Datasheet

®
INA2141
8
APPLICATION INFORMATION
Figure 1 shows the basic connections required for operation
of the INA2141. Applications with noisy or high impedance
power supplies may require decoupling capacitors close to
the device pins as shown.
The output is referred to the output reference (Ref) terminals
(Ref
A
and Ref
B
) which are normally grounded. These must
be low-impedance connections to assure good common-
mode rejection. A resistance of 8Ω in series with a Ref pin
will cause a typical device to degrade to approximately
80dB CMR (G = 1).
The INA2141 has a separate output sense feedback connec-
tions Sense
A
and Sense
B
. These must be connected to their
respective output terminals for proper operation. The output
sense connection can be used to sense the output voltage
directly at the load for best accuracy.
SETTING THE GAIN
Gain of each IA can be independently selected with a jumper
connection as shown in Figure 1. G = 10V/V with no jumper
installed. With a jumper installed G = 100V/V. To preserve
good gain accuracy, this jumper must have low series
resistance. A resistance of 0.5Ω in series with the jumper
will decrease the gain by 0.1%.
Internal resistor ratios are laser trimmed to assure excellent
gain accuracy. Actual resistor values can vary by approxi-
mately ±25% from the nominal values shown.
Gains between 10 and 100 can be achieved by connecting an
external resistor to the jumper pins. This is not recom-
mended, however, because the ±25% variation of internal
resistor values makes the required external resistor value
uncertain. A companion model, INA2128, features accu-
rately trimmed internal resistors so that gains from 1 to
10,000 can be set with an external resistor.
DYNAMIC PERFORMANCE
The typical performance curve “Gain vs Frequency” shows
that despite its low quiescent current, the INA2141 achieves
wide bandwidth, even at high gain. This is due to its current-
feedback topology. Settling time also remains excellent at
high gain.
NOISE PERFORMANCE
The INA2141 provides very low noise in most applications.
Low frequency noise is approximately 0.2µVp-p measured
from 0.1 to 10Hz (G = 100). This provides dramatically
improved noise when compared to state-of-the-art chopper-
stabilized amplifiers.
FIGURE 1. Basic Connections.
A
1
A
2
A
3
6
(11)
7 Sense
(10)
(12)
(13)
(14)
(16)
(15)
40kΩ40kΩ
40kΩ40kΩ
9
8
2
4
3J
J
1
Pin numbers for
Channel B shown
in parenthesis.
V
IN
V
IN
G = 10V/V
Open Circuit
G = 100V/V
Connect Jumper
V+
V–
INA2141
–
+
5
Over-Voltage
Protection
25kΩ
25kΩ
Over-Voltage
Protection
Load
V
O
= G • (V
IN
– V
IN
)
+
–
0.1µF
0.1µF
NOTE: If channel is unused,
connect inputs to ground, sense
to V
O
, and leave Ref open-circuit.
+
–
V
O
Also drawn in simplified form:
INA2141
Ref
V
O
V
IN
–
V
IN
+
Ref
5050Ω
252Ω
252Ω