OPERATING VOLTAGE
APPLICATIONS INFORMATION
The INA152 operates from single (+2.7V to +20V) or dual
(±1.35V to ±10V) supplies with excellent performance. Speci-
fications are production tested with +5V and ±10V supplies.
Most behavior remains unchanged throughout the full oper-
ating voltage range. Parameters that vary significantly with
operating voltage are shown in the typical performance
curves.
The INA152 is a low-power difference amplifier suitable for
a wide range of general-purpose applications. Figure 1
shows the basic connections required for operation of the
INA152. Decoupling capacitors are strongly recommended
in applications with noisy or high-impedance power sup-
plies. The capacitors should be placed close to the device
pins, as shown in Figure 1.
As shown in Figure 1, the differential input signal is con-
nected to pins 2 and 3. The source impedances connected to
the inputs must be nearly equal to assure good common-
mode rejection. An 8Ω mismatch in source impedance will
degrade the common-mode rejection of a typical device to
approximately 80dB (a 16Ω mismatch degrades CMR to
74dB). If the source has a known impedance mismatch, an
additional resistor in series with the opposite input can be
used to preserve good common-mode rejection.
INPUT VOLTAGE
The INA152 can accurately measure differential signals that
are above and below the supply rails. Linear common-mode
range extends from 2 • [(V+) – 1V] to 2 • (V–) (nearly twice
the supplies). See the typical performance curve, “Input
Common-Mode Voltage vs Output Voltage”.
OFFSET VOLTAGE TRIM
The INA152’s internal resistors are accurately ratio trimmed
to match. That is, R1 is trimmed to match R2, and R3 is
trimmed to match R4. However, the absolute values may not
be equal (R1 + R2 may be slightly different than R3 + R4).
Thus, large series resistors on the input (greater than 250Ω),
even if well matched, will degrade common-mode rejection.
The INA152 is laser trimmed for low offset voltage and drift.
Most applications require no external offset adjustment.
Figure 2 shows an optional circuit for trimming the output
offset voltage. The output is referred to the output reference
terminal (pin 1), which is normally grounded. A voltage
applied to the Ref terminal will be summed with the output
signal. This can be used to null offset voltage, as shown in
Figure 2. The source impedance of a signal applied to the Ref
terminal should be less than 10Ω to maintain good common-
mode rejection.
Circuit-board layout constraints might suggest possible varia-
tions in connections of the internal resistors. It might appear
that pins 1 and 3 could be interchanged, however, because of
the ratio trimming technique used (see paragraph above)
CMRR will be degraded. If pins 1 and 3 are interchanged,
pins 2 and 5 must also be interchanged to maintain proper
ratio matching.
INA152
R1
R2
V–
V+
2
5
6
V2
1µF
1µF
4
7
VO
INA152
R1
R2
40kΩ
40kΩ
10
R3
Ω
V2
–In
2
5
6
3
V3
R4
+V
V
O = V3 – V2
Gain Error = ±0.01%
CMR = 94dB
Nonlinearity = ±0.002%
R3
40kΩ
R4
40kΩ
1
V
O = V3 – V2
100k
Ω
Offset Adjustment
V3
+In
1
3
100k
Ω
Range = ±1mV
10
Ω
–V
FIGURE 1. Precision Difference Amplifier (Basic Power
Supply and Signal Connections).
FIGURE 2. Offset Adjustment.
INA152
SBOS184
8
TI [ TEXAS INSTRUMENTS ]
