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參數(shù)資料
| 型號(hào)： | INA327 |
| 元件分類(lèi)： | 測(cè)量放大器 |
| 英文描述： | Precision. Low Drift. CMOS Instrumentation Amplifier with Shutdown |
| 中文描述： | 精密。低漂移。的CMOS儀表放大器具有關(guān)斷 |
| 文件頁(yè)數(shù)： | 9/15頁(yè) |
| 文件大?。?/td> | 270K |
| 代理商： | INA327 |
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INA326, INA327
SBOS222
9
www.ti.com
Following this design procedure for R
1
produces the maxi-
mum possible input stage gain for best accuracy and lowest
noise.
Circuit layout and supply bypassing can affect performance.
Minimize the stray capacitance on pins 1 and 8. Use recom-
mended supply bypassing, including a capacitor directly from
pin 7 to pin 4 (V+ to V
–
), even with dual (split) power supplies
(see Figure 1).
DYNAMIC PERFORMANCE
The typical characteristic
“
Gain vs Frequency
”
shows that the
INA326 has nearly constant bandwidth regardless of gain.
This results from the bandwidth limiting from the recom-
mended filters.
NOISE PERFORMANCE
Internal auto-correction circuitry eliminates virtually all 1/f
noise (noise that increases at low frequency) in gains of 100
or greater. Noise performance is affected by gain-setting
resistor values. Follow recommendations in the
“
Setting
Gain
”
section for best performance.
Total noise is a combination of input stage noise and output
stage noise. When referred to the input, the total mid-band
noise is:
V
nV
Hz
nV
Hz
G
N
=
+
44
800
/
/
(3)
The output noise has some 1/f components that affect
performance in gains less than 10. See typical characteristic
“
Input-Referred Voltage Noise vs Frequency.
”
High-frequency noise is created by internal auto-correction
circuitry and is highly dependent on the filter characteristics
chosen. This may be the dominant source of noise visible
when viewing the output on an oscilloscope. Low cutoff
frequency filters will provide lowest noise. Figure 2 shows the
typical noise performance as a function of cutoff frequency.
Applications sensitive to the spectral characteristics of high-
frequency noise may require consideration of the spurious
frequencies generated by internal clocking circuitry.
“
Spurs
”
occur at approximately 90kHz and its harmonics (see typical
characteristic
“
Output Spectrum
”
) which may be reduced by
additional filtering below 1kHz.
Insufficient filtering at pin 5 can cause nonlinearity with large
output voltage swings (very near the supply rails). Noise
must be sufficiently filtered at pin 5 so that noise peaks do not
“
hit the rail
”
and change the average value of the signal.
Figure 2 shows guidelines for filter cutoff frequency.
HIGH-FREQUENCY NOISE
C
2
and C
O
form filters to reduce internally generated auto-
correction circuitry noise. Filter frequencies can be chosen to
optimize the tradeoff between noise and frequency response
of the application, as shown in Figure 2. The cutoff frequen-
cies of the filters are generally set to the same frequency.
Figure 2 shows the typical output noise for four gains as a
function of the
–
3dB cutoff frequency of the combined two-
pole response. This is equal to the
–
1.5dB response fre-
quency of each of the 1-pole filters. Small signals may exhibit
the addition of internally generated auto-correction circuitry
noise at the output. This noise, combined with broadband
noise, becomes most evident in higher gains with filters of
wider bandwidth.
INPUT BIAS CURRENT RETURN PATH
The input impedance of the INA326 is extremely high
—
approximately 10
10
. However, a path must be provided for
the input bias current of both inputs. This input bias current is
approximately
±
0.2nA. 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 provision for an input
bias current path in a thermocouple application. Without a
bias current path, the inputs will float to an undefined poten-
tial and the output voltage may not be valid.
FIGURE 2. Total Output Noise vs Filter Cutoff Frequency.
TOTAL OUTPUT NOISE
vs FILTER CUTOFF FREQUENCY
100
1
10
1k
10k
Required Filter Cutoff Frequency (Hz)
T
μ
V
R
)
1k
100
10
1
G = 10
G = 1
G = 100
G = 1000
INA326
Thermocouple
5
FIGURE 3. Providing Input Bias Current Return Path.
相關(guān)PDF資料 |
PDF描述 |
|---|---|
| INA327IDGSR | INSTRUMENTATION AMPLIFIER|SINGLE|CMOS|TSSOP|10PIN|PLASTIC |
| INA327IDGST | INSTRUMENTATION AMPLIFIER|SINGLE|CMOS|TSSOP|10PIN|PLASTIC |
| INA330 | THERMISTOR SIGNAL AMPLIFIER FOR TEMPERATURE CONTROL |
| INA330AIDGSR | THERMISTOR SIGNAL AMPLIFIER FOR TEMPERATURE CONTROL |
| INA330AIDGST | THERMISTOR SIGNAL AMPLIFIER FOR TEMPERATURE CONTROL |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| INA327EA | 制造商:Texas Instruments 功能描述:AMP INSTRUMENTATION VSSOP10 327 |
| INA327EA/250 | 功能描述:儀表放大器 Precision Lo-Drift CMOS w/Shutdown 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 |
| INA327EA/250G4 | 功能描述:儀表放大器 Precision Lo-Drift CMOS w/Shutdown 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 |
| INA327EA/2K5 | 功能描述:儀表放大器 Precision Lo-Drift CMOS w/Shutdown 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 |
| INA327EA/2K5G4 | 功能描述:儀表放大器 Precision Lo-Drift CMOS w/Shutdown 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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