AN4007 datasheet(14/33 Pages) STMICROELECTRONICS

Part #	AN4007

Description	In several applications, such as LCD or plasma TVs

PDF	33 Pages

Scroll/Zoom	100%

Manufacturer	STMICROELECTRONICS [STMicroelectronics]

Direct Link	http://www.st.com

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14 / 33 page

Test board: design and evaluation

AN4007

14/33

Doc ID 022455 Rev 2

The ripple at the switching frequency superimposed at the output voltage was also

measured. The board is provided with an LC filter to further reduce the ripple without

reducing the overall output capacitor’s ESR.

The voltage ripple across the output connector (VOUT) and before the LC filter (VOUT_PRE)

were measured in order to verify the effectiveness of the LC filter:

Figure 13 shows the

output voltage ripple at full load when the converter input voltage is 115 VAC; while Figure 14

shows the output voltage ripple at full load when the converter input voltage is 230 VAC.

Figure 13.

Output voltage ripple at full load and 230 VAC

AM11352v1

Ch1 (Pk-Pk): 18.73 mV

Ch2 (Pk-Pk): 298.3 mV

M: 20.0 µs/div

VOUT_PRE

VOUT

AN4007 Datasheet(PDF) 14 Page - STMicroelectronics