Environmental factors directly affect the stability of a voltage reference. While most system designers understand the effects of temperature change on the reference voltage, as defined by temperature coefficient, many do not realize how significant the thermal hysteresis and long term stability can be. Further, even those that do have few options for keeping those errors low.
In addition, plastic IC packaging absorbs water. It is not widely known that the relative humidity can have a significant effect on stability as well. The most effective way to address this is with a hermetic package. Most hermetic packages, including metal cans and ceramic alternatives, are either large, difficult to get, expensive, difficult to use in manufacturing due to leads that require through-hole PCB mounting, or a combination of these.
The LS8 package is a hermetic ceramic package that gives substantially better performance than plastic, while at the same time is small, surface-mount and low-cost as compared to alternatives. Hysteresis and long term stability are improved in this package, and humidity effects are eliminated.