The function of every voltage regulator is to convert a de input voltage into a specific, stable, dc output voltage and maintain that voltage over a wide range of load current and input voltage conditions. To accomplish this, the typical voltage regulator (Figure 5-1) consists of:
- A reference element that provides a known stable voltage level, (VREF).
- A sampling element to sample the output voltage level.
- An error-amplifier element for comparing the output voltage sample to the reference and creating an error signal.
- A power control element to provide conversion of the input voltage to the desired output level over varying load conditions as indicated by the error signal.
Although actual circuits may vary, the three basic regulator types are series. Shunt, and switching. The four basic functions listed above exist in all three regulator types.