EPR-33 datasheet(23/32 Pages) POWERINT

Part #	EPR-33

Description	Engineering Prototype Report for EP 33 - 45 W LCD Monitor External Power Supply using TOP247Y (TOPSwitch-GX)

PDF	32 Pages

Scroll/Zoom	100%

Manufacturer	POWERINT [Power Integrations, Inc.]

Direct Link	http://www.powerint.com

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23 / 32 page

28-Mar-2003

EPR-33 – 45 W External Adapter Supply

Page 23 of 32

Power Integrations, Inc.

Tel: +1 408 414 9200 Fax: +1 408 414 9201

www.powerint.com

11.5

Output Ripple Measurements

11.5.1 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 24 and Figure 25.

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).

Figure 24 - Oscilloscope Probe Prepared for Ripple Measurement

(End Cap and Ground Lead Removed).

Figure 25 - Oscilloscope Probe with Probe Master 5125BA BNC Adapter

(Modified with wires for probe ground for ripple measurement

and two parallel decoupling capacitors added).

Probe Ground

Probe Tip

EPR-33 Datasheet(PDF) 23 Page - Power Integrations, Inc.