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参数资料
| 型号： | LTC2256IUJ-14#PBF |
| 厂商： | LINEAR TECHNOLOGY CORP |
| 元件分类： | ADC |
| 英文描述： | 1-CH 14-BIT PROPRIETARY METHOD ADC, PARALLEL ACCESS, PQCC40 |
| 封装： | 6 X 6 MM, LEAD FREE, PLASTIC, QFN-40 |
| 文件页数： | 16/32页 |
| 文件大小： | 1546K |
| 代理商： | LTC2256IUJ-14#PBF |
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225814fa
LTC2258-14
LTC2257-14/LTC2256-14
Digital Output Randomizer
Interference from the A/D digital outputs is sometimes
unavoidable. Digital interference may be from capacitive or
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 exclu-
sive-OR logic operation between the LSB and all other
data output bits. To decode, the reverse operation is ap-
plied—an exclusive-OR operation is applied between the
LSB and all other bits. The LSB, OF and CLKOUT outputs
are not affected. The output randomizer 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
that is centered around midscale, the digital outputs toggle
between mostly 1s and mostly 0s. This simultaneous
switching of most of the bits will cause large currents in
the ground plane. By inverting every other bit, the alter-
nate bit polarity mode makes half of the bits transition
high while half of the bits transition low. To rst order,
this cancels current ow in the ground plane, reducing
the digital noise.
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
相关PDF资料 |
PDF描述 |
|---|---|
| LTC2257CUJ-14#PBF | 1-CH 14-BIT PROPRIETARY METHOD ADC, PARALLEL ACCESS, PQCC40 |
| LTC2257IUJ-14#PBF | 1-CH 14-BIT PROPRIETARY METHOD ADC, PARALLEL ACCESS, PQCC40 |
| LTC2259CUJ-16#PBF | PROPRIETARY METHOD ADC, PQCC40 |
| LTC2259IUJ-16#PBF | PROPRIETARY METHOD ADC, PQCC40 |
| LTC2259CUJ-16#TRPBF | PROPRIETARY METHOD ADC, PQCC40 |
相关代理商/技术参数 |
参数描述 |
|---|---|
| LTC2256IUJ-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 |
| LTC2256UJ-12 | 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 |
| LTC2256UJ-14 | 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 |
| LTC2257-12 | 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 |
| LTC2257-14 | 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 |
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