During testing, set the oscilloscope's TIME/DIV to 10uS/div and the bandwidth to 20MHz. The peak-to-peak output voltage displayed on the oscilloscope is the output ripple voltage (including spikes, the peak-to-peak value is the ripple plus noise).
1) The input voltage of the DC stabilized power supply is adjusted to the nominal voltage, and the output current is set to the rated current. Aviation ground power 2, 36V aviation power supply 1, 400HZ variable frequency power supply 7, 115/200V power supply.
2) The ripple of a DC regulated power supply is generally expressed as peak-to-peak. This is the primary testing method. The ripple and noise of a DC regulated power supply are AC components superimposed on the DC output voltage, and measurements are taken under rated load and normal temperature conditions. For switch-mode AC/DC regulated power supplies, the output ripple voltage consists of a series of small pulses with high-frequency content, so peak-to-peak measurements are typically used rather than root mean square (RMS) values. The measurement is indicated in millivolts peak-to-peak (mVp-p). For example, if the peak-to-peak ripple of an AC/DC regulated power supply is 50mV, its RMS value is low, at just 5mV. However, whether it can be used in a particular system requires further consideration. Because the measured ripple contains high-frequency content, special measurement techniques must be employed to obtain accurate measurement results.
To measure all high-frequency harmonics within the ripple spikes, an oscilloscope with a 20MHz bandwidth is typically required. Additionally, during ripple measurements, it is crucial to be extremely careful to avoid introducing erroneous signals into the testing equipment. It is necessary to remove the probe ground clip during measurement, as in a high-frequency radiation field, the ground clip can act like an antenna, absorbing noise and interfering with the measurement results.
To eliminate interference, use a probe measurement method with a grounding ring. This is a method for measuring the ripple voltage of a DC regulated power supply output using a 50Ω coaxial cable. The coaxial cable is directly connected to the oscilloscope. To reduce noise, use an aluminum or copper ground plane during measurement. The measured value is half of the actual value.
