SMPS is a known electronic power supply which uses switching regulators to convert electricity as efficiently as possible.
Therefore, in order to optimize the efficiency of SMPS, it is advantageous to supply the controller's integrated circuit (“IC”) from a low voltage.
When supplying the controller's IC with a high voltage, an internal series regulator is required, which results in increased losses. Further, with an internal series regulator, dissipation inside the IC can become high.