AN2252

Application circuit description

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Figure 15. shows the same waveforms as Figure 13. but at 10% of the specified load. The

storage time is the same as for full load: about 800ns. This proves the good design and

operation of the current transformer that maintains a constant storage time for different

loads and input voltages. Figure 13., Figure 14. and Figure 15. also highlight the valley-

skipping function of the control IC which helps keep the switching frequency within a

reasonable range.

Figure 15.

Primary switch collector voltage, gate voltage and base current at 10%

load and minimum input voltage

Note:

Channel 1 shows the switch collector voltage (dark blue), channel 2 shows the gate voltage

(light blue) and channel 4 shows the base current (green).

Figure 16. shows that the storage time remains stable even under maximum input voltage

conditions.

Figure 16.

Primary switch collector voltage, gate voltage and base current at 10%

load and maximum input voltage