EPR-21 – 5 V, 30 W DC-DC Converter
19-Nov-02
12.4 Output Ripple Measurements
12.4.1 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 29 and Figure 30.
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 29 − Oscilloscope Probe Prepared for Ripple Measurement.
(End Cap and Ground Lead Removed).
Figure 30 − 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.
Tel: +1 408 414 9660 Fax: +1 408 414 9760
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