When the voltage between the S1 and SM pins or the voltage between SM and S2 pins exceeds +/-600 V the secondary side MOSFETs could enter an avalanche mode of operation. The MOSFETs and the 11 DWQ package have been designed and qualified to be robust in this mode of operation to support Dielectric Withstand Testing (HiPot). To help ensure the thermal performance of the the system in this mode of operation, refer to the PCB Layout Guidelines.