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| 型号： | ADS1222IPWT |
| 厂商： | Texas Instruments |
| 文件页数： | 5/26页 |
| 文件大小： | 0K |
| 描述： | IC 24BIT ADC W/2CH MUX 14-TSSOP |
| 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）： | 240 |
| 数据接口： | 串行 |
| 转换器数目： | 1 |
| 功率耗散（最大）： | 2.25mW |
| 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： | 14-TSSOP（0.173"，4.40mm 宽） |
| 供应商设备封装： | 14-TSSOP |
| 包装： | 标准包装 |
| 输入数目和类型： | 4 个单端，单极；2 个差分，双极 |
| 其它名称： | 296-17321-6 |
ADS1222
SBAS314B APRIL 2004 REVISED JANUARY 2009
www.ti.com
13
The ADS1222 uses a Sinc3 digital filter to improve noise
performance. Therefore, in certain instances, large
changes in input will require settling time. For example,
an external multiplexer in front of the ADS1222 can put
large changes in input voltage by simply switching input
channels. Abrupt changes in the input will require three
data cycles to settle. When continuously converting,
four readings may be necessary to settle the data. If the
change in input occurs in the middle of the first conver-
sion, three more full conversions of the fully settled input
will be required to get fully settled data. Discard the first
three readings because they will contain only partially-
settled data. Figure 24 illustrates the settling time for
the ADS1222 in Continuous Conversion mode.
If the input is known to change abruptly, the mux can be
quickly switched to an alternate channel and quickly
switched back to the original channel. By toggling the
mux, the ADS1222 resets the digital filter and initiates a
new conversion. During this time, the DRDY/DOUT line
is held high until fully-settled data is available.
DATA FORMAT
The ADS1222 outputs 24 bits of data in binary two’s
complement format. The least significant bit (LSB) has
a weight of (2VREF)/(223 – 1). The positive full-scale
input produces an output code of 7FFFFFh and the
negative full-scale input produces an output code of
800000h. The output clips at these codes for signals
exceeding full-scale. Table 2 summarizes the ideal
output codes for different input signals.
Table 2. Ideal Output Code vs Input Signal
INPUT SIGNAL VIN
(AINP AINN)
IDEAL OUTPUT CODE(1)
w +2V
REF
7FFFFFh
+2V
REF
223
* 1
000001h
0
000000h
2V
REF
223
* 1
FFFFFFh
v 2V
REF
223
* 1
800000h
(1) Excludes effects of noise, INL, offset, and gain errors.
DATA RETRIEVAL
The ADS1222 continuously converts the analog input
signal. To retrieve data, wait until DRDY/DOUT goes
low, as shown in Figure 25. After this occurs, begin
shifting out the data by applying SCLKs. Data is shifted
out MSB first. It is not required to shift out all 24 bits of
data, but the data must be retrieved before the new data
is updated (see t2) or else it will be overwritten. Avoid
data retrieval during the update period. DRDY/DOUT
remain at the state of the last bit shifted out until it is
taken high (see t6), indicating that new data is being
updated. To avoid having DRDY/DOUT remain in the
state of the last bit, shift a 25th SCLK to force
DRDY/DOUT high (see Figure 26). This technique is
useful when a host controlling the ADS1222 is polling
DRDY/DOUT to determine when data is ready.
Abrupt change in external V
IN
V
IN
DRDY/DOUT
Start of
conversion
First Conversion;
includes
unsettled V
IN
Second Conversion;
V
IN settled, but
digital filter
unsettled
Third Conversion;
V
IN settled, but
digital filter
unsettled
Fourth Conversion;
V
IN and digital filter
both settled
Conversion
time
Figure 24. Settling Time in Continuous Conversion Mode
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相关代理商/技术参数 |
参数描述 |
|---|---|
| ADS1222IPWT | 制造商:Texas Instruments 功能描述:IC 24-BIT ADC 2 CH DIFF I/P MULTI |
| ADS1222IPWTG4 | 功能描述:模数转换器 - ADC 24-Bit Conv w/2-Ch Diff Input Mltplxer 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 |
| ADS1224 | 制造商:BB 制造商全称:BB 功能描述:24-Bit Analog-to-Digital Converter with 4-Channel Differential Input Multiplexer |
| ADS1224EVM | 功能描述:数据转换 IC 开发工具 ADS1224 Eval Mod RoHS:否 制造商:Texas Instruments 产品:Demonstration Kits 类型:ADC 工具用于评估:ADS130E08 接口类型:SPI 工作电源电压:- 6 V to + 6 V |
| ADS1224IPWR | 功能描述:模数转换器 - ADC 24-bit 240SPS 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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