MAX4195 Maxim, MAX4195 Datasheet - Page 10

• Manufacturer Part Number: MAX4195
• Description: The MAX4194 is a variable-gain precision instrumentation amplifier that combines Rail-to-Rail; single-supply operation, outstanding precision specifications, and a high gain bandwidth
• Manufacturer: Maxim

Figure 4 illustrates the MAX4194 typical common-mode
input voltage range over output voltage swing at unity-
gain (pins 1 and 8 left floating), with a single-supply
voltage of V
V
input voltage range of the input amplifiers (V
V
differential swing. The other points (B, C, E, and F) are
determined by the input voltage range of the input
amps minus the differential input amplitude necessary
to produce the associated V
configurations, the V
points (B, C, E, and F) since a smaller differential volt-
age is necessary for the given output voltage.
The MAX4194–MAX4197’s output stage incorporates a
common-source structure that maximizes the dynamic
range of the instrumentation amplifier.
The output can drive up to a 25kΩ (tied to V
tive load and still typically swing within 30mV of the
rails. With an output load of 5kΩ tied to V
put voltage swings within 100mV of the rails.
The MAX4195–MAX4197 feature a low-power shutdown
mode. When the shutdown pin (SHDN) is pulled low,
the internal amplifiers are switched off and the supply
current drops to 8µA typically (Figures 5a, 5b, and 5c).
Micropower, Single-Supply, Rail-to-Rail,
Precision Instrumentation Amplifiers
Table 1. MAX4194 External Gain Resistor
Selection
*Leave pins 1 and 8 open for G = +1V/V.
10
REF
CC
GAIN (V/V)
- 1.1V) since, with +2.5V output, there is zero input
______________________________________________________________________________________
+10,000
= V
+1,000
+2,000
+5,000
+100
+200
+500
+10
+20
+50
+1
+2
+5
CC
CC
/2 = +2.5V. Points A and D show the full
V
= +5V and a bias reference voltage of
CM
CLOSEST R
CM
vs. V
Rail-to-Rail Output Stage
range will increase at the end-
49.9k
12.4k
5.62k
2.61k
1.02k
49.9
24.9
4.99
511
249
100
(Ω)
∞ *
10
OUT
OUT
G
(1%)
. For the higher gain
Characterization
Shutdown Mode
CLOSEST R
CC
CC
EE
5.6k
2.7k
1.0k
51k
12k
510
240
100
/2, the out-
(Ω)
∞ *
5.1
51
24
10
/2) resis-
- 0.2V to
G
(5%)
This disables the instrumentation amplifier and puts its
output in a high-impedance state. Pulling SHDN high
enables the instrumentation amplifier.
The MAX4194’s gain is set by connecting a single,
external gain resistor between the two RG pins (pin 1
and pin 8), and can be described as:
where G is the instrumentation amplifier’s gain and R
is the gain-setting resistor.
The 50kΩ resistor of the gain equation is the sum of the
two resistors internally connected to the feedback loops
of the IN+ and IN- amplifiers. These embedded feed-
back resistors are laser trimmed, and their accuracy
and temperature coefficients are included in the gain
and drift specification for the MAX4194.
Figure 4. Common-Mode Input Voltage vs. Output Voltage
Figure 5a. MAX4195 Shutdown Mode
5
4
3
2
1
0
0
MAX4194/MAX4195
G = +1V/V
REF = +2.5V/+1.5V
0.03
B
C
Applications Information
1
G = 1 + 50kΩ / R
Setting the Gain (MAX4194)
OUTPUT VOLTAGE (V)
50µs/div
2
A
D
3
V
V
T
CC
EE
A
= +25°C
= 0
= +5V/+3V
G
4
4.97
F
E
MAX4195
OUT
AC-COUPLED
(V
(500mV/div)
SHDN
(5V/div)
G = +1V/V)
5
DIFF
= 2V,
G