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参数资料
| 型号： | LTC2222CUK-11#PBF |
| 厂商： | Linear Technology |
| 文件页数： | 6/24页 |
| 文件大小： | 0K |
| 描述： | IC ADC 11BIT 105MSPS SAMPL 48QFN |
| 标准包装： | 52 |
| 位数： | 11 |
| 采样率（每秒）： | 105M |
| 数据接口： | 并联 |
| 转换器数目： | 1 |
| 功率耗散（最大）： | 535mW |
| 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： | 48-WFQFN 裸露焊盘 |
| 供应商设备封装： | 48-QFN-EP（7x7） |
| 包装： | 管件 |
| 输入数目和类型： | 1 个单端，双极; 1 个差分，双极 |
LTC2222-11
14
222211f
During the sample phase when ENC is low, the transistors
connect the analog inputs to the sampling capacitors and
they charge to, and track the differential input voltage.
When ENC transitions from low to high, the sampled input
voltage is held on the sampling capacitors. During the hold
phase when ENC is high, the sampling capacitors are
disconnected from the input and the held voltage is passed
to the ADC core for processing. As ENC transitions from
high to low, the inputs are reconnected to the sampling
capacitors to acquire a new sample. Since the sampling
capacitors still hold the previous sample, a charging glitch
proportional to the change in voltage between samples will
be seen at this time. If the change between the last sample
and the new sample is small, the charging glitch seen at
the input will be small. If the input change is large, such as
the change seen with input frequencies near Nyquist, then
a larger charging glitch will be seen.
Single-Ended Input
For cost sensitive applications, the analog inputs can be
driven single-ended. With a single-ended input the har-
monic distortion and INL will degrade, but the SNR and
DNL will remain unchanged. For a single-ended input, AIN+
should be driven with the input signal and AIN– should be
connected to 1.6V or VCM.
Common Mode Bias
For optimal performance the analog inputs should be
driven differentially. Each input should swing
±0.5V for
the 2V range or
±0.25V for the 1V range, around a
common mode voltage of 1.6V. The VCM output pin (Pin
44) may be used to provide the common mode bias level.
VCM can be tied directly to the center tap of a transformer
to set the DC input level or as a reference level to an op amp
differential driver circuit. The VCM pin must be bypassed to
ground close to the ADC with a 2.2
F or greater capacitor.
Input Drive Impedance
As with all high performance, high speed ADCs, the
dynamic performance of the LTC2222-11 can be influ-
enced by the input drive circuitry, particularly the second
and third harmonics. Source impedance and input reac-
tance can influence SFDR. At the falling edge of ENC, the
sample-and-hold circuit will connect the 1.6pF sampling
capacitor to the input pin and start the sampling period.
The sampling period ends when ENC rises, holding the
sampled input on the sampling capacitor. Ideally the input
circuitry should be fast enough to fully charge
the sampling capacitor during the sampling period
1/(2FENCODE); however, this is not always possible and the
incomplete settling may degrade the SFDR. The sampling
glitch has been designed to be as linear as possible to
minimize the effects of incomplete settling.
For the best performance, it is recommended to have a
source impedance of 100
or less for each input. The
source impedance should be matched for the differential
inputs. Poor matching will result in higher even order
harmonics, especially the second.
Input Drive Circuits
Figure 3 shows the LTC2222-11 being driven by an RF
transformer with a center tapped secondary. The second-
ary center tap is DC biased with VCM, setting the ADC input
25
25
25
25
0.1
F
AIN
+
AIN
–
12pF
2.2
F
VCM
LTC2222-11
ANALOG
INPUT
0.1
FT1
1:1
T1 = MA/COM ETC1-1T
RESISTORS, CAPACITORS
ARE 0402 PACKAGE SIZE
222211 F03
Figure 3. Single-Ended to Differential Conversion
Using a Transformer
APPLICATIO S I FOR ATIO
WU
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| LTC2222IUK | 功能描述:IC ADC 12BIT 105MSPS SAMPL 48QFN RoHS:否 类别:集成电路 (IC) >> 数据采集 - 模数转换器 系列:- 标准包装:1 系列:- 位数:14 采样率（每秒）:83k 数据接口:串行，并联 转换器数目:1 功率耗散（最大）:95mW 电压电源:双 ± 工作温度:0°C ~ 70°C 安装类型:通孔 封装/外壳:28-DIP（0.600"，15.24mm） 供应商设备封装:28-PDIP 包装:管件 输入数目和类型:1 个单端，双极 |
| LTC2222IUK#PBF | 功能描述:IC ADC 12BIT 105MSPS SAMPL 48QFN 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 系列:- 位数:14 采样率（每秒）:83k 数据接口:串行，并联 转换器数目:1 功率耗散（最大）:95mW 电压电源:双 ± 工作温度:0°C ~ 70°C 安装类型:通孔 封装/外壳:28-DIP（0.600"，15.24mm） 供应商设备封装:28-PDIP 包装:管件 输入数目和类型:1 个单端，双极 |
| LTC2222IUK#TR | 功能描述:IC ADC 12BIT 105MSPS SAMPL 48QFN RoHS:否 类别:集成电路 (IC) >> 数据采集 - 模数转换器 系列:- 标准包装:1 系列:- 位数:14 采样率（每秒）:83k 数据接口:串行，并联 转换器数目:1 功率耗散（最大）:95mW 电压电源:双 ± 工作温度:0°C ~ 70°C 安装类型:通孔 封装/外壳:28-DIP（0.600"，15.24mm） 供应商设备封装:28-PDIP 包装:管件 输入数目和类型:1 个单端，双极 |
| LTC2222IUK#TRPBF | 功能描述:IC ADC 12BIT 105MSPS SAMPL 48QFN 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 系列:- 位数:14 采样率（每秒）:83k 数据接口:串行，并联 转换器数目:1 功率耗散（最大）:95mW 电压电源:双 ± 工作温度:0°C ~ 70°C 安装类型:通孔 封装/外壳:28-DIP（0.600"，15.24mm） 供应商设备封装:28-PDIP 包装:管件 输入数目和类型:1 个单端，双极 |
| LTC2222IUK-11 | 制造商:LINER 制造商全称:Linear Technology 功能描述:11-Bit, 105Msps ADC |
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