EPR-86 Datasheet, PDF (22/28 Pages) Power Integrations, Inc. – Engineering Prototype Report for EP 86 - 6.6 W Multi-Class Powered Device (PD) for Power over Ethernet (PoE) Using DPA-Switch-(DPA423G)

EP-86 – 6.6 W, 3.3 V, 2 A PoE Powered Device
13-Apr-2006
10.4 Output Ripple Measurements
10.4.1 Ripple Measurement Technique
For DC output ripple measurements, a modified oscilloscope test probe must be utilized
in order to reduce spurious signal pickup. Details of the probe modification are provided
in Figures 22 and 23.
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. Since the aluminum electrolytic type capacitor is polarized,
proper polarity must be observed when connecting it to the output (see below).
Probe Ground
Probe Tip
Figure 22 – Oscilloscope Probe Prepared for Ripple Measurement (End cap and ground lead removed).
Figure 23 – Oscilloscope Probe with Probe Master 5125BA BNC Adapter (Modified with wires for probe
ground for ripple measurement, and two parallel decoupling capacitors added).
Power Integrations, Inc.
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