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| 型号： | ADS1244IDGST |
| 厂商： | Texas Instruments |
| 文件页数： | 22/24页 |
| 文件大小： | 0K |
| 描述： | IC ADC LP 24-BIT 10-MSOP |
| 产品培训模块： | Data Converter Basics |
| 视频文件： | Nuts and Bolts of the Delta-Sigma Converter |
| 标准包装： | 1 |
| 位数： | 24 |
| 采样率（每秒）： | 15 |
| 数据接口： | 串行 |
| 转换器数目： | 1 |
| 功率耗散（最大）： | 270µW |
| 电压电源： | 模拟和数字 |
| 工作温度： | -40°C ~ 85°C |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 10-TFSOP，10-MSOP（0.118"，3.00mm 宽） |
| 供应商设备封装： | 10-MSOP |
| 包装： | 标准包装 |
| 输入数目和类型： | 2 个单端，单极；1 个差分，双极 |
| 产品目录页面： | 889 (CN2011-ZH PDF) |
| 配用： | 296-18359-ND - EVALUATION MODULE FOR ADS1244 |
| 其它名称： | 296-14003-6 |
ADS1244
7
SBAS273
www.ti.com
OVERVIEW
The ADS1244 is an A/D converter comprised of a 3rd-order
modulator followed by a digital filter. The modulator measures
the differential input signal VIN = (AINP – AINN) against the
differential reference VREF = (VREFP – VREFN). Figure 1
shows a conceptual diagram. The differential reference is
scaled internally so that the full-scale input range is
±2V
REF.
The digital filter receives the modulator’s signal and provides
a low-noise digital output. The filter also sets the frequency
response of the converter and provides 50Hz and 60Hz
rejection while settling in a single conversion cycle. A 2-wire
serial interface indicates conversion completion and provides
the user with the output data.
The constant charging of the input capacitors presents a load
on the inputs that can be represented by effective imped-
ances. Figure 4 shows the input circuitry with the capacitors
and switches of Figure 2 replaced by their effective imped-
ances. These impedances scale inversely with fCLK fre-
quency. For example, if fCLK’s frequency is reduced by a
factor of 2, the impedances will double.
FIGURE 1. Conceptual Diagram of the ADS1244.
Modulator
Digital
Filter and
Serial
Interface
Σ
2
VREFP VREFN
V
REF
Σ
AINN
AINP
DRDY/DOUT
SCLK
CLK
V
IN
2V
REF
ANALOG INPUTS (AINP, AINN)
The input signal to be measured is applied to the input pins
AINP and AINN. The ADS1244 accepts differential input
signals, but can also measure unipolar signals. When mea-
suring unipolar (or “single-ended” signals) with respect to
ground, connect the negative input (AINN) to ground and
connect the input signal to the positive input (AINP). Note
that when the ADS1244 is used this way, only half of the
converter’s full-scale range is used since only positive digital
output codes will be produced.
The ADS1244 measures the input signal using internal
capacitors that are continuously charged and discharged.
Figure 2 shows a simplified schematic of the ADS1244’s
input circuitry with Figure 3 showing the ON/OFF timings of
the switches. S1 switches close during the input sampling
phase. With S1 closed, CA1 charges to AINP, CA2 charges to
AINN, and CB charges to (AINP – AINN). For the discharge
phase, S1 opens first and then S2 closes. CA1 and CA2
discharge to approximately AVDD/2 and CB discharges to
0V. This 2-phase sample/discharge cycle repeats with a
frequency of fCLK/128 (19.2kHz for fCLK = 2.4576MHz).
FIGURE 2. Simplified Input Structure.
S
1
AVDD
ESD Protection
AINP
AVDD/2
C
A1 = 4pF
C
B = 8pF
C
A2 = 4pF
S
2
S
1
AVDD
AINN
AVDD/2
S
2
FIGURE 3. S1 and S2 Switch Timing for Figure 1.
ON
OFF
ON
S
1
S
2
OFF
t
SAMPLE = 128/fCLK
FIGURE 4. Effective Analog Input Impedances.
Zeff
A = tSAMPLE/CA1 = 13M
(1)
Zeff
B = tSAMPLE/CB = 6.5M
(1)
Zeff
A = tSAMPLE/CA2 = 13M
(1)
NOTE: (1) f
CLK = 2.4576MHz.
AINP
AINN
AVDD/2
ESD diodes protect the inputs. To keep these diodes from turning
on, make sure the voltages on the input pins do not go below
GND by more than 100mV, and likewise do not exceed AVDD by
100mV: GND – 100mV < (AINP, AINN) < AVDD + 100mV.
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相关代理商/技术参数 |
参数描述 |
|---|---|
| ADS1244IDGSTG4 | 功能描述:模数转换器 - ADC 24-Bit Delta-Sigma 15SPS w/50-60Hz rej RoHS:否 制造商:Texas Instruments 通道数量:2 结构:Sigma-Delta 转换速率:125 SPs to 8 KSPs 分辨率:24 bit 输入类型:Differential 信噪比:107 dB 接口类型:SPI 工作电源电压:1.7 V to 3.6 V, 2.7 V to 5.25 V 最大工作温度:+ 85 C 安装风格:SMD/SMT 封装 / 箱体:VQFN-32 |
| ADS1245 | 制造商:BB 制造商全称:BB 功能描述:Low-Power, 24-Bit Analog-to-Digital Converter |
| ADS1245IDGSR | 功能描述:模数转换器 - ADC 24-bit Low-Power w/Hi-Z Input Buffer RoHS:否 制造商:Texas Instruments 通道数量:2 结构:Sigma-Delta 转换速率:125 SPs to 8 KSPs 分辨率:24 bit 输入类型:Differential 信噪比:107 dB 接口类型:SPI 工作电源电压:1.7 V to 3.6 V, 2.7 V to 5.25 V 最大工作温度:+ 85 C 安装风格:SMD/SMT 封装 / 箱体:VQFN-32 |
| ADS1245IDGSRG4 | 功能描述:模数转换器 - ADC 24-bit Low-Power w/Hi-Z Input Buffer RoHS:否 制造商:Texas Instruments 通道数量:2 结构:Sigma-Delta 转换速率:125 SPs to 8 KSPs 分辨率:24 bit 输入类型:Differential 信噪比:107 dB 接口类型:SPI 工作电源电压:1.7 V to 3.6 V, 2.7 V to 5.25 V 最大工作温度:+ 85 C 安装风格:SMD/SMT 封装 / 箱体:VQFN-32 |
| ADS1245IDGST | 功能描述:模数转换器 - ADC 24-bit Low-Power w/Hi-Z Input Buffer RoHS:否 制造商:Texas Instruments 通道数量:2 结构:Sigma-Delta 转换速率:125 SPs to 8 KSPs 分辨率:24 bit 输入类型:Differential 信噪比:107 dB 接口类型:SPI 工作电源电压:1.7 V to 3.6 V, 2.7 V to 5.25 V 最大工作温度:+ 85 C 安装风格:SMD/SMT 封装 / 箱体:VQFN-32 |
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