DocID16493 Rev 2

11/25

AN3089

Functional check

25

3

Functional check

Some flyback waveforms during steady state operation are reported here.

At nominal load conditions, in Figure 4 and Figure 5, it is possible to note that the ZCD

negative-going edge triggers MOSFET’s turn-on, allowing quasi-resonant operation.

Figure 4. Flyback stage waveforms at 115 V –

60 Hz – full load

Figure 5. Flyback stage waveforms at 230 V –

50 Hz – full load

CH1: drain voltage

CH2: CS pin voltage

CH1: drain voltage

CH2: CS pin voltage

CH3: ZCD pin

CH4: bulk voltage

CH3: ZCD pin

CH4: bulk voltage