AN1376 Datasheet, PDF (12/35 Pages) STMicroelectronics – 25W QUASI-RESONANT FLYBACK CONVERTER FOR

AN1376 APPLICATION NOTE
7 DYNAMIC LOAD TESTS
Regulated Output
Load condition: +5V, +7V, +12V, +30V:
+3,3V:
Figure 9.
@115 V_AC - 50Hz
FULL LOAD
LOAD 50 %÷100%, 70Hz
@220 V_AC - 50Hz
CH3: +3V3 Vout at test points
CH4: +3V3 Iout
R1: +3V3 Vout before L4
CH1: +30 Vout
CH2: +12 Vout
CH3: +7 Vout
CH4: +3V3 Iout
The pictures show the output voltage regulation against a dynamic load variation of the feed
backed voltage, at the nominal input voltage values. As shown in the left pictures the response
after the connector is not very good from the peak point of view, even if the response is quite
fast. Making the same measure before the filter inductor (L4), at the feed back divider connec-
tion points, the response is much better (≈2.2 %). This means that the filter inductor heavily
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