AN1934 Datasheet, PDF (22/32 Pages) STMicroelectronics – This circuit can be used to produce multiple outputs

Circuit description
AN1934
1.3.1
1.3.2
Circuit operation (variant 3)
The schematic diagram is depicted in Figure 34 and is very similar to the schematic of
variant 2. It has only one output rectifier diode and one output electrolytic capacitor. The 5 V
linear regulator is directly supplied from 15 V output. There are two sub-variants. Depending
on the output current requirement for 5 V output, U3 or U4 can be mounted.
Figure 34. Schematic diagram of non-isolated flyback converter (variant 3)
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Evaluation and measurements
The output regulation characteristics measured on 5 V output can be seen in Figure 35. It
shows the voltage variation of the 5 V output when a different load is applied to 15 V output.
Figure 36 shows the same characteristic as Figure 35 but measured at 375 VDC input
voltage.
Figure 35. Output regulation characteristics of 5 V output at 125 VDC input voltage for
variant 3 (load current parameter is on 15 V output)















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DocID10353 Rev 2