AN629 Datasheet, PDF (3/6 Pages) Maxim Integrated Products – Digitally Adjustable Voltage References

Figure 3. The MAX6160 digitally adjustable output circuit with the MAX5401 256-tap digital pot
Fine Adjustment over a Narrow Voltage Range
The circuit in Figure 4 uses the MAX5160 (a 32-tap digital pot) with two fixed precision resistors
to finely tune around a specific output voltage. The tuning resolution is increased and the range
is decreased as the ratio of the total fixed resistance to the digital pot resistance is increased.
Table 1 shows the resistor-value selection optimized to achieve 0.5% tuning accuracy. These
resistor values can be altered depending on the requirements for initial accuracy and drift.
Figure 4. The MAX6160 digitally adjustable output circuit with the MAX5160 32-tap digital pot
and fixed precision resistors