Datasheet

Applications Information
The MAX5400/MAX5401 are intended for a variety of
circuits that require accurate, fine-tuning adjustable
resistance, such as adjustable voltage or adjustable
gain circuit configurations. The MAX5400/MAX5401 are
primarily used in either a potentiometer divider or a
variable resistor configuration.
Adjustable Current-to-Voltage Converter
Figure 5 shows the MAX5400/MAX5401 being used
with a MAX4250 low-noise op amp to fine tune a cur-
rent-to-voltage converter. Pins H and W of the
MAX5400/MAX5401 are connected to the node
between R3 and R2 and pin L is connected to ground.
Adjustable Gain Amplifier
The MAX5400/MAX5401 are used again with the
MAX4250 to make a digitally adjustable gain circuit as
shown in Figure 6. The normal feedback resistor is
replaced with the MAX5400/MAX5401 in a variable
resistor configuration so that the gain of the circuit can
be digitally controlled.
Adjustable Voltage Reference
In Figure 7, the MAX5400/MAX5401 are shown with the
MAX6160 to make an adjustable voltage reference. In
this circuit, the H pin of the MAX5400/MAX5401 is con-
nected to the OUT pin of the MAX6160, the L pin of the
MAX5400/MAX5401 is connected to GND, and the W
pin of the MAX5400/MAX5401 is connected to the ADJ
pin of the MAX6160. The MAX5400/MAX5401 allow pre-
cise tuning of the voltage reference output. A low
5ppm/°C ratiometric tempco allows a very stable
adjustable voltage over temperature.
MAX5400/MAX5401
256-Tap SOT-PoT,
Low-Drift Digital Potentiometers in SOT23
_______________________________________________________________________________________ 7
+5V
R3
V
O
/ I
S
= R
3
(1 + R
2
/ R
1
)+ R
2
R2
R1
MAX4250
V
O
Figure 5. I to V Converter
+5V
V
S
V
O
R2
V
O
/ V
S
= 1 + R
2
/ R
1
R1
MAX4250
Figure 6. 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 4. Serial Data Format