AN2252

Theory of ESBT and quasi-resonant operation

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Figure 1.

Flyback converter switching cycle - primary switch voltage

The zero-switching operation mode was selected because it has a higher efficiency and

produces less EMI. The benefits of using zero-voltage turn-on for the primary switch can be

clearly seen by comparing Figure 2. and Figure 4. The switch voltage obtained with zero-

voltage turn-on has a higher waveform and the drain or collector current is lower.

Figure 2.

Zero voltage turn-on