Power Supply Circuits
6.1 VOLTAGE REGULATION FUNDAMENTALS
Nearly all electronic systems require one or more sources of stable DC voltage. Yet many systems get their input power from the standard 120-VAC power line. Even battery-powered units may require stable DC voltages at levels other than those provided directly by the battery. Figure 6.1 shows the basic role played by a voltage regulator circuit and where it fits in the power distribution scheme.
FIGURE 6.1 A voltage regulator circuit provides constant voltage to a load.
If the system receives its power from the 120-VAC power line, the first step is usually voltage reduction ...