MAX5402 Datasheet, PDF (7/9 Pages) Maxim Integrated Products – 256-Tap, μPoT, Low-Drift, Digital Potentiometer

256-Tap, µPoT, Low-Drift,
Digital Potentiometer
Data Word
B0 (D7)
B1 (D6)
(MSB)
First Bit In
Figure 3. Serial Data Format
B2 (D5)
B3 (D4)
B4 (D3)
B5 (D2)
B6 (D1)
B7 (D0)
(LSB)
Last Bit In
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.
R3
+5V
W
MAX4250
H
MAX5402
R1
R2
L
V_O
V_O / I_S = R₃(1 + R₂ / R₁) + R₂
Figure 4. I to V Converter
+5V
V_S
V_O
MAX4250
L ^R2 _H
MAX5402
R1
W
V_O / V_S = 1 + R₂ / R₁
Figure 5. Noninverting Amplifier
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