Specifications

The Difference Between P-P Voltage Noise and RMS Noise
Question: What is the difference between voltage P-P noise and RMS noise specifications?
Answer: Both Vp-p and Vrms are measures for the unwanted ac components of a dc power supplies output. Peak-
to-peak noise is measured from the maximum positive point on the waveform to the most negative voltage point.
This measurement is particularly important for applications where noise spikes could be detrimental to accurate
measurements on a sensitive load, such as r.f. circuitry.
RMS is an abbreviation for root mean square, and it’s accurate measurement requires a true-RMS responding
voltmeter. This measurement is not an ideal representation of dc power supply noise, since fairly high output noise
spikes of short duration could be present in the ripple, and not appreciably increase the RMS value.