A frequently asked question, not answered by the guide, has been: “How do I make the world’s most accurate current source and current sink?” Figures 1 and 2 respectively show the circuits for making precision current sources and sinks.
The precision current source and sink are based on the new REF102 10.0V voltage reference. With 2.5ppm/°C VOUT drift, and better than 5ppm/1000hrs long-term stability (see table on page 2), this buried-zener-based voltage reference
offers the best performance available from a single-chip voltage reference today. The REF200 uses a band-gap type reference to allow low-voltage two-terminal operation. This makes it a good general-purpose part, but its drift and stability and initial accuracy cannot compare to that of the REF102.