SG1540/SG2540/SG3540
APPLICATIONS INFORMATION (continued)
The voltage waveform at +VIN is shown in Figure 4 with these resistor values and with CSTART = 3µF. Notice that two tries are required
before the +15 volt bootstrap winding becomes active.
FIGURE 4 - STARTUP VOLTAGE WAVEFORM
FIGURE 5 - SECONDARY-SIDE START-UP WITHOUT A LINE TRANSFORMER
4/90 Rev 1.1 2/94
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