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參數(shù)資料
| 型號： | AD7711* |
| 廠商： | Analog Devices, Inc. |
| 英文描述： | LC2MOS Signal Conditioning ADC with RTD Excitation Currents |
| 中文描述： | LC2MOS信號調(diào)理型ADC RTD激勵電流 |
| 文件頁數(shù)： | 19/28頁 |
| 文件大小： | 242K |
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2
AD7711
–19–
REV. F
POWER-UP AND CALIBRATION
On power-up, the AD7711 performs an internal reset which sets
the contents of the control register to a known state. However,
to ensure correct calibration for the device a calibration routine
should be performed after power-up.
The power dissipation and temperature drift of the AD7711 are
low and no warm up time is required before the initial calibra-
tion is performed. However, if an external reference is being
used, this reference must have stabilized before calibration is
initiated.
Drift Considerations
The AD7711 uses chopper stabilization techniques to minimize
input offset drift. Charge injection in the analog switches and dc
leakage currents at the sampling node are the primary sources of
offset voltage drift in the converter. The dc input leakage cur-
rent is essentially independent of the selected gain. Gain drift
within the converter depends primarily upon the temperature
tracking of the internal capacitors. It is not affected by leakage
currents.
Measurement errors due to offset drift or gain drift can be elimi-
nated at any time by recalibrating the converter or by operating
the part in the background calibration mode. Using the system
calibration mode can also minimize offset and gain errors in the
signal conditioning circuitry. Integral and differential linearity
errors are not significantly affected by temperature changes.
POWER SUPPLIES AND GROUNDING
Since the analog inputs and reference input are differential,
most of the voltages in the analog modulator are common-mode
voltages. V
BIAS
provides the return path for most of the analog
currents flowing in the analog modulator. As a result, the V
BIAS
input should be driven from a low impedance to minimize errors
due to charging/discharging impedances on this line. When the
internal reference is used as the reference source for the part,
AGND is the ground return for this reference voltage.
The analog and digital supplies to the AD7711 are independent
and separately pinned out to minimize coupling between the
analog and digital sections of the device. The digital filter will
provide rejection of broadband noise on the power supplies,
except at integer multiples of the modulator sampling frequency.
The digital supply (DV
DD
) must not exceed the analog positive
supply (AV
DD
) by more than 0.3 V in normal operation. If sepa-
rate analog and digital supplies are used, the recommended
decoupling scheme is shown in Figure 9. In systems where
AV
DD
= +5 V and DV
DD
= +5 V, it is recommended that AV
DD
and DV
DD
are driven from the same +5 V supply, although each
supply should be decoupled separately as shown in Figure 9. It
is preferable that the common supply is the system’s analog +5 V
supply.
It is also important that power is applied to the AD7711 before
signals at REF IN, AIN or the logic input pins in order to avoid
latch-up. If separate supplies are used for the AD7711 and the
system digital circuitry, then the AD7711 should be powered up
first. If it is not possible to guarantee this, then current limiting
resistors should be placed in series with the logic inputs.
AD7711
AV
DD
DV
DD
0.1
m
F
10
m
F
ANALOG
SUPPLY
0.1
m
F
DIGITAL +5V
SUPPLY
Figure 9. Recommended Decoupling Scheme
相關(guān)PDF資料 |
PDF描述 |
|---|---|
| AD7711A | Signal Conditioning ADC with RTD Current Source(帶RTD電流源信號調(diào)節(jié)A/D轉(zhuǎn)換器) |
| AD7711 | LC2MOS Signal Conditioning ADC with RTD Excitation Currents(RTD激勵電流LC2MOS信號調(diào)節(jié)A/D轉(zhuǎn)換器) |
| AD7714(中文) | Signal Conditioning ADC(信號調(diào)節(jié)A/D轉(zhuǎn)換器) |
| AD7715 | 3 V/5 V, 450 mA 16-Bit, Sigma-Delta ADC(16位∑△A/D轉(zhuǎn)換器) |
| AD7716BP | LC2MOS 22-Bit Data Acquisition System |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| 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 個單端，雙極 |
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