A dc-dc converter is needed for a telephone switch system. this system requires 5 V at levels between 50 W and 500 W. The avaliable source is 48 V bus. The bus might ary by +/- 20%, especially because battery backup might be the only source of power at times. The input bus is referenced to earth ground. Suggest an appropriate conversion circuit for this application. Isolation is not required. Define operating characteristics of this converter. Select component values to provide maximum output ripple of +/- 1%.