AN1934 Datasheet, PDF (4/32 Pages) STMicroelectronics – This circuit can be used to produce multiple outputs

List of figures
List of figures
AN1934
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Non-isolated flyback converter schematic diagram (variant 1) . . . . . . . . . . . . . . . . . . . . . . . 7
Transformer dimensions, windings and bottom view pin arrangement. . . . . . . . . . . . . . . . . 9
Assembly top (not in scale). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Assembly solder side (not in scale) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
PCB layout (not in scale) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Picture of the converter. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Output regulation characteristics of 5 V output at 125 VDC input voltage
(load current parameter is on 15 V output) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
Output regulation characteristics of 5 V output at 375 VDC input voltage
(load current parameter is on 15 V output) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
Output regulation characteristics of 15 V, output at 125 VDC input voltage
(load current parameter is on 5 V output) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Output regulation characteristics of 15 V, output at 375 VDC input voltage
(load current parameter is on 5 V output) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Efficiency variation with 5 V output current at 125 VDC input voltage
(load current parameter is on 15 V output) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
Efficiency variation with 15 V, output current at 125 VDC input voltage
(load current parameter is on 5 V output) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
Efficiency variation with 5 V output current at 375 VDC input voltage
(load current parameter is on 15 V output) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
Efficiency variation with 15 V output current at 375 VDC input voltage
(load current parameter is on 5 V output) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
V_in=127 VDC, no-load. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
V_in=373 VDC, no-load. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
V_in=127 VDC, nominal load . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
V_in=373 VDC, nominal load . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
V_in=127 VDC, 50% load on both outputs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
V_in=373 VDC, 50% load on both outputs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
V_in=127 VDC, 5 V output shorted, 15 V output no-load . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
V_in=127 VDC, 15 V output shorted, 5 V output no-load . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
V_in=373 VDC, 5 V output shorted, 15 V output no-load . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
V_in=373 VDC, 15 V output shorted, 5 V output no-load . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
Load transient response, 50 mA to 0.5 A on 5 V output, 15 V output unloaded,
V_in=127 VDC. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
Load transient response, 50 mA to 0.5 A on 5 V output, 15 V output nominal load,
V_in=127 VDC. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
Load transient response, 50 mA to 0.5 A on 5 V output, 15 V output unloaded,
V_in=373 VDC. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
Load transient response, 50 mA to 0.5 A on 5 V output, 15 V output nominal load,
V_in=373 VDC. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
Phase L, average detector . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
Phase L, peak detector . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
5 V/500 mA phase N, average detector . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
+15 V/200 mA phase N, peak detector. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
Schematic diagram of non-isolated flyback converter (variant 2) . . . . . . . . . . . . . . . . . . . . 21
Schematic diagram of non-isolated flyback converter (variant 3) . . . . . . . . . . . . . . . . . . . . 22
Output regulation characteristics of 5 V output at 125 VDC input voltage for
variant 3 (load current parameter is on 15 V output) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
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