SOT23, 3V/5V, Single-Supply, Rail-to-Rail
Instrumentation Amplifiers
Functional Diagrams
V
DD
V
DD
V
DD
MAX4461
MAX4462
MAX4460
OUT
OUT
OUT
SHDN
FB
g
g
M
g
M
M
g
g
g
M
M
M
REF
V
SS
Figure 1. Functional Diagrams
Detailed Description
V
DD
The MAX4460/MAX4461/MAX4462 family of instrumen-
tation amplifiers implements Maxim’s proprietary indi-
rect current-feedback design to achieve a precision
specification and excellent gain-bandwidth product.
These new techniques allow ground-sensing capability
combined with an ultra-low input current and an
increased common-mode rejection.
MAX4460
OUT
FB
R2
R1
The differential input signal is converted to a current by
an input transconductance stage. An output transcon-
ductance stage converts a portion of the output voltage
(equal to the output voltage divided by the gain) into
another precision current. These two currents are sub-
tracted and the result is fed to a loop amplifier with a
class AB output stage with sufficient gain to minimize
errors (Figure 1).
g
M
g
M
The MAX4461U/T/H and MAX4462U/T/H have factory-
trimmed gains of 1, 10, and 100, respectively. The
MAX4460 has an adjustable gain, set with an external
pair of resistors between pins OUT, FB, and GND
(Figure 2).
Figure 2. MAX4460 External Resistor Configuration
The MAX4461U/T/H has a shutdown feature to reduce
the supply current to less than 1µA. The MAX4461U/
T/H output is internally referenced to ground, making
the part suitable for unipolar operations.
The MAX4462U/T/H has a reference input (REF) which
is connected to an external reference for bipolar opera-
tion of the device. The range for V
is 0.1V to (V
-
The MAX4460 has an FB pin that can be used to exter-
nally set the gain through a pair of resistors (see Setting
the Gain (MAX4460) section). The MAX4460 output is
internally referenced to ground, making the part suitable
for unipolar operations.
REF
DD
1.7V). For full output-swing capability, optimal perfor-
mance is usually obtained with V = VDD/2.
REF
The MAX4460/MAX4461/MAX4462 operate with single-
supply voltages of 2.85V to 5.25V. It is possible to use the
MAX4462U/T/H in a dual-supply configuration with up to
2.6V at V and V , with REF connected to ground.
DD
SS
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