This paper presents a DSP based digital control design and implementation of a high frequency dc-dc switching power supply. Starting with a dc-dc buck converter and a given set of performance specifications, different control blocks and parameters, used as in the analog control design approach, are reviewed prior to the control design in digital domain. The control loop is then analyzed and the digital controllers are designed using different control design approaches. MATLAB based digital control design approaches presented here are finally validated with multiple test results from a prototype converter.