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參數(shù)資料
| 型號： | AD7939BSU |
| 廠商： | ANALOG DEVICES INC |
| 元件分類： | ADC |
| 英文描述： | 8-Channel, 1.5 MSPS, 12-Bit and 10-Bit Parallel ADCs with a Sequencer |
| 中文描述： | 8-CH 10-BIT SUCCESSIVE APPROXIMATION ADC, PARALLEL ACCESS, PQFP32 |
| 封裝： | PLASTIC, MS-026-ABA, TQFP-32 |
| 文件頁數(shù)： | 31/32頁 |
| 文件大小： | 1332K |
| 代理商： | AD7939BSU |
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Preliminary Technical Data
AD7938/AD7939
APPLICATION HINTS
GROUNDING AND LAYOUT
The printed circuit board that houses the AD7938/AD7939
should be designed so that the analog and digital sections are
separated and confined to certain areas of the board. This
facilitates the use of ground planes that can be easily separated.
A minimum etch technique is generally best for ground planes
as it gives the best shielding. Digital and analog ground planes
should be joined in only one place, and the connection should
be a star ground point established as close to the ground pins on
the AD7938/AD7939 as possible. Avoid running digital lines
under the device as this will couple noise onto the die. The
analog ground plane should be allowed to run under the
AD7938/AD7939 to avoid noise coupling. The power supply
lines to the AD7938/AD7939 should use as large a trace as
possible to provide low impedance paths and reduce the effects
of glitches on the power supply line.
Fast switching signals, such as clocks, should be shielded with
digital ground to avoid radiating noise to other sections of the
board, and clock signals should never run near the analog
inputs. Avoid crossover of digital and analog signals. Traces on
opposite sides of the board should run at right angles to each
other. This will reduce the effects of feedthrough through the
board. A microstrip technique is by far the best but is not always
possible with a double-sided board.
In this technique, the component side of the board is dedicated
to ground planes, while signals are placed on the solder side.
Good decoupling is also important. All analog supplies should
be decoupled with 10 μF tantalum capacitors in parallel with
0.1 μF capacitors to GND. To achieve the best from these
decoupling components, they must be placed as close as
possible to the device, ideally right up against the device. The
0.1 μF capacitors should have low effective series resistance
(ESR) and effective series inductance (ESI), such as the
common ceramic types or surface-mount types, which provide
a low impedance path to ground at high frequencies to handle
transient currents due to internal logic switching.
PCB DESIGN GUIDELINES FOR CHIP SCALE
PACKAGE
The lands on the chip scale package (CP-32) are rectangular.
The printed circuit board pad for these should be 0.1 mm
longer than the package land length and 0.05 mm wider than
the package land width. The land should be centered on the pad.
This ensures that the solder joint size is maximized. The bottom
of the chip scale package has a thermal pad. The thermal pad on
the printed circuit board should be at least as large as this
exposed pad. On the printed circuit board, there should be a
clearance of at least 0.25 mm between the thermal pad and the
inner edges of the pad pattern. This ensures that shorting is
avoided. Thermal vias may be used on the printed circuit board
thermal pad to improve thermal performance of the package. If
vias are used, they should be incorporated in the thermal pad at
1.2 mm pitch grid. The via diameter should be between 0.3 mm
and 0.33 mm, and the via barrel should be plated with 1 oz.
copper to plug the via. The user should connect the printed
circuit board thermal pad to AGND.
EVALUATING THE AD7938/AD7939
PERFORMANCE
The recommended layout for the AD7938/AD7939 is outlined
in the evaluation board documentation. The evaluation board
package includes a fully assembled and tested evaluation board,
documentation, and software for controlling the board from the
PC via the evaluation board controller. The evaluation board
controller can be used in conjunction with the
AD7938/AD7939 evaluation board, as well as many other ADI
evaluation boards ending in the CB designator, to
demonstrate/evaluate the ac and dc performance of the
AD7938/AD7939.
The software allows the user to perform ac (fast Fourier
transform) and dc (histogram of codes) tests on the
AD7938/AD7939. The software and documentation are on the
CD that ships with the evaluation board.
Rev. PrN | Page 31 of 32
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相關代理商/技術參數(shù) |
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| AD7939BSU-REEL | 制造商:Analog Devices 功能描述: |
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| AD7939BSUZ | 功能描述:IC ADC 10BIT 8CH PARALL 32TQFP 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(chǎn)品目錄頁面:1156 (CN2011-ZH PDF) 其它名稱:497-5435-6 |
| AD7939BSUZ-REEL7 | 功能描述:IC ADC 10BIT 8CH PARALL 32TQFP RoHS:是 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:1,000 系列:- 位數(shù):16 采樣率（每秒）:45k 數(shù)據(jù)接口:串行 轉換器數(shù)目:2 功率耗散（最大）:315mW 電壓電源:模擬和數(shù)字 工作溫度:0°C ~ 70°C 安裝類型:表面貼裝 封裝/外殼:28-SOIC（0.295"，7.50mm 寬） 供應商設備封裝:28-SOIC W 包裝:帶卷 (TR) 輸入數(shù)目和類型:2 個單端，單極 |
| AD7940 | 制造商:AD 制造商全稱:Analog Devices 功能描述:3mW, 100kSPS, 14-Bit ADC in 6-Lead SOT-23 |
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