MP9989 - Mosfet is not switching

I am using the MP9989 in an two switch forward converter design for high side rectification. VDD is at 6.7 V as secified in the datasheet. Looking at the output waveform the drain source voltage is constant at 0.7 V when the MP9989 is conducting. So i assume only the body diode of the device is conducting and the gate is not powered.

Output Voltage is 5.5 V.

Output current is up to 15 A.

I tested with and without external VDD source.

What conditions can keep the Mosfet from conducting?

Hi C.Lenau:

Welcome to our community.
I am sorry but MP9989 is designed for Flyback converters only. Therefore it cannot be used in Forward converter applications