A voltage reference functions as a provider of constant and specific voltage levels, despite any outside variables that could affect the voltage load. Variables such as inconsistent power load, extreme changes in temperature, or a weakening power supply over the course of time are all conditions that are made irrelevant with the usage of a voltage reference. Voltage references can be applied to a multitude of electronic devices because of the different methods that may be used to regulate the voltage powering the devices.
A voltage reference can be made out of a number of different materials, depending on the device it is used in conjunction with. They may be made out of tubes containing neon gas in tube-based devices. They may also be made in circuitry format to be placed inside regulators for different voltages that may be used in variable power supplies. For example, a voltage reference can be used in converters for both analog-to-digital devices and vice versa. The purpose is to deliver a constant voltage to the device, no matter the reasons there could be for voltage variation.
For a long time, the use of voltage references was provided through mercury batteries because of the stability they provided. These batteries are no longer used. The practice was discontinued because of the harmful effects mercury has on both the environment and anyone who comes into direct contact with the substance.
Voltage regulators are available in two different forms, referred to as series and shunt, and have different applications for each type. A series regulator is used when the circuit it is being applied to is powered in series, and has two pins for the input, one for input power and one for grounding. The output is a one-pin connection, where the regulated voltage is thereby delivered.
A shunt voltage regulator only has two terminals, an input and an output. It operates on a low-current basis and outputs a regulated voltage which is buffered through the voltage reference, usually lowering the voltage upon output. The two terminals are simple input and output connections, used simply as a part of completing the circuit.