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參數(shù)資料
| 型號： | AD668SQ |
| 廠商： | ANALOG DEVICES INC |
| 元件分類： | DAC |
| 英文描述： | 12-Bit Ultrahigh Speed Multiplying D/A Converter |
| 中文描述： | PARALLEL, WORD INPUT LOADING, 0.12 us SETTLING TIME, 12-BIT DAC, CDIP24 |
| 封裝： | 0.300 INCH, SKINNY, CERDIP-24 |
| 文件頁數(shù)： | 11/16頁 |
| 文件大?。?/td> | 602K |
| 代理商： | AD668SQ |
AD668
REV. A
–11–
reference input. While the two DACs are similar in many ways,
the optimal decoupling schemes differ between the two parts
and care should be used to insure that each is implemented
appropriately.
Figure 13. AD568 Driving the AD668
CONSTRUCTION GUIDELINES
HIGH FREQUENCY PRINTED CIRCUIT BOARD
SUGGESTIONS
In systems seeking to simultaneously achieve high speed and
high accuracy, the implementation and construction of the cir-
cuit is often as important as the circuit’s design. Proper RF
techniques must be used in device selection, placement and
routing, and supply bypassing and grounding. In many areas,
the performance of the AD668 may exceed the measurement ca-
pabilities of common lab instruments, making performance
evaluation particularly difficult. The AD668 has been config-
ured to be relatively easy to use in spite of these problems, and
realization of the performance indicated in this datasheet should
not be difficult if proper care is taken. Figure 14 provides an il-
lustration of the printed circuit board layout used for much of
the AD668’s characterization. The board represents an imple-
mentation of the circuit shown in Figure 23, with the AD586
used to drive the reference channel (as in Figure 11).
Component Side
Foil Side
Figure 14. PC Board Layout
THE USE OF GROUND AND POWER PLANES
If properly implemented, ground planes can perform a myriad
of functions on high speed circuit boards: bypassing, shielding,
current transport, etc. In mixed signal design, the analog and
digital portions of the board should be distinct from one an-
other, with the analog ground plane confined to areas covering
analog signal traces and the digital ground plane confined to
areas covering digital interconnect. The two ground planes
should be connected by paths 1/4 inch to 1/2 inch wide on both
sides of the DAC, as shown in Figure 14. Care should be taken
to insure that the ground plane is uninterrupted over crucial sig-
nal paths. On the digital side, this includes the digital input lines
running to the DAC, as well as any clock signals. On the analog
side, this includes the analog input signal, the DAC output sig-
nal, and the supply feeders. The use of wide runs or planes in
the routing of the power supplies is also recommended. This
serves the dual function of providing a low series impedance
power supply to the part as well as providing some “free” ca-
pacitive decoupling to the appropriate ground plane.
USING THE RIGHT BYPASS CAPACITORS
The capacitors used to bypass the power supplies are probably
the most important external components in any high speed de-
sign. Both selection and placement of these capacitors can be
critical and, to a large extent, dependent upon the specifics of
the system configuration. The dominant consideration in the
selection of bypass capacitors for the AD668 is minimization of
series resistance and inductance. Many capacitors will begin to
look inductive at 20 MHz and above. Ceramic and film type
capacitors generally feature lower series inductance than tanta-
lum or electrolytic types. A few general rules are of universal use
when approaching the problem of bypassing.
Bypass capacitors should be installed on the printed circuit
board with the shortest possible leads consistent with reliable
construction. This helps to minimize series inductance in the
leads. Chip capacitors are optimal in this respect.
Some series inductance between the DAC supply pins and the
power supply plane may help to filter-out high frequency power
supply noise. This inductance can be generated using a small
ferrite bead.
相關(guān)PDF資料 |
PDF描述 |
|---|---|
| AD668 | 12-Bit Ultrahigh Speed Multiplying D/A Converter |
| AD668JQ | 12-Bit Ultrahigh Speed Multiplying D/A Converter |
| AD669AN | Monolithic 16-Bit DACPORT |
| AD669AQ | Monolithic 16-Bit DACPORT |
| AD669AR | Monolithic 16-Bit DACPORT |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| AD668SQ/883B | 制造商:Analog Devices 功能描述:DAC 1-CH R-2R/Current Steering 12-bit 24-Pin CDIP Tube 制造商:Rochester Electronics LLC 功能描述:IC - 12-BIT MULT. DAC IC - Bulk |
| AD669 | 制造商:AD 制造商全稱:Analog Devices 功能描述:Monolithic 16-Bit DACPORT |
| AD669/883B | 制造商:AD 制造商全稱:Analog Devices 功能描述:Monolithic 16-Bit DACPORT |
| AD669883B | 制造商:AD 制造商全稱:Analog Devices 功能描述:Monolithic 16-Bit DACPORT |
| AD669AN | 功能描述:IC DAC 16BIT MONO W/VREF 28-DIP RoHS:否 類別:集成電路 (IC) >> 數(shù)據(jù)采集 - 數(shù)模轉(zhuǎn)換器 系列:DACPORT® 產(chǎn)品培訓(xùn)模塊:Data Converter Fundamentals DAC Architectures 標(biāo)準(zhǔn)包裝:750 系列:- 設(shè)置時(shí)間:7µs 位數(shù):16 數(shù)據(jù)接口:并聯(lián) 轉(zhuǎn)換器數(shù)目:1 電壓電源:雙 ± 功率耗散（最大）:100mW 工作溫度:0°C ~ 70°C 安裝類型:表面貼裝 封裝/外殼:28-LCC（J 形引線） 供應(yīng)商設(shè)備封裝:28-PLCC（11.51x11.51） 包裝:帶卷 (TR) 輸出數(shù)目和類型:1 電壓，單極；1 電壓，雙極 采樣率（每秒）:143k |
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