參數(shù)資料
型號(hào)： AD7711
廠商： Analog Devices, Inc.
英文描述： LC2MOS Signal Conditioning ADC with RTD Excitation Currents(RTD激勵(lì)電流LC2MOS信號(hào)調(diào)節(jié)A/D轉(zhuǎn)換器)
中文描述： LC2MOS信號(hào)調(diào)理模數(shù)轉(zhuǎn)換器（RTD的激勵(lì)電流LC2MOS信號(hào)調(diào)節(jié)的A / D轉(zhuǎn)換器與RTD激勵(lì)電流）
文件頁(yè)數(shù)： 11/28頁(yè)
文件大?。?/td> 256K
代理商： AD7711
2
AD7711
–11–
REV. F
Tables I and II show the output rms noise for some typical notch and –3 dB frequencies. The numbers given are for the bipolar
input ranges with a V
REF
of +2.5 V. These numbers are typical and are generated with an analog input voltage of 0 V. The output
noise from the part comes from two sources. The first is the electrical noise in the semiconductor devices used in the implementation
of the modulator (device noise). The second occurs when the analog input signal is converted into the digital domain adding quanti-
zation noise. The device noise is at a low level and is largely independent of frequency. The quantization noise starts at an even
lower level but rises rapidly with increasing frequency to become the dominant noise source. Consequently, lower filter notch set-
tings (below 60 Hz approximately) tend to be device noise dominated while higher notch settings are dominated by quantization
noise. Changing the filter notch and cutoff frequency in the quantization noise dominated region results in a more dramatic im-
provement in noise performance than it does in the device noise dominated region as shown in Table I. Furthermore, quantization
noise is added after the PGA, so effective resolution is independent of gain for the higher filter notch frequencies. Meanwhile, device
noise is added in the PGA and, therefore, effective resolution suffers a little at high gains for lower notch frequencies.
At the lower filter notch settings (below 60 Hz), the no missing codes performance of the device is at the 24-bit level. At the higher
settings, more codes will be missed until at 1 kHz notch setting, no missing codes performance is only guaranteed to the 12-bit level.
However, since the effective resolution of the part is 10.5 bits for this filter notch setting, this no missing codes performance should
be more than adequate for all applications.
The effective resolution of the device is defined as the ratio of the output rms noise to the input full scale. This does not remain
constant with increasing gain or with increasing bandwidth. Table II shows the same table as Table I except that the output is now
expressed in terms of effective resolution (the magnitude of the rms noise with respect to 2
×
V
REF
/GAIN, i.e., the input full scale). It
is possible to do post filtering on the device to improve the output data rate for a given –3 dB frequency and also to further reduce
the output noise (see Digital Filtering section).
Table I. Output Noise vs. Gain and First Notch Frequency
First Notch of
Filter and O/P –3dB
Data Rate
1
Typical Output RMS Noise (
m
V)
Gain of
Gain of
4
8
Gain of
1
Gain of
2
Gain of
16
Gain of
32
Gain of
64
Gain of
128
Frequency
10Hz
2
25Hz
2
30Hz
2
50Hz
2
60Hz
2
100Hz
3
250Hz
3
500Hz
3
1kHz
3
2.62Hz
6.55Hz
7.86Hz
13.1 Hz
15.72 Hz
26.2 Hz
65.5 Hz
131 Hz
262 Hz
1.0
1.8
2.5
4.33
5.28
13
130
0.6
×
10
3
3.1
×
10
3
0.78
1.1
1.31
2.06
2.36
6.4
75
0.26
×
10
3
1.6
×
10
3
0.48
0.63
0.84
1.2
1.33
3.7
25
140
0.7
×
10
3
0.33
0.50
0.57
0.64
0.87
1.8
12
70
0.29
×
10
3
0.25
0.44
0.46
0.54
0.63
1.1
7.5
35
180
0.25
0.41
0.43
0.46
0.62
0.9
4
25
120
0.25
0.38
0.4
0.46
0.6
0.65
2.7
15
70
0.25
0.38
0.4
0.46
0.56
0.65
1.7
8
40
NOTES
1
The default condition (after the internal power-on reset) for the first notch of filter is 60 Hz.
2
For these filter notch frequencies, the output rms noise is primarily dominated by device noise and as a result is independent of the value of the reference voltage.
Therefore, increasing the reference voltage will give an increase in the effective resolution of the device (i.e., the ratio of the rms noise to the input full scale is in-
creased since the output rms noise remains constant as the input full scale increases).
3
For these filter notch frequencies, the output rms noise is dominated by quantization noise and as a result is proportional to the value of the reference voltage.
Table II. Effective Resolution vs. Gain and First Notch Frequency
First Notch of
Filter and O/P –3dB
Data Rate
Effective Resolution
1
(Bits)
Gain of
Gain of
4
8
Gain of
1
Gain of
2
Gain of
16
Gain of
32
Gain of
64
Gain of
128
Frequency
10Hz
25Hz
30Hz
50Hz
60Hz
100Hz
250Hz
500Hz
1kHz
2.62Hz
6.55Hz
7.86Hz
13.1Hz
15.72Hz
26.2Hz
65.5Hz
131Hz
262Hz
22.5
21.5
21
20
20
18.5
15
13
10.5
21.5
21
21
20
20
18.5
15
13
10.5
21.5
21
20.5
20
20
18.5
15.5
13
11
21
20
20
20
19.5
18.5
15.5
13
11
20.5
19.5
19.5
19
19
18
15.5
13
11
19.5
18.5
18.5
18.5
18
17.5
15.5
12.5
10.5
18.5
17.5
17.5
17.5
17
17
15
12.5
10
17.5
16.5
16.5
16.5
16
16
14.5
12.5
10
NOTE
1
Effective resolution is defined as the magnitude of the output rms noise with respect to the input full scale (i.e., 2
×
V
REF
/GAIN). The above table applies for
a V
REF
of +2.5 V and resolution numbers are rounded to the nearest 0.5 LSB.
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AD7711A 制造商:AD 制造商全稱:Analog Devices 功能描述:LC2MOS Signal Conditioning ADC with RTD Current Source
AD7711AAN 制造商:未知廠家 制造商全稱:未知廠家 功能描述:Analog-to-Digital Converter， 24-Bit
AD7711AAR 功能描述:IC ADC 24BIT RTD I SOURCE 24SOIC RoHS:否 類別:集成電路 (IC) >> 數(shù)據(jù)采集 - 模數(shù)轉(zhuǎn)換器 系列:- 標(biāo)準(zhǔn)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(zhuǎn)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(yīng)商設(shè)備封裝:28-PDIP 包裝:管件 輸入數(shù)目和類型:1 個(gè)單端，雙極
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