9 An unregulated dc input voltage varies over the range 35 V V, 70 V. A buck converter reduces this voltage to 28 V; a feedback loop varies the duty cycle as necessary such that the converter output voltage is always equal to 28 V. The load power varies over the range 10 W Pload 1 kW. The element values and the switching frequency are: L = 22 H C = 470 F fs = 75 kHz Losses may be ignored. (a) Over what range of V, and load current does the converter operate in CCM? (b) Determine the maximum and minimum values of the steady-state transistor duty cycle.