參數資料
| 型號： | AD8230YRZ-REEL |
| 廠商： | Analog Devices Inc |
| 文件頁數： | 3/16頁 |
| 文件大?。?/td> | 0K |
| 描述： | IC AMP CHOPPER R-R PREC 8SOIC |
| 標準包裝： | 2,500 |
| 放大器類型： | 斷路器（零漂移） |
| 電路數： | 1 |
| 輸出類型： | 滿擺幅 |
| 轉換速率： | 2 V/µs |
| 電流 - 輸入偏壓： | 150pA |
| 電壓 - 輸入偏移： | 20µV |
| 電流 - 電源： | 3.2mA |
| 電流 - 輸出 / 通道： | 15mA |
| 電壓 - 電源，單路/雙路(±)： | 8 V ~ 16 V，±4 V ~ 8 V |
| 工作溫度： | -40°C ~ 125°C |
| 安裝類型： | 表面貼裝 |
| 封裝/外殼： | 8-SOIC（0.154"，3.90mm 寬） |
| 供應商設備封裝： | 8-SO |
| 包裝： | 帶卷 (TR) |
AD8230
Rev. B | Page 11 of 16
THEORY OF OPERATION
Auto-zeroing is a dynamic offset and drift cancellation
technique that reduces input-referred voltage offset to the
μV level and voltage offset drift to the nV/°C level. A further
advantage of dynamic offset cancellation is the reduction of
low frequency noise, in particular the 1/f component.
The AD8230 is an instrumentation amplifier that uses an
auto-zeroing topology and combines it with high common-
mode signal rejection. The internal signal path consists of an
active differential sample-and-hold stage (preamp) followed by
a differential amplifier (gain amp). Both amplifiers implement
auto-zeroing to minimize offset and drift. A fully differential
topology increases the immunity of the signals to parasitic noise
and temperature effects. Amplifier gain is set by two external
resistors for convenient TC matching.
The signal sampling rate is controlled by an on-chip, 6 kHz
oscillator and logic to derive the required nonoverlapping
clock phases. For simplification of the functional description,
two sequential clock phases, A and B, are shown to distinguish
the order of internal operation, as depicted in Figure 30 and
Figure 31, respectively.
–
– +
+
VREF
CHOLD
VOUT
V+IN
V–IN
CHOLD
CSAMPLE
RF
RG
PREAMP
GAIN AMP
VDIFF
+VCM
–VS
05
06
3-
03
0
Figure 30. Phase A of the Sampling Phase
During Phase A, the sampling capacitors are connected to the
inputs. The input signal’s difference voltage, VDIFF, is stored
across the sampling capacitors, CSAMPLE. Because the sampling
capacitors only retain the difference voltage, the common-mode
voltage is rejected. During this period, the gain amplifier is not
connected to the preamplifier so its output remains at the level
set by the previously sampled input signal held on CHOLD, as
shown in Figure 30.
–
– +
+
VREF
CHOLD
VOUT
V+IN
V–IN
CHOLD
CSAMPLE
RF
RG
PREAMP
GAIN AMP
VDIFF
+VCM
–VS
05
06
3-
03
1
Figure 31. Phase B of the Sampling Phase
In Phase B, the differential signal is transferred to the hold
capacitors refreshing the value stored on CHOLD. The output of
the preamplifier is held at a common-mode voltage determined
by the reference potential, VREF. In this manner, the AD8230 is
able to condition the difference signal and set the output voltage
level. The gain amplifier conditions the updated signal stored
on the hold capacitors, CHOLD.
SETTING THE GAIN
Two external resistors set the gain of the AD8230. The gain is
expressed in the following equation:
)
2(1
G
F
R
Gain
+
=
(1)
2
6
1
7
5
8
4
3
AD8230
VOUT
–VS
+VS
0.1F
RG
RF
RG
VREF1
VREF2
0.1F
10F
05
06
3-
0
32
Figure 32. Gain Setting
Table 5. Gains Using Standard 1% Resistors
Gain
RF
RG
Actual Gain
2
0 Ω (short)
None
2
10
8.06 kΩ
2 kΩ
10
50
12.1 kΩ
499 Ω
50.5
100
9.76 kΩ
200 Ω
99.6
200
10 kΩ
100 Ω
202
500
49.9 kΩ
200 Ω
501
1000
100 kΩ
200 Ω
1002
As Table 5 shows, the AD8230 accepts a wide range of resistor
values. Because the instrumentation amplifier has finite driving
capability, ensure that the output load in parallel with the sum
of the gain setting resistors is greater than 2 kΩ.
RL
||(RF + RG) > 2 kΩ
(2)
Offset voltage drift at high temperature can be minimized by
keeping the value of the feedback resistor, RF, small. This is due
to the junction leakage current on the RG pin, Pin 7. The effect
of the gain setting resistor on offset voltage drift is shown in
Figure 33. In addition, experience has shown that wire-wound
resistors in the gain feedback loop may degrade the offset
voltage performance.
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| AD8230YRZ-REEL7 | 功能描述:IC AMP CHOPPER R-R PREC 8SOIC RoHS:是 類別:集成電路 (IC) >> Linear - Amplifiers - Instrumentation 系列:- 標準包裝:1 系列:- 放大器類型:通用 電路數:4 輸出類型:滿擺幅 轉換速率:0.028 V/µs 增益帶寬積:105kHz -3db帶寬:- 電流 - 輸入偏壓:3nA 電壓 - 輸入偏移:100µV 電流 - 電源:3.3µA 電流 - 輸出 / 通道:12mA 電壓 - 電源，單路/雙路(±):2.7 V ~ 12 V，±1.35 V ~ 6 V 工作溫度:-40°C ~ 85°C 安裝類型:表面貼裝 封裝/外殼:14-TSSOP（0.173"，4.40mm 寬） 供應商設備封裝:14-TSSOP 包裝:剪切帶 (CT) 其它名稱:OP481GRUZ-REELCT |
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