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参数资料
| 型号： | LTC2257CUJ-14#PBF |
| 厂商： | Linear Technology |
| 文件页数： | 17/34页 |
| 文件大小： | 0K |
| 描述： | IC ADC 14BIT 40MSPS 1.8V 40-QFN |
| 产品培训模块： | LTC2262 - Ultra Low Power High Speed ADCs |
| 标准包装： | 61 |
| 位数： | 14 |
| 采样率（每秒）： | 40M |
| 数据接口： | 并联，串行，SPI |
| 转换器数目： | 1 |
| 功率耗散（最大）： | 54mW |
| 电压电源： | 单电源 |
| 工作温度： | 0°C ~ 70°C |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 40-WFQFN 裸露焊盘 |
| 供应商设备封装： | 40-QFN（6x6） |
| 包装： | 管件 |
| 输入数目和类型： | 1 个差分 |
| 配用： | DC718C-ND - DEMO QUIKEVAL-II DATA |
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LTC2258-14
LTC2257-14/LTC2256-14
24
225814fc
For more information www.linear.com/LTC2258-14
Digital Output Randomizer
Interference from the A/D digital outputs is sometimes
unavoidable.Digitalinterferencemaybefromcapacitiveor
inductive coupling or coupling through the ground plane.
Even a tiny coupling factor can cause unwanted tones
in the ADC output spectrum. By randomizing the digital
output before it is transmitted off chip, these unwanted
tones can be randomized which reduces the unwanted
tone amplitude.
The digital output is “randomized” by applying an
exclusive-OR logic operation between the LSB and all
other data output bits. To decode, the reverse opera-
tion is applied—an exclusive-OR operation is applied
between the LSB and all other bits. The LSB, OF and
CLKOUT outputs are not affected. The output random-
izer is enabled by serially programming mode control
register A4.
Alternate Bit Polarity
Another feature that reduces digital feedback on the circuit
board is the alternate bit polarity mode. When this mode
is enabled, all of the odd bits (D1, D3, D5, D7, D9, D11,
D13) are inverted before the output buffers. The even bits
(D0, D2, D4, D6, D8, D10, D12), OF and CLKOUT are not
affected. This can reduce digital currents in the circuit
board ground plane and reduce digital noise, particularly
for very small analog input signals.
When there is a very small signal at the input of the A/D
thatiscenteredaroundmid-scale,thedigitaloutputstoggle
between mostly 1s and mostly 0s. This simultaneous
switchingofmostofthebitswillcauselargecurrentsinthe
ground plane. By inverting every other bit, the alternate bit
polarity mode makes half of the bits transition high while
half of the bits transition low. To first order, this cancels
currentflowinthegroundplane,reducingthedigitalnoise.
applicaTions inForMaTion
CLKOUT
OF
D13/D0
D12/D0
D2/D0
D1/D0
D0
225814 F15
OF
D13
D12
D2
D1
D0
RANDOMIZER
ON
D13
FPGA
PC BOARD
D12
D2
D1
D0
225814 F16
D0
D1/D0
D2/D0
D12/D0
D13/D0
OF
CLKOUT
LTC2258-14
Figure 15. Functional Equivalent of Digital Output Randomizer
Figure 16. Unrandomizing a Randomized Digital
Output Signal
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相关代理商/技术参数 |
参数描述 |
|---|---|
| LTC2257CUJ-14-TRPBF | 制造商:LINER 制造商全称:Linear Technology 功能描述:14-Bit, 65/40/25Msps Ultralow Power 1.8V ADCs |
| LTC2257IUJ-12#PBF | 功能描述:IC ADC 12BIT 40MSPS 1.8V 40-QFN RoHS:是 类别:集成电路 (IC) >> 数据采集 - 模数转换器 系列:- 标准包装:1,000 系列:- 位数:12 采样率（每秒）:300k 数据接口:并联 转换器数目:1 功率耗散（最大）:75mW 电压电源:单电源 工作温度:0°C ~ 70°C 安装类型:表面贴装 封装/外壳:24-SOIC（0.295"，7.50mm 宽） 供应商设备封装:24-SOIC 包装:带卷 (TR) 输入数目和类型:1 个单端，单极；1 个单端，双极 |
| LTC2257IUJ-12#TRPBF | 功能描述:IC ADC 12BIT 40MSPS 1.8V 40-QFN RoHS:是 类别:集成电路 (IC) >> 数据采集 - 模数转换器 系列:- 标准包装:1,000 系列:- 位数:12 采样率（每秒）:300k 数据接口:并联 转换器数目:1 功率耗散（最大）:75mW 电压电源:单电源 工作温度:0°C ~ 70°C 安装类型:表面贴装 封装/外壳:24-SOIC（0.295"，7.50mm 宽） 供应商设备封装:24-SOIC 包装:带卷 (TR) 输入数目和类型:1 个单端，单极；1 个单端，双极 |
| LTC2257IUJ-12-PBF | 制造商:LINER 制造商全称:Linear Technology 功能描述:12-Bit, 65/40/2 5Msps Ultralow Power 1.8V ADCs |
| LTC2257IUJ-12-TRPBF | 制造商:LINER 制造商全称:Linear Technology 功能描述:12-Bit, 65/40/2 5Msps Ultralow Power 1.8V ADCs |
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