The core function of the IC is to switch on each synchronous rectifier MOSFET whenever
the corresponding transformer half-winding starts conducting (i.e. when the MOSFET body
diode starts conducting) and then to switch it off when the flowing current approaches zero.
For this purpose, the IC is provided with two pins (DVS1 and DVS2) able to sense the power
MOSFET drain voltage level. Because each power MOSFET is turned on when its body
diode is conducting, zero voltage turn-on is achieved.