參數(shù)資料
型號(hào)： AD9981KSTZ-95
廠商： ANALOG DEVICES INC
元件分類： 其它接口
英文描述： High Performance 10-Bit Display Interface
中文描述： SPECIALTY INTERFACE CIRCUIT, PQFP80
封裝： LEAD FREE, MS-026BEC, LQFP-80
文件頁(yè)數(shù)： 42/44頁(yè)
文件大?。?/td> 506K
代理商： AD9981KSTZ-95
AD9981
PCB LAYOUT RECOMMENDATIONS
The AD9981 is a high-precision, high-speed analog device.
To achieve the maximum performance from the part, it is
important to have a well laid-out board. The Analog Interface
Inputs section provides a guide for designing a board using
the AD9981.
Analog Interface Inputs
Using the following layout techniques on the graphics inputs is
extremely important:
Rev. 0 | Page 42 of 44
1.
Minimize the trace length running into the graphics inputs.
This is accomplished by placing the AD9981 as close as
possible to the graphics VGA connector. Long input trace
lengths are undesirable because they pick up noise from
the board and other external sources.
2.
Place the 75 termination resistors (see Figure 3) as close
as possible to the AD9981 chip. Any additional trace length
between the termination resistors and the input of the
AD9981 increases the magnitude of reflections, which
corrupts the graphics signal.
3.
Use 75 matched impedance traces. Trace impedances
other than 75 also increases the chance of reflections.
4.
The AD9981 has a very high input bandwidth, (200 MHz).
While this is desirable for acquiring a high resolution PC
graphics signal with fast edges, it also means that it
captures any high frequency noise present. Therefore, it is
important to reduce the amount of noise that gets coupled
to the inputs. Avoid running any digital traces near the
analog inputs.
5.
Due to the high bandwidth of the AD9981, sometimes
low-pass filtering the analog inputs can help to reduce
noise. (For many applications, filtering is unnecessary.)
Experiments have shown that placing a ferrite bead in
series prior to the 75 termination resistor is helpful in
filtering excess noise. Specifically, the Fair-Rite
#2508051217Z0 was used, but an application could work
best with a different bead value. Alternatively, placing a
100 to 120 resistor between the 75 termination
resistor and the input coupling capacitor is beneficial.
Power Supply Bypassing
It is recommended to bypass each power supply pin with a
0.1 μF capacitor. The exception is where two or more supply
pins are adjacent to each other. For these groupings of
powers/grounds, it is only necessary to have one bypass
capacitor. The fundamental idea is to have a bypass capacitor
within about 0.5 cm of each power pin. Also, avoid placing the
capacitor on the opposite side of the PC board from the
AD9981, since that interposes resistive vias in the path.
The bypass capacitors should be physically located between the
power plane and the power pin. Current should flow from the
power plane to the capacitor to the power pin. Do not make the
power connection between the capacitor and the power pin.
Placing a via underneath the capacitor pads, down to the power
plane, is generally the best approach.
It is particularly important to maintain low noise and good
stability of the PV
D
(the clock generator supply). Abrupt
changes in PV
D
can result in similarly abrupt changes in
sampling clock phase and frequency. This can be avoided by
careful attention to regulation, filtering, and bypassing. It is
highly desirable to provide separate regulated supplies for each
of the analog circuitry groups (V
D
and PV
D
).
Some graphic controllers use substantially different levels of
power when active (during active picture time) and when idle
(during horizontal and vertical sync periods). This can result in
a measurable change in the voltage supplied to the analog
supply regulator, which can in turn produce changes in the
regulated analog supply voltage. This can be mitigated by
regulating the analog supply, or at least PV
D
, from a different,
cleaner, power source (for example, from a 12 V supply).
It is also recommended to use a single ground plane for the
entire board. Experience has repeatedly shown that the noise
performance is the same or better with a single ground plane.
Using multiple ground planes can be detrimental because each
separate ground plane is smaller and long ground loops can
result.
In some cases, using separate ground planes is unavoidable. For
those cases, it is recommended to at least place a single ground
plane under the AD9981. The location of the split should be at
the receiver of the digital outputs. In this case it is even more
important to place components wisely because the current
loops will be much longer (current takes the path of least
resistance). An example of a current loop is power plane to
AD9981 to digital output trace to digital data receiver to digital
ground plane to analog ground plane.
PLL
Place the PLL loop filter components as close to the FILT pin as
possible. Do not place any digital or other high frequency traces
near these components. Use the values suggested in the data
sheet with 10% tolerances or less.
Outputs (Both Data and Clocks)
Try to minimize the trace length that the digital outputs have to
drive. Longer traces have higher capacitance and require more
instantaneous current to drive, which creates more internal
digital noise. Shorter traces reduce the possibility of reflections.
相關(guān)PDF資料
PDF描述
AD9983AKSTZ-140 High Performance 8-Bit Display Interface
AD9983AKSTZ-1401 High Performance 8-Bit Display Interface
AD9983AKSTZ-170 High Performance 8-Bit Display Interface
AD9983AKSTZ-1701 High Performance 8-Bit Display Interface
AD9983A High Performance 8-Bit Display Interface
相關(guān)代理商/技術(shù)參數(shù)
參數(shù)描述
AD9981XSTZ-110 制造商:Analog Devices 功能描述:HIGH PERFORMANCE 10-BIT DISPLAY INTERFACE - Bulk
AD9983A 制造商:AD 制造商全稱:Analog Devices 功能描述:High Performance 8-Bit Display Interface
AD9983A/PCB 制造商:AD 制造商全稱:Analog Devices 功能描述:High Performance 8-Bit Display Interface
AD9983A/PCBZ 功能描述:KIT EVALUATION AD9983A RoHS:是 類別:編程器，開(kāi)發(fā)系統(tǒng) >> 評(píng)估演示板和套件 系列:Advantiv® 標(biāo)準(zhǔn)包裝:1 系列:PCI Express® (PCIe) 主要目的:接口，收發(fā)器，PCI Express 嵌入式:- 已用 IC / 零件:DS80PCI800 主要屬性:- 次要屬性:- 已供物品:板
AD9983AKCPZ-140 功能描述:IC INTRFACE 8BIT 140MSPS 64LFCSP RoHS:是 類別:集成電路 (IC) >> 接口 - 專用 系列:- 特色產(chǎn)品:NXP - I2C Interface 標(biāo)準(zhǔn)包裝:1 系列:- 應(yīng)用:2 通道 I²C 多路復(fù)用器 接口:I²C，SM 總線 電源電壓:2.3 V ~ 5.5 V 封裝/外殼:16-TSSOP（0.173"，4.40mm 寬） 供應(yīng)商設(shè)備封裝:16-TSSOP 包裝:剪切帶 (CT) 安裝類型:表面貼裝 產(chǎn)品目錄頁(yè)面:825 (CN2011-ZH PDF) 其它名稱:568-1854-1
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