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: 9/32页
文件大小: 1546K
代理商: LTC2256IUJ-14#PBF
17
225814fa
LTC2258-14
LTC2257-14/LTC2256-14
CONVERTER OPERATION
The LTC2258-14/LTC2257-14/LTC2256-14 are low power
14-bit 65Msps/40Msps/25Msps A/D converters that are
powered by a single 1.8V supply. The analog inputs should
be driven differentially. The encode input can be driven
differentially, or single ended for lower power consump-
tion. The digital outputs can be CMOS, double data rate
CMOS (to halve the number of output lines), or double
data rate LVDS (to reduce digital noise in the system.)
Many additional features can be chosen by programming
the mode control registers through a serial SPI port. See
the Serial Programming Mode section.
ANALOG INPUT
The analog input is a differential CMOS sample-and-hold
circuit (Figure 2). The inputs should be driven differentially
around a common mode voltage set by the VCM output
pin, which is nominally VDD/2. For the 2V input range, the
inputs should swing from VCM – 0.5V to VCM + 0.5V. There
should be 180° phase difference between the inputs.
INPUT DRIVE CIRCUITS
Input ltering
If possible, there should be an RC lowpass lter right at
the analog inputs. This lowpass lter isolates the drive
circuitry from the A/D sample-and-hold switching, and
also limits wideband noise from the drive circuitry. Figure 3
shows an example of an input RC lter. The RC component
values should be chosen based on the application’s input
frequency.
Transformer Coupled Circuits
Figure 3 shows the analog input being driven by an RF
transformer with a center-tapped secondary. The center
tap is biased with VCM, setting the A/D input at its optimal
CSAMPLE
3.5pF
RON
25Ω
RON
25Ω
VDD
LTC2258-14
AIN
+
225814 F02
CSAMPLE
3.5pF
VDD
AIN
ENC
ENC+
1.2V
10k
1.2V
10k
CPARASITIC
1.8pF
CPARASITIC
1.8pF
10Ω
25Ω
50Ω
0.1μF
AIN
+
AIN
12pF
0.1μF
VCM
LTC2258-14
ANALOG
INPUT
0.1μF
T1
1:1
T1: MA/COM MABAES0060
RESISTORS, CAPACITORS
ARE 0402 PACKAGE SIZE
225814 F03
Figure 2. Equivalent Input Circuit
Figure 3. Analog Input Circuit Using a Transformer.
Recommended for Input Frequencies from 5MHz to 70MHz
APPLICATIONS INFORMATION
相关PDF资料
PDF描述
LTC2257CUJ-14#PBF 1-CH 14-BIT PROPRIETARY METHOD ADC, PARALLEL ACCESS, PQCC40
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LTC2259CUJ-16#PBF PROPRIETARY METHOD ADC, PQCC40
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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