Simple Efficiency Formula for Regulated DC-to-DC Converters

A very simple circuit loss model and an efficiency formula are given for regulated pulsewidth modulated (PWM) dc-to-dc converters which can be used by manufacturers of off-the-shelf converters to characterize the efficiency of a converter by specifying only two parameters at each input voltage. In this model, the overhead losses are modeled by a current source and all remaining losses are modeled by a series resistor. The efficiency formula is shown to fit remarkably well the efficiency data of a number of representative low power and low voltage commercial dc-to-dc converters regardless of their topology as well as custom designed high power, high voltage converters. The results presented are useful mainly to end-users for power system management.