I'm developing a flyback converter with the FT838NB1 IC, and I got some doubts about the collector-emitter breakdown voltage of the integrated NPN switching transistor.
Absolute maximum ratings show that the collector to GND voltage can go to 700V:
From the internal schematic I understand that collector to GND value can be considered the collector-emitter breakdown voltage im my circuit, as the emmiter is connected to GND by a low-value resistor (and the current doesn't exceed 0.4 A).
All right so far, because the circuit is operating well, with full load and in universal input voltage range (85 V to 264 V).
But in the Electrical Characteristics section of the datasheet I found a minimum collector-emitter breakdown voltage of 400 V. So for me, reading this information, values larger than 400 V would cause trouble for the BJT.
But as you can see below, the ringing voltage on my circuit is reaching 513 V, and it's working well (I achieved this value with a good snubber; it was worse).
Can someone explain where my interpretation is wrong?