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參數(shù)資料
| 型號： | ADS8344 |
| 英文描述： | 16-Bit, 8-Channel Serial Output Sampling ANALOG-TO-DIGITAL CONVERTER |
| 中文描述： | 16位，8通道串行輸出采樣模擬到數(shù)字轉換器 |
| 文件頁數(shù)： | 13/13頁 |
| 文件大?。?/td> | 278K |
| 代理商： | ADS8344 |
13
ADS8344
FIGURE 9. Histogram of 5000 Conversions of a DC Input at the
Code Center, 5V operation internal clock mode.
Code
4507
251
0
0
242
7FFE
7FFD
8001
8000
7FFF
FIGURE 10. Histogram of 5000 Conversions of a DC Input at the
Code Transition, 2.7V operation external clock mode.
FIGURE 11. Histogram of 5000 Conversions of a DC Input at the
Code Center, 2.7V operation internal clock mode.
Code
3511
721
666
50
52
7FFE
7FFD
8001
8000
7FFF
Code
2868
1137
858
78
59
7FFE
7FFD
8001
8000
7FFF
sion results will reduce the transition noise by 1/2 to
±
0.25
LSBs. Averaging should only be used for input signals with
frequencies near DC.
For AC signals, a digital filter can be used to low pass filter
and decimate the output codes. This works in a similar
manner to averaging; for every decimation by 2, the signal-
to-noise ratio will improve 3dB.
LAYOUT
For optimum performance, care should be taken with the
physical layout of the ADS8344 circuitry. This is particu-
larly true if the reference voltage is low and/or the conver-
sion rate is high.
The basic SAR architecture is sensitive to glitches or sudden
changes on the power supply, reference, ground connec-
tions, and digital inputs that occur just prior to latching the
output of the analog comparator. Thus, during any single
conversion for an n-bit SAR converter, there are n “win-
dows” in which large external transient voltages can easily
affect the conversion result. Such glitches might originate
from switching power supplies, nearby digital logic, and
high power devices. The degree of error in the digital output
depends on the reference voltage, layout, and the exact
timing of the external event. The error can change if the
external event changes in time with respect to the DCLK
input.
With this in mind, power to the ADS8344 should be clean
and well bypassed. A 0.1
μ
F ceramic bypass capacitor should
be placed as close to the device as possible. In addition, a
1
μ
F to 10
μ
F capacitor and a 5
or 10
series resistor may
be used to lowpass filter a noisy supply.
The reference should be similarly bypassed with a 0.1
μ
F
capacitor. Again, a series resistor and large capacitor can be
used to lowpass filter the reference voltage. If the reference
voltage originates from an op amp, make sure that it can
drive the bypass capacitor without oscillation (the series
resistor can help in this case). The ADS8344 draws very
little current from the reference on average, but it does place
larger demands on the reference circuitry over short periods
of time (on each rising edge of DCLK during a conversion).
The ADS8344 architecture offers no inherent rejection of
noise or voltage variation in regards to the reference input.
This is of particular concern when the reference input is tied
to the power supply. Any noise and ripple from the supply
will appear directly in the digital results. While high fre-
quency noise can be filtered out as discussed in the previous
paragraph, voltage variation due to line frequency (50Hz or
60Hz) can be difficult to remove.
The GND pin should be connected to a clean ground point.
In many cases, this will be the “analog” ground. Avoid
connections which are too near the grounding point of a
microcontroller or digital signal processor. If needed, run a
ground trace directly from the converter to the power supply
entry point. The ideal layout will include an analog ground
plane dedicated to the converter and associated analog
circuitry.
AVERAGING
The noise of the A/D converter can be compensated by
averaging the digital codes. By averaging conversion results,
transition noise will be reduced by a factor of 1/
√
n, where n
is the number of averages. For example, averaging 4 conver-
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相關代理商/技術參數(shù) |
參數(shù)描述 |
|---|---|
| ADS8344E | 功能描述:模數(shù)轉換器 - ADC 16-Bit 8-Ch Serial Output Sampling RoHS:否 制造商:Texas Instruments 通道數(shù)量:2 結構:Sigma-Delta 轉換速率:125 SPs to 8 KSPs 分辨率:24 bit 輸入類型:Differential 信噪比:107 dB 接口類型:SPI 工作電源電壓:1.7 V to 3.6 V, 2.7 V to 5.25 V 最大工作溫度:+ 85 C 安裝風格:SMD/SMT 封裝 / 箱體:VQFN-32 |
| ADS8344E | 制造商:Texas Instruments 功能描述:IC's |
| ADS8344E | 制造商:Texas Instruments 功能描述:16BIT ADC SERIAL O/P SMD 8344 |
| ADS8344E/2K5 | 功能描述:模數(shù)轉換器 - ADC 16-Bit 8-Ch Serial Output Sampling RoHS:否 制造商:Texas Instruments 通道數(shù)量:2 結構:Sigma-Delta 轉換速率:125 SPs to 8 KSPs 分辨率:24 bit 輸入類型:Differential 信噪比:107 dB 接口類型:SPI 工作電源電壓:1.7 V to 3.6 V, 2.7 V to 5.25 V 最大工作溫度:+ 85 C 安裝風格:SMD/SMT 封裝 / 箱體:VQFN-32 |
| ADS8344E/2K5G4 | 功能描述:模數(shù)轉換器 - ADC 16-Bit 8-Ch Serial Output Sampling RoHS:否 制造商:Texas Instruments 通道數(shù)量:2 結構:Sigma-Delta 轉換速率:125 SPs to 8 KSPs 分辨率:24 bit 輸入類型:Differential 信噪比:107 dB 接口類型:SPI 工作電源電壓:1.7 V to 3.6 V, 2.7 V to 5.25 V 最大工作溫度:+ 85 C 安裝風格:SMD/SMT 封裝 / 箱體:VQFN-32 |
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