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參數(shù)資料
| 型號(hào)： | INA125P |
| 元件分類： | 測(cè)量放大器 |
| 英文描述： | Very High Accuracy Instrumentation Amplifier |
| 中文描述： | 極高精度儀表放大器 |
| 文件頁數(shù)： | 11/13頁 |
| 文件大?。?/td> | 273K |
| 代理商： | INA125P |
11
INA125
The 60k
term in equation 1 comes from the internal metal
film resistors which are laser trimmed to accurate absolute
values. The accuracy and temperature coefficient of these
resistors are included in the gain accuracy and drift specifi-
cations of the INA125.
The stability and temperature drift of the external gain
setting resistor, R
G
, also affects gain. R
G
’s contribution to
gain accuracy and drift can be directly inferred from the gain
equation (1). Low resistor values required for high gain can
make wiring resistance important. Sockets add to the wiring
resistance, which will contribute additional gain error (pos-
sibly an unstable gain error) in gains of approximately 100
or greater.
OFFSET TRIMMING
The INA125 is laser trimmed for low offset voltage and
offset voltage drift. Most applications require no external
offset adjustment. Figure 2 shows an optional circuit for
trimming the output offset voltage. The voltage applied to
the IA
REF
terminal is added to the output signal. The op amp
buffer is used to provide low impedance at the IA
REF
terminal to preserve good common-mode rejection.
FIGURE 2. Optional Trimming of Output Offset Voltage.
10k
OPA237
±10mV
Adjustment Range
100
100
100μA
1/2 REF200
100μA
1/2 REF200
V+
V–
R
G
INA125
IA
REF
V
O
V
IN
–
V
IN
+
INPUT BIAS CURRENT RETURN
The input impedance of the INA125 is extremely high—
approximately 10
11
. However, a path must be provided for
the input bias current of both inputs. This input bias current
flows out of the device and is approximately 10nA. High
input impedance means that this input bias current changes
very little with varying input voltage.
Input circuitry must provide a path for this input bias current
for proper operation. Figure 3 shows various provisions for
an input bias current path. Without a bias current path, the
inputs will float to a potential which exceeds the common-
mode range, and the input amplifiers will saturate.
If the differential source resistance is low, the bias current
return path can be connected to one input (see the thermo-
couple example in Figure 3). With higher source impedance,
using two equal resistors provides a balanced input with
possible advantages of lower input offset voltage due to bias
current and better high frequency common-mode rejection.
INPUT COMMON-MODE RANGE
The input common-mode range of the INA125 is shown in
the typical performance curves. The common-mode range is
limited on the negative side by the output voltage swing of
A
2
, an internal circuit node that cannot be measured on an
external pin. The output voltage of A2 can be expressed as:
V
02
= 1.3V
IN
– (V
IN
– V
IN
) (10k
/R
G
)
(voltages referred to IA
REF
terminal, pin 5)
The internal op amp A
2
is identical to A
1
. Its output swing
is limited to approximately 0.8V from the positive supply
and 0.25V from the negative supply. When the input com-
mon-mode range is exceeded (A
2
’s output is saturated), A
1
can still be in linear operation, responding to changes in the
non-inverting input voltage. The output voltage, however,
will be invalid.
PRECISION VOLTAGE REFERENCE
The on-board precision voltage reference provides an accu-
rate voltage source for bridge and other transducer applica-
tions or ratiometric conversion with analog-to-digital con-
verters. A reference output of 2.5V, 5V or 10V is available
by connecting V
REF
OUT (pin 4) to one of the V
REF
pins
(V
REF
2.5, V
REF
5, or V
REF
10). Reference voltages are laser-
trimmed for low inital error and low temperature drift.
Connecting V
REF
OUT to V
REF
BG (pin 13) produces the
bandgap reference voltage (1.24V
±
0.5%) at the reference
output.
Positive supply voltage must be 1.25V above the desired
reference voltage. For example, with V+ = 2.7V, only the
1.24V reference (V
REF
BG) can be used. If using dual sup-
plies V
REF
COM can be connected to V–, increasing the
–
+
FIGURE 3. Providing an Input Common-Mode Current Path.
47k
47k
10k
Microphone,
Hydrophone
etc.
Thermocouple
Center-tap provides
bias current return.
INA125
INA125
INA125
–
相關(guān)PDF資料 |
PDF描述 |
|---|---|
| INA125U | Very High Accuracy Instrumentation Amplifier |
| INA125PA | Very High Accuracy Instrumentation Amplifier |
| INA126UA | Single Pole Normally Open: 1-Form-A |
| INA2126UA | Single Pole Normally Open: 1-Form-A |
| INA126PA | Micropower single-supply CMOS Instrumentation Amplifier |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| INA125P | 制造商:Texas Instruments 功能描述:IC AMP INSTRUMENTATION |
| INA125PA | 功能描述:儀表放大器 w/Precision Voltage Reference RoHS:否 制造商:Texas Instruments 通道數(shù)量: 輸入補(bǔ)償電壓:150 V 可用增益調(diào)整: 最大輸入電阻:10 kOhms 共模抑制比（最小值）:88 dB 工作電源電壓:2.7 V to 36 V 電源電流:200 uA 最大工作溫度:+ 125 C 最小工作溫度:- 40 C 封裝 / 箱體:MSOP-8 封裝:Bulk |
| INA125PA | 制造商:BURR-BROWN 功能描述:IC AMP INSTRUMENTATION DIP16 125 |
| INA125PA | 制造商:Texas Instruments 功能描述:Instrumentation Amplifier IC 制造商:Texas Instruments 功能描述:IC, INSTRUMENT AMP, 150KHZ, 114DB DIP-16 |
| INA125PAG4 | 功能描述:儀表放大器 w/Precision Voltage Reference RoHS:否 制造商:Texas Instruments 通道數(shù)量: 輸入補(bǔ)償電壓:150 V 可用增益調(diào)整: 最大輸入電阻:10 kOhms 共模抑制比（最小值）:88 dB 工作電源電壓:2.7 V to 36 V 電源電流:200 uA 最大工作溫度:+ 125 C 最小工作溫度:- 40 C 封裝 / 箱體:MSOP-8 封裝:Bulk |
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