interpretation of the ripple waveforms. It's as follows:

    Ripple at 100% load 120v (it's a shame they don't make the tests at 220v...): http://enthusiast.hardocp.com/image....lfOF84X2wuZ2lm

    Looking at 12v1 (for example) the reviewer says there's a ripple of 45mV max (as far as I've seen from other of their reviews each mark in the vertical axis is 10mv? I'm not an expert and I can't interpret the numbers given in the bottom-right corner).

    The question is that it seems to be two different waveforms, one of high frequency inside other of much lower frequency. There is not a single change of more than around 20mV along the graphic (the high frequency changes), but because of the second low-freq waveform if you calculate the difference between the lower voltage measure in the graph and the higher one, you get that ~45mV difference.

    Intuitively (but I can be plainly wrong as I've not education in the matter, only intuitions XD) I'd say that such a waveform should be nearer to a ripple of 20mV than a 45mV one considering how it affects components...

    Is there someone by here (yes, I know there is ) more educated than I that could tell me about this matter? Am I right or wrong? How this "double" waveform affect components?

    Lots of thanks, and sorry about the great-big-boring piece of text, I wanted to explain my question the better I'd be able to.

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    CMIIW
    the low freq. waveform = ripple
    the high freq. waveform = noise

    this noise will be filtered by L-C components

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    Quote Originally Posted by Farinorco View Post
    Looking for info about PSUs in [h]ard|OCP (I like their PSU reviews near as much as jonnyGURU.com ones) I have seen Enermax Modu82+ 625W (the model I'm really interested in is Pro82+, but it's supposed to be exactly the same without the modular conections), but I have a doubt about the interpretation of the ripple waveforms. It's as follows:

    Ripple at 100% load 120v (it's a shame they don't make the tests at 220v...): http://enthusiast.hardocp.com/image....lfOF84X2wuZ2lm

    Looking at 12v1 (for example) the reviewer says there's a ripple of 45mV max (as far as I've seen from other of their reviews each mark in the vertical axis is 10mv? I'm not an expert and I can't interpret the numbers given in the bottom-right corner).

    The question is that it seems to be two different waveforms, one of high frequency inside other of much lower frequency. There is not a single change of more than around 20mV along the graphic (the high frequency changes), but because of the second low-freq waveform if you calculate the difference between the lower voltage measure in the graph and the higher one, you get that ~45mV difference.

    Intuitively (but I can be plainly wrong as I've not education in the matter, only intuitions XD) I'd say that such a waveform should be nearer to a ripple of 20mV than a 45mV one considering how it affects components...

    Is there someone by here (yes, I know there is ) more educated than I that could tell me about this matter? Am I right or wrong? How this "double" waveform affect components?

    Lots of thanks, and sorry about the great-big-boring piece of text, I wanted to explain my question the better I'd be able to.
    The spec and tolerances are written for ripple and noise combined which is why I write the article to say ripple/noise (or to keep from being repetitive in the text sometimes I say amplitude of the traces or trace amplitude etc) is ~45mV. The point is since its combined which the device sees and combined which is in the specification I report the peak combined value.

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    OK, thank you both for your atention. I think I get it. So 45mV is for ripple+noise, which are not the same thing (I though they were, now I know they don't), but then I've a new doubt, because I realise now that same ripple+noise numbers can correspond to way different waveforms... so are the numbers only a part from the whole picture, or are they THE important thing?

    I mean... both of next graphics correspond to ripple/noise measures of ~45mV on 12v1 rail (I think... correct me if I'm wrong, please). Is any of them preferable to the other? And could you give me a little explanation about why, or a link where I could read it?

    Enermax Modu82+ 625W @624W load: http://enthusiast.hardocp.com/image....lfOF84X2wuZ2lm

    Corsair TX-650 @584W load: http://enthusiast.hardocp.com/image....hfOF82X2wuZ2lm

    Lot's of thanks again, let's see if I finally get the picture to interpret those graphs...

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    The peak values are generally the important thing as the specification is designed to accommodate both in properly designed devices. So really neither is preferable over the other to the down stream components but more ripple in the waveform as opposed to switching noise can show differences in design etc.

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    Thanks for the quick response, Spectre. So I really should worry only about the peak difference numbers (so 45mV of ripple/noise should be the same from the point of view of the devices plugged into the PSU, be it the first or the second waveforms).

    Well, I think that clears my mind a little

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