June Mini Series Challenge #4

We hope you have enjoyed this miniseries challenge.  

Here is our final and winning question: 

A DC-to-DC converter circuit is shown below. The converter switches in continuous mode at a constant frequency. D is assumed to be an ideal diode. The output voltage VOUT is constantly at 5V. 

  1. What is the name of the converter topology? 
  2. VIN is set to 10V. At what duty cycle the converter is switching? What is the average current drawn from the input at VIN in terms of ILOAD? How do they change if VIN is set to15V?
  3. What change to the circuit is necessary to make it operate as an inverting DC-to-DC converter, i.e., VOUT becomes negative?