EPR-31 Datasheet, PDF (31/36 Pages) Power Integrations, Inc. – Engineering Prototype Report for EP-31 Multiple Output 180 W AC-DC Power

01-Feb-05
EPR-31 – Multi-Output, 180 W, PC Main Power Supply
12 Output Ripple Measurements
12.1 Ripple Measurement Technique
For DC output ripple measurements, a modified oscilloscope test probe must be
utilized in order to reduce spurious signals due to pickup. Details of the probe
modification are provided in Figure 31 and Figure 32.
The 5125BA probe adapter is affixed with two capacitors tied in parallel across
the probe tip. The capacitors include one (1) 0.1 µF/50 V ceramic type and one
(1) 1.0 µF/50 V aluminum electrolytic. The aluminum electrolytic type
capacitor is polarized, so proper polarity across DC outputs must be
maintained (see below).
Probe Ground
Probe Tip
Figure 31 − Oscilloscope Probe Prepared for Ripple Measurement
(End Cap and Ground Lead Removed).
Figure 32 − Oscilloscope Probe with Probe Master 5125BA BNC Adapter
(Modified for ripple measurement: wires for probe tip and
ground with two decoupling capacitors connected in parallel).
Page 31 of 36
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