Danielle Coffing
Motorola

This paper presents a design method for switching regulators using Matlab and Simulink. First, a model is developed using frequency domain transfer functions for a buck switching regulator with voltage mode control. Matlab is then used to calculate the necessary bandwidth of the regulator loop given the power distribution network characteristics and the maximum acceptable output voltage variation for a load step change. The compensation network is calculated for given characteristics of the output filter components. Finally, the stability of the regulator is analyzed over the range of possible load currents. The transfer functions describing the system are used in a generalized regulator model for transient simulations in Simulink. The transient reponse of the Simulink system has been correlated with Spice. The paper also shows how using Matlab to gain insight into how parameter and component variation affect the stability and transient performance of the regulator can decrease the regulator design cycle time.