Voltage Reference

Definition

A voltage reference is a circuit or circuit element that produces a constant voltage output. Measuring voltage requires a standard to measure against, and voltage references provide that standard.

Shunt Voltage References

Shunt voltage references operate in a manner that is functionally equivalent to a Zener diode. The bias current must be set higher than the sum of the maximum quiescent current of the voltage reference and the maximum expected load current. Since shunt voltage references are typically biased with a resistor, the voltage reference can operate on a wide range of input voltages.

Series Voltage References

Series voltage references are functionally similar to a three-terminal regulator. Some series voltage references are designed to also operate in shunt mode by biasing the output pin and leaving the input pin open circuit. Series mode voltage references have the advantage that they draw only load and quiescent current from the input supply.

Micropower Voltage References

Micropower voltage references are designed to have extremely low quiescent currents (series references) or minimum shunt currents (shunt voltage references). Micropower voltage references are used in applications such as battery-operated systems, portable devices, and current loop instrumentation.