256-Tap, µPoT, Low-Drift,

Digital Potentiometer

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7

Applications Information

The MAX5402 is intended for a variety of circuits where

accurate, fine-tuned adjustable resistance is required,

such as in adjustable voltage or adjustable gain circuit

configurations. The MAX5402 is used in either a poten-

tiometer divider or a variable resistor configuration.

Adjustable Current to Voltage Converter

Figure 4 shows the MAX5402 used with a MAX4250

low-noise op amp to precisely tune a current-to-voltage

converter. Pins H and W of the MAX5402 are connect-

ed to the node between R3 and R2, and pin L is con-

nected to ground.

Adjustable Gain Amplifier

The MAX5402 is used again with the MAX4250 to make

a digitally adjustable gain circuit as shown in Figure 5.

The normal feedback resistor is replaced with the

MAX5402 in a variable resistor configuration, so that

the gain of the circuit can be digitally controlled.

Adjustable Voltage Reference

In Figure 6, the MAX5402 is shown with the MAX6160

to make an adjustable voltage reference. In this circuit,

the H pin of the MAX5402 is connected to the OUT pin

of the MAX6160, the L pin of the MAX5402 is connect-

ed to GND, and the W pin of the MAX5402 is connect-

ed to the ADJ pin of the MAX6160. The MAX5402

allows precise tuning of the voltage reference output. A

low 5ppm/°C ratiometric tempco allows a very stable

adjustable voltage overtemperature.

+5V

R3

R2

R1

MAX4250

W

H

L

MAX5402

Figure 4. I to V Converter

+5V

R2

R1

W

H

L

MAX4250

MAX5402

Figure 5. Noninverting Amplifier

Data Word

B0 (D7)

B1 (D6)

B2 (D5)

B3 (D4)

B4 (D3)

B5 (D2)

B6 (D1)

B7 (D0)

(MSB)

First Bit In

(LSB)

Last Bit In

Figure 3. Serial Data Format