TABLE OF CONTENTS In all switching converters, the output voltage v( t) is a function of the input line voltage v g( t), the duty cycle d( t), and the load current i load( t), as well as the converter circuit element values. In a dc-dc converter application, it is desired to obtain a constant output voltage v( t) = V, in spite of disturbances in v g( t) and i load( t), and in spite of variations in the converter circuit element values. The sources of these disturbances and variations are many, and a typical situation is illustrated in Fig. 9.1. The input voltage v g( t) of an off-line power supply may typically contain periodic variations at the second harmonic of the ac power system frequency (100 Hz or 120 Hz), produced by a rectifier circuit. The magnitude of v g( t) may also vary when neighboring power system loads are switched on or off. The load current v load( t) may contain variations of significant amplitude, and atypical power supply specification is that the output voltage must remain within a specified range (for example, 3.3 V 0.05 V) when the load current takes a step change from, for example, full rated load current to 50% of the rated current, and vice versa The values of the circuit elements are constructed to a certain tolerance, and so...
