In the previous lesson, we improved the amplifier, simulated it and demonstrated its performance using SPICE.
In this lesson, we are going to design a voltage regulator, the heart of any power supply.
The need for Voltage Regulators
The purpose of Voltage regulators is to provide a steady supply voltage to the circuits you are designing.
They are the most common circuits (every electronic system no matter what it's function, has at least one), and yet they are often neglected because of their utilitarian nature.
We need voltage regulators because the sources of primary power (like regular batteries, or the AC voltage we get from the wall plug) are usually not very stable, or not stable enough to ensure that our circuits are working within their specifications.
For instance, the voltage we get from a car battery can vary between a high of 14.4 V when the engine is running and the alternator is charging the battery, and as low as 8 or 9 V when you crank the engine on a cold morning. Because there may be positive or negative spikes superimposed to the battery voltage due to other equipment, most automotive equipment is designed to operate with voltages as high as 16V. Internally, some circuits need stable voltage for proper operation, such as the microprocessor used to control the radio. Most microprocessors run from a 3 V or 5 V supply, which should be regulated to within a fraction of a Volt. For instance, many chips designed to operate from a 5 V nominal require the voltage to remain between 4.5 and 5.5 Volts.
Voltage Reference