AN2864 datasheet(12/29 Pages) STMICROELECTRONICS

12 / 29 page

Testing the board

AN2864

12/29

Doc ID 15282 Rev 1

3.2

Precision of the regulation and output voltage ripple

The output voltage of the board is measured in different line and load conditions. Results

are reported in Table 4. The output voltage variation range is a few mV for all the tested

conditions. The VDD voltage is also measured to verify that it is within the operating range of

the device.

The ripple at the switching frequency superimposed on the output voltage is also measured.

The high frequency voltage ripple across capacitor C9 (VOUT_FLY), which is the output

capacitor of the flyback converter before the LC filter, is also measured to verify the

effectiveness of the LC filter. The results are reported in Table 5.

The waveforms of the two voltages (VOUT and VOUT_FLY) are reported in the figures below.

Table 4.

Output voltage and VDD line-load regulation

VINAC (V)

No load

Half load

Full load

VOUT (V)

VDD (v)

VOUT (V)

VDD (V)

VOUT (V)

VDD (V)

5.05

10.7

5.04

23.5

5.04

25.4

115

5.06

10.6

5.04

24.1

5.04

25.4

230

5.06

10.6

5.04

25.3

5.04

25.4

265

5.06

10.4

5.04

25.2

5.04

25.4

Table 5.

High frequency output voltage ripple

VINAC

(VRMS)

No load

Half load

Full load

VOUT (mV)

VOUT_FLY

(mV)

VOUT (mV) VOUT_FLY (mV)

VOUT

(mV)

VOUT_FLY

(mV)

11.1

94.1

26.0

192

41.5

261

115

10.9

90.9

26.1

192

39.7

269

230

12.8

102

26.5

201

274

265

14.7

110

26.7

194

39.4

270

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