Figure 6. Plot of Figure 5 circuit of reference voltage output versus pot A and pot B (32-by-32
taps used instead of 256-by-256 taps for clarity)
Summary
Three circuit topologies were presented that provide the capability to digitally adjust the
MAX6160's output voltage. The first topology provides the capability to coarsely adjust the
output voltage over a wide range using a 32- or 256-tap digital pot. The second topology is
capable of finely adjusting the output voltage about a single output voltage by using two fixed
resistors and a 32-tap digital pot. The third topology can finely tune the output voltage over a
wide range by using a dual, 256-tap digital pot. Table 2 summarizes the initial accuracy for each
circuit presented.
Table 2. Summary of Initial Accuracy
Digital Pot Features
Output
Voltage
2.048V
2.500V
4.096V
MAX5462
32T, 100
Kilohms
5%
7%
11%
MAX5401
256T, 100
Kilohms
0.6%
0.8%
1.3%
MAX5160
32T, 50
Kilohms,
Two
Resistors
0.5%
0.5%
0.5%
MAX5415
256T, 100
Kilohms,
Dual
0.06%
0.03%
0.08%
MAXIM [ MAXIM INTEGRATED PRODUCTS ]
