Datasheet

MAX4194–MAX4197
Micropower, Single-Supply, Rail-to-Rail,
Precision Instrumentation Amplifiers
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The accuracy and temperature drift of the R
G
resistors
also influence the IC’s precision and gain drift, and can
be derived from the equation above. With low R
G
val-
ues, which are required for high-gain operation, para-
sitic resistances may significantly increase the gain
error.
Capacitive-Load Stability
The MAX4194–MAX4197 are stable for capacitive loads
up to 300pF (Figure 6a). Applications that require
greater capacitive-load driving capability can use an
isolation resistor (Figure 6b) between the output and
the capacitive load to reduce ringing on the output sig-
nal. However, this alternative reduces gain accuracy
because R
ISO
(Figure 6c) forms a potential divider with
the load resistor.
INPUT
(50mV/div)
OUTPUT
(50mV/div)
50µs/div
Figure 6b. Small-Signal Pulse Response with Excessive
Capacitive Load (R
L
= 25kΩ, C
L
= 1000pF)
INPUT
(50mV/div)
OUTPUT
(50mV/div)
50µs/div
Figure 6c. Small-Signal Pulse Response with Excessive
Capacitive Load and Isolating Resistor (R
ISO
= 75Ω, R
L
=
25kΩ, C
L
= 1000pF)
IN-
(MAX4194)
(INTERNAL, MAX4195)
V
EE
V
REF
V
REF
V
OUT
V
CC
R
ISO
R
L
C
L
IN+
R
G
= ∞
Figure 6a. Using a Resistor to Isolate a Capacitive Load from
the Instrumentation Amplifier (G = +1V/V)
SHDN
(5V/div)
MAX4196
OUT
AC-COUPLED
(V
DIFF
= 200mV,
G = +10V/V)
(500mV/div)
50µs/div
SHDN
(5V/div)
MAX4197
OUT
AC-COUPLED
(V
DIFF
= 20mV,
G = +100V/V)
(500mV/div)
50µs/div
Figure 5c. MAX4197 Shutdown Mode
Figure 5b. MAX4196 Shutdown Mode