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參數(shù)資料
| 型號： | LTC2284CUP#PBF |
| 廠商： | Linear Technology |
| 文件頁數(shù)： | 11/24頁 |
| 文件大小： | 0K |
| 描述： | IC ADC DUAL 14BIT 105MSPS 64-QFN |
| 標(biāo)準(zhǔn)包裝： | 40 |
| 位數(shù)： | 14 |
| 采樣率（每秒）： | 105M |
| 數(shù)據(jù)接口： | 并聯(lián) |
| 轉(zhuǎn)換器數(shù)目： | 2 |
| 功率耗散（最大）： | 630mW |
| 電壓電源： | 單電源 |
| 工作溫度： | 0°C ~ 70°C |
| 安裝類型： | 表面貼裝 |
| 封裝/外殼： | 64-WFQFN 裸露焊盤 |
| 供應(yīng)商設(shè)備封裝： | 64-QFN（9x9） |
| 包裝： | 管件 |
| 輸入數(shù)目和類型： | 2 個(gè)單端，雙極; 2 個(gè)差分, 雙極 |
LTC2284
19
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APPLICATIO S I FOR ATIO
WU
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Grounding and Bypassing
The LTC2284 requires a printed circuit board with a clean,
unbroken ground plane. A multilayer board with an inter-
nal ground plane is recommended. Layout for the printed
circuit board should ensure that digital and analog signal
lines are separated as much as possible. In particular, care
should be taken not to run any digital track alongside an
analog signal track or underneath the ADC.
High quality ceramic bypass capacitors should be used at
the VDD, OVDD, VCM, REFH, and REFL pins. Bypass capaci-
tors must be located as close to the pins as possible. Of
particular importance is the 0.1
F capacitor between
REFH and REFL. This capacitor should be placed as close
to the device as possible (1.5mm or less). A size 0402
ceramic capacitor is recommended. The large 2.2
F ca-
pacitor between REFH and REFL can be somewhat further
away. The traces connecting the pins and bypass capaci-
tors must be kept short and should be made as wide as
possible.
The LTC2284 differential inputs should run parallel and
close to each other. The input traces should be as short as
possible to minimize capacitance and to minimize noise
pickup.
Heat Transfer
Most of the heat generated by the LTC2284 is transferred
from the die through the bottom-side exposed pad and
package leads onto the printed circuit board. For good
electrical and thermal performance, the exposed pad
should be soldered to a large grounded pad on the PC
board. It is critical that all ground pins are connected to a
ground plane of sufficient area.
Clock Sources for Undersampling
Undersampling raises the bar on the clock source, and the
higher the input frequency, the greater the sensitivity to
clock jitter or phase noise. A clock source that degrades
SNR of a full-scale signal by 1dB at 70MHz will degrade
SNR by 3dB at 140MHz, and 4.5dB at 190MHz.
In cases where absolute clock frequency accuracy is
relatively unimportant and only a single ADC is required,
a 3V canned oscillator from vendors such as Saronix or
Vectron can be placed close to the ADC and simply
connected directly to the ADC. If there is any distance to
the ADC, some source termination to reduce ringing that
may occur even over a fraction of an inch is advisable. You
must not allow the clock to overshoot the supplies or
performance will suffer. Do not filter the clock signal with
a narrow band filter unless you have a sinusoidal clock
source, as the rise and fall time artifacts present in typical
digital clock signals will be translated into phase noise.
The lowest phase noise oscillators have single-ended
sinusoidal outputs, and for these devices the use of a filter
close to the ADC may be beneficial. This filter should be
close to the ADC to both reduce roundtrip reflection times,
as well as reduce the susceptibility of the traces between
the filter and the ADC. If you are sensitive to close-in phase
noise, the power supply for oscillators and any buffers
must be very stable, or propagation delay variation with
supply will translate into phase noise. Even though these
clock sources may be regarded as digital devices, do not
operate them on a digital supply. If your clock is also used
to drive digital devices such as an FPGA, you should locate
the oscillator, and any clock fan-out devices close to the
ADC, and give the routing to the ADC precedence. The
clock signals to the FPGA should have series termination
at the driver to prevent high frequency noise from the
FPGA disturbing the substrate of the clock fan-out device.
If you use an FPGA as a programmable divider, you must
re-time the signal using the original oscillator, and the re-
timing flip-flop as well as the oscillator should be close to
the ADC, and powered with a very quiet supply.
For cases where there are multiple ADCs, or where the
clock source originates some distance away, differential
clock distribution is advisable. This is advisable both from
the perspective of EMI, but also to avoid receiving noise
from digital sources both radiated, as well as propagated
in the waveguides that exist between the layers of multi-
layer PCBs. The differential pairs must be close together
and distanced from other signals. The differential pair
should be guarded on both sides with copper distanced at
least 3x the distance between the traces, and grounded
with vias no more than 1/4 inch apart.
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| LTC2284IUP | 制造商:Linear Technology 功能描述:ADC Dual Pipelined 105Msps 14-bit Parallel 64-Pin QFN EP |
| LTC2284IUP#PBF | 功能描述:IC ADC DUAL 14BIT 105MSPS 64-QFN RoHS:是 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:microPOWER™ 位數(shù):8 采樣率（每秒）:1M 數(shù)據(jù)接口:串行，SPI? 轉(zhuǎn)換器數(shù)目:1 功率耗散（最大）:- 電壓電源:模擬和數(shù)字 工作溫度:-40°C ~ 125°C 安裝類型:表面貼裝 封裝/外殼:24-VFQFN 裸露焊盤 供應(yīng)商設(shè)備封裝:24-VQFN 裸露焊盤（4x4） 包裝:Digi-Reel® 輸入數(shù)目和類型:8 個(gè)單端，單極 產(chǎn)品目錄頁面:892 (CN2011-ZH PDF) 其它名稱:296-25851-6 |
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| LTC2284UP | 制造商:LINER 制造商全稱:Linear Technology 功能描述:Dual 14-Bit, 105Msps Low Power 3V ADC |
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