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參數(shù)資料
| 型號： | AD7712 |
| 廠商： | Analog Devices, Inc. |
| 英文描述： | Signal Conditioning ADC(LC2MOS信號調節(jié)A/D轉換器) |
| 中文描述： | 信號調理模數(shù)轉換器（LC2MOS信號調節(jié)的A / D轉換器） |
| 文件頁數(shù)： | 15/28頁 |
| 文件大小： | 242K |
| 代理商： | AD7712 |
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2
–15–
REV. E
AD7712
Table IV. Typical External Series Resistance That Will Not
Introduce 16-Bit Gain Error
External Capacitance (pF)
50
100
45.3 k
27.1 k
7.3 k
88.6 k
22.1 k
13.2 k
3.6 k
41.4 k
10.6 k
6.3 k
17.6 k
4.8 k
Gain
0
184 k
500
1000
4.1 k
2.0 k
970
440
5000
1.1 k
560
270
120
1
2
4
8–128
1.7 k
790
2.9 k
Table V. Typical External Series Resistance That Will Not
Introduce 20-Bit Gain Error
External Capacitance (pF)
50
100
34.5 k
20.4 k
5.2 k
70.5 k
16.9 k
10 k
31.8 k
8.0 k
13.4 k
3.6 k
Gain
0
145 k
500
1000
2.8 k
1.4 k
670
300
5000
700
350
170
80
1
2
4
8–128
2.5 k
1.2 k
550
4.8 k
2.2 k
The numbers in the above tables assume a full-scale change on
the analog input. In any case, the error introduced due to longer
charging times is a gain error which can be removed using the
system calibration capabilities of the AD7712 provided that the
resultant span is within the span limits of the system calibration
techniques for the AD7712.
The AIN2 input contains a resistive attenuation network as
outlined in Figure 8. The typical input impedance on this input
is 44 k
. As a result, the AIN2 input should be driven from a
low impedance source.
33k
V
V
BIAS
AIN2
11k
V
MODULATOR
CIRCUIT
Figure 8. AIN2 Input Impedance
Antialias Considerations
The digital filter does not provide any rejection at integer mul-
tiples of the modulator sample frequency (n
×
19.5 kHz, where
n = 1, 2, 3 . . . ). This means that there are frequency bands,
±
f
3 dB
wide (f
3 dB
is cutoff frequency selected by FS0 to FS11)
where noise passes unattenuated to the output. However, due to
the AD7712’s high oversampling ratio, these bands occupy only
a small fraction of the spectrum and most broadband noise is
filtered. In any case, because of the high oversampling ratio a
simple, RC, single pole filter is generally sufficient to attenuate
the signals in these bands on the analog input and thus provide
adequate antialiasing filtering.
If passive components are placed in front of the AIN1 input of
the AD7712, care must be taken to ensure that the source imped-
ance is low enough so as not to introduce gain errors in the sys-
tem. The dc input impedance for the AIN1 input is over 1 G
.
The input appears as a dynamic load that varies with the clock
frequency and with the selected gain (see Figure 7). The input
sample rate, as shown in Table III, determines the time allowed
for the analog input capacitor, C
IN
, to be charged. External
impedances result in a longer charge time for this capacitor, and
this may result in gain errors being introduced on the analog
inputs. Table IV shows the allowable external resistance/
capacitance values such that no gain error to the 16-bit level
is introduced while Table V shows the allowable external
resistance/capacitance values such that no gain error to the
20-bit level is introduced. Both inputs of the differential input
channels (AIN1) look into similar input circuitry.
R
INT
(7k
V
TYP)
C
INT
(11.5pF TYP)
V
BIAS
AIN
SWITCHING FREQUENCY DEPENDS ON
f
CLKIN
AND SELECTED GAIN
HIGH
IMPEDANCE
>1G
V
Figure 7. AIN1 Input Impedance
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相關代理商/技術參數(shù) |
參數(shù)描述 |
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| AD7712_04 | 制造商:AD 制造商全稱:Analog Devices 功能描述:LC2MOS Signal Conditioning ADC |
| AD7712AN | 功能描述:IC ADC SIGNAL COND LC2MOS 24-DIP RoHS:否 類別:集成電路 (IC) >> 數(shù)據(jù)采集 - 模數(shù)轉換器 系列:- 標準包裝:1 系列:- 位數(shù):14 采樣率（每秒）:83k 數(shù)據(jù)接口:串行，并聯(lián) 轉換器數(shù)目:1 功率耗散（最大）:95mW 電壓電源:雙 ± 工作溫度:0°C ~ 70°C 安裝類型:通孔 封裝/外殼:28-DIP（0.600"，15.24mm） 供應商設備封裝:28-PDIP 包裝:管件 輸入數(shù)目和類型:1 個單端，雙極 |
| AD7712ANZ | 功能描述:IC ADC SIGNAL COND LC2MOS 24-DIP RoHS:是 類別:集成電路 (IC) >> 數(shù)據(jù)采集 - 模數(shù)轉換器 系列:- 其它有關文件:TSA1204 View All Specifications 標準包裝:1 系列:- 位數(shù):12 采樣率（每秒）:20M 數(shù)據(jù)接口:并聯(lián) 轉換器數(shù)目:2 功率耗散（最大）:155mW 電壓電源:模擬和數(shù)字 工作溫度:-40°C ~ 85°C 安裝類型:表面貼裝 封裝/外殼:48-TQFP 供應商設備封裝:48-TQFP（7x7） 包裝:Digi-Reel® 輸入數(shù)目和類型:4 個單端，單極；2 個差分，單極 產品目錄頁面:1156 (CN2011-ZH PDF) 其它名稱:497-5435-6 |
| AD7712ANZ | 制造商:Analog Devices 功能描述:IC ADC 24-BIT SIGMA DELTA |
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