A system for analyzing the operation of a switching power converter includes a digital controller for receiving an analog signal representing the output DC voltage of the power converter for comparison to a desired output voltage level and generating switching control signals to control the operation of the power supply to regulate the output DC voltage to said output voltage level. At least one portion of a control loop within the digital controller may be switched into the control loop in a first mode of operation and out of the control loop in a second mode of operation. A microcontroller emulates the operation of the at least one portion of the control loop during the second mode of operation.