Step-down switching regulators
A substantial percentage of regulator requirements involve stepping down the primary voltage. Although linear regulators can do this, they cannot achieve the efficiency of switching based approaches1. The theory supporting step-down (“buck”) switching regulation is well established, and has been exploited for some time. Convenient, easily applied ICs allowing implementation of practical circuits are, however, relatively new. These devices permit broad application of step-down regulation with minimal complexity and low cost. Additionally, more complex functions incorporating step-down regulation become realizable.
Basic step down circuit
Figure 7.1 is a conceptual voltage step-down or “buck” circuit. ...