MAX6160 dropout voltage limit the maximum output voltage. This circuit is useful when the

voltage reference needs to be programmed in the field to different levels and absolute accuracy

is not critical but low drift is required.

Figure 2. The MAX6160 digitally adjustable output circuit with the MAX5462 32-tap digital pot

This circuit is capable of setting the output voltage to within 5% of 2.048V, 7% of 2.50V, 11% of

4.096V, and 16% of 5.00V. The key spec for the MAX5462 is the ratiometric resistance

temperature coefficient (tempco) of 5ppm/°C. This low-drift characteristic enables drift

performance comparable to a fixed output voltage reference with the flexibility to coarsely adjust

the output.

The same topology can be used with the MAX5401 (a 100-kilohm, 256-tap digital pot), shown in

Figure 3, to increase the resolution by roughly an order of magnitude. This circuit is capable of

setting the output voltage to within 0.6% of 2.048V, 0.8% of 2.50V, 1.3% of 4.096V, and 1.6% of

5.00V. It has the same benefits as the circuit in Figure 2 but with this increased resolution.