RMS versus AVERGAGE

panfilero · 2010-12-08T02:55:56+00:00

ok, here's my questions... and it's coming from looking at alot ofthese switch mode power supply converters, where the voltage out issome relationship with the voltage input and the duty cycle.well... if you have a waveform that is high for 50% of the period, youhave a .5 duty cycle, then on average you have 50% of your peak... ifthe relationship is Vin*D = Vo, and Vin is 10V, then you have 5voltsout...Then you have the RMS value of this same waveform, and it's value isVin * sqrt(D) = 7.07Vwell.... what's the significance of this?If the above waveform was current, and Iin was 10A... and I needed tospec a part, I'd look for the RMS current rating right? and make sureit was above 7.07A... I wouldn't look at the average current rating5A....But then why don't we call Vo = 7.07V and call it a day? why can't wejust use either RMS or average when dealing with these pulsedwaveforms?much thanks!

Dec 08, 2010 42 Replies

Rate this thread:

Jamie 15 years ago

Yes, but I can better remember this value..

Vote

Tabby 15 years ago

But I hate integration...

Vote

m II 15 years ago

That works on *so many* levels!

homer

Vote

Join the Discussion

Have something to add? Share your thoughts — no account required.

Didn't find your answer?

Ask the community — no account required