Document Number: 002-08393 Rev.*A

Page 19 of 37

MB39C601

8.9

TZE Part

MB39C601 requires all of the following three conditions in order to start the next switching cycle.

2. The time since the last turn-on edge must be longer than the minimum switching period set by MB39C601 (nominally 7.5µs

which equals 133 kHz).

3. Immediately after zero energy detection at the TZE pin. Or, the time since the last zero energy detection must be longer than

Starting switching cycle diagram

The TZE pin is connected with Auxiliary Winding of the transformer through the resistance division, and detects zero energy as

shown "TZE pin Connection".

A delay, 50ns to 200ns, can be added with CTZE to adjust the turn-on of the primary switch with the resonant bottom of Primarty

Winding waveform.

Switching Waveform at detecting zero Energy