参数资料
| 型号： | LTC1744IFW#TRPBF |
| 厂商： | Linear Technology |
| 文件页数： | 6/24页 |
| 文件大小： | 0K |
| 描述： | IC ADC 14BIT 50MSPS 48-TSSOP |
| 标准包装： | 1,800 |
| 位数： | 14 |
| 采样率（每秒）： | 50M |
| 数据接口： | 并联 |
| 转换器数目： | 1 |
| 功率耗散（最大）： | 1.5W |
| 电压电源： | 单电源 |
| 工作温度： | -40°C ~ 85°C |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 48-TFSOP（0.240"，6.10mm 宽） |
| 供应商设备封装： | 48-TSSOP |
| 包装： | 带卷 (TR) |
| 输入数目和类型： | 2 个单端，双极；1 个差分，双极 |
14
LTC1744
1744f
APPLICATIO S I FOR ATIO
WU
U
Input Drive Circuits
Figure 3 shows the LTC1744 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
signal at its optimum DC level. Figure 3 shows a 1:1 turns
ratio transformer. Other turns ratios can be used if the
source impedence seen by the ADC does not exceed 100
for each ADC input. A disadvantage of using a transformer
is the loss of low frequency response. Most small RF
transformers have poor performance at frequencies be-
low 1MHz.
frequencies higher than 40MHz, the capacitors may need
to be decreased to prevent excessive signal loss.
Reference Operation
Figure 5 shows the LTC1744 reference circuitry consisting
of a 2.5V bandgap reference, a difference amplifier and
switching and control circuit. The internal voltage refer-
ence can be configured for two pin selectable input ranges
of 2V(
±1V differential) or 3.2V(±1.6V differential). Tying
the SENSE pin to ground selects the 2V range; tying the
SENSE pin to VDD selects the 3.2V range.
The 2.5V bandgap reference serves two functions: its
output provides a DC bias point for setting the common
mode voltage of any external input circuitry; additionally,
the reference is used with a difference amplifier to gener-
ate the differential reference levels needed by the internal
ADC circuitry.
1:1
37
0.1
F
ANALOG
INPUT
VCM
AIN
+
AIN
–
100
100
18pF
1744 F03
4.7
F
37
LTC1744
37
5V
SINGLE-ENDED
INPUT
2.5V
±1/2 RANGE
VCM
AIN
+
AIN
–
18pF
1744 F04a
4.7
F
37
100
500
500
LTC1744
–
+
1/2 LT1810
–
+
1/2 LT1810
Figure 3. Single-Ended to Differential
Conversion Using a Transformer
Figure 4a. Differential Drive with Op Amps
Figure 4b. Using the LT6600 as a Differential Driver
5V
1
4
3
GAIN = 402
/RIN
MAXIMUM GAIN = 4
5
6
2
7
8
VCM
AIN
+
AIN
–
18pF
1744 F04b
1
F
49.9
49.9
RIN
402
RIN
402
0.1
F
0.01
F
LTC1744
–
+
–
+
LT6600-20
VOCM
VMID
VIN
Figure 4a demonstrates the use of operational amplifiers
to convert a single ended input signal into a differential
input signal. The advantage of this method is that it
provides low frequency input response; however, the
limited gain bandwidth of most op amps will limit the
SFDR at high input frequencies.
Figure 4b shows the LT6600, a low noise differential
amplifier and lowpass filter, used as an input driver. The
LT6600 provides two functions: it serves as a 4th order
lowpass filter and as a single-ended to differential con-
verter. Additionally it can be programmed with one exter-
nal resistor to provide a gain from 1 to 4. Three versions
of this device are available having lowpass filter band-
widths of 2.5MHz, 10MHz or 20MHz.
The 37
resistors and 18pF capacitors on the analog
inputs serve two purposes: isolating the drive circuitry
from the sample-and-hold charging glitches and limiting
the wideband noise at the converter input. For input
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相关代理商/技术参数 |
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| LTC1745CFW | 功能描述:IC ADC 12BIT 25MSPS LN 48TSSOP RoHS:否 类别:集成电路 (IC) >> 数据采集 - 模数转换器 系列:- 标准包装:1,000 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 |
| LTC1745CFW#PBF | 功能描述:IC ADC 12BIT 25MSPS LN 48TSSOP RoHS:是 类别:集成电路 (IC) >> 数据采集 - 模数转换器 系列:- 产品培训模块:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 标准包装:2,500 系列:- 位数:12 采样率（每秒）:3M 数据接口:- 转换器数目:- 功率耗散（最大）:- 电压电源:- 工作温度:- 安装类型:表面贴装 封装/外壳:SOT-23-6 供应商设备封装:SOT-23-6 包装:带卷 (TR) 输入数目和类型:- |
| LTC1745CFW#TR | 功能描述:IC ADC SMPL 12BIT 25MSPS 48TSSOP RoHS:否 类别:集成电路 (IC) >> 数据采集 - 模数转换器 系列:- 标准包装:1,000 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 |
| LTC1745CFW#TRPBF | 功能描述:IC ADC 12BIT 25MSPS LN 48TSSOP RoHS:是 类别:集成电路 (IC) >> 数据采集 - 模数转换器 系列:- 产品培训模块:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 标准包装:2,500 系列:- 位数:12 采样率（每秒）:3M 数据接口:- 转换器数目:- 功率耗散（最大）:- 电压电源:- 工作温度:- 安装类型:表面贴装 封装/外壳:SOT-23-6 供应商设备封装:SOT-23-6 包装:带卷 (TR) 输入数目和类型:- |
| LTC1745IFW | 功能描述:IC ADC SMPL 12BIT 25MSPS 48TSSOP RoHS:否 类别:集成电路 (IC) >> 数据采集 - 模数转换器 系列:- 标准包装:1,000 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 |
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