STPS15L10D_ Datasheet - STMicroelectronics

INTRODUCTION
In power supplies, the major portion of power losses is due to output rectifiers. The impact of these losses on the efficiency can be expressed by:

η = VF(IOUT) / VOUT

η :efficiency drop due to the diodes.
VF(IOUT) :voltage drop at the output current
   (IOUT) of the converter.
VOUT :output voltage of the converter.

This formula shows that the influence of the forward voltage increases when the output voltage of the power supply decreases.
This parameter becomes very important for the new standard of 3.3V output voltage. Another key parameter is the leakage current which we have to take into account to develop high efficiency low forward voltage drop Schottky with the best trade-off.