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| 型号： | ADS1241MEVM |
| 厂商： | Texas Instruments |
| 文件页数： | 4/30页 |
| 文件大小： | 0K |
| 描述： | EVALUATION MODULE FOR ADS1241M |
| 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 |
| ADC 的数量： | 1 |
| 位数： | 24 |
| 采样率（每秒）： | 15 |
| 数据接口： | SPI? |
| 输入范围： | 0 ~ 2.5 V |
| 在以下条件下的电源（标准）： | 0.6mW @ 3V |
| 工作温度： | -40°C ~ 85°C |
| 已用 IC / 零件： | ADS1241M |
| 已供物品： | 板 |
| 产品目录页面： | 889 (CN2011-ZH PDF) |
| 相关产品： | ADS1241EG4-ND - IC ADC 24-BIT SER PROGBL 28-SSOP ADS1241E/1KG4-ND - IC ADC 24-BIT SER PROGBL 28-SSOP 296-25895-2-ND - IC ADC 24-BIT SER PROGBL 28-SSOP ADS1241E-ND - IC ADC 24-BIT SER PROGBL 28-SSOP |
| 其它名称： | 296-18358 |
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ADS1240, 1241
12
SBAS173F
www.ti.com
SELFGCAL. Afterwards set PGA = 64 and issue SELFOCAL.
For operation with a reference voltage greater than (AVDD –
1.5) volts, the buffer must also be turned off during gain self-
calibration to avoid exceeding the buffer input range.
System calibration corrects both internal and external offset
and gain errors. While performing system calibration, the
appropriate signal must be applied to the inputs. The system
offset calibration command (SYSOCAL) requires a zero input
differential signal (see Table IV, page 18). It then computes
the offset that nullifies the offset in the system. The system
gain calibration command (SYSGCAL) requires a positive
full-scale input signal. It then computes a value to nullify the
gain error in the system. Each of these calibrations takes two
tDATA periods to complete. System gain calibration is recom-
mended for the best gain calibration at higher PGAs.
Calibration should be performed after power on, a change in
temperature, or a change of the PGA. The RANGE bit (ACR bit
2) must be zero during calibration.
Calibration removes the effects of the ODAC; therefore, dis-
able the ODAC during calibration, and enable again after
calibration is complete.
At the completion of calibration, the DRDY signal goes low,
indicating the calibration is finished. The first data after
calibration should be discarded since it may be corrupt from
calibration data remaining in the filter. The second data is
always valid.
EXTERNAL VOLTAGE REFERENCE
The ADS1240 and ADS1241 require an external voltage
reference. The selection for the voltage reference value is
made through the ACR register.
The external voltage reference is differential and is repre-
sented by the voltage difference between the pins: +VREF
and –VREF. The absolute voltage on either pin, +VREF or
–VREF, can range from AGND to AVDD. However, the follow-
ing limitations apply:
For AVDD = 5.0V and RANGE = 0 in the ACR, the differential
VREF must not exceed 2.5V.
For AVDD = 5.0V and RANGE = 1 in the ACR, the differential
VREF must not exceed 5V.
For AVDD = 3.0V and RANGE = 0 in the ACR, the differential
VREF must not exceed 1.25V.
For AVDD = 3.0V and RANGE = 1 in the ACR, the differential
VREF must not exceed 2.5V.
CLOCK GENERATOR
The clock source for the ADS1240 and ADS1241 can be
provided from a crystal, oscillator, or external clock. When the
clock source is a crystal, external capacitors must be provided
to ensure start-up and stable clock frequency. This is shown in
both Figure 5 and Table II. XOUT is only for use with external
crystals and it should not be used as a clock driver for external
circuitry.
FIGURE 5. Crystal Connection.
CLOCK
PART
SOURCE
FREQUENCY
C1
C2
NUMBER
Crystal
2.4576
0-20pF
ECS, ECSD 2.45 - 32
Crystal
4.9152
0-20pF
ECS, ECSL 4.91
Crystal
4.9152
0-20pF
ECS, ECSD 4.91
Crystal
4.9152
0-20pF
CTS, MP 042 4M9182
TABLE II. Recommended Crystals.
DIGITAL FILTER
The ADS1240 and ADS1241 have a 1279 tap linear phase
Finite Impulse Response (FIR) digital filter that a user can
configure for various output data rates. When a 2.4576MHz
crystal is used, the device can be programmed for an output
data rate of 15Hz, 7.5Hz, or 3.75Hz. Under these conditions,
the digital filter rejects both 50Hz and 60Hz interference. Figure
6 shows the digital filter frequency response for data output
rates of 15Hz, 7.5Hz, and 3.75Hz.
If a different data output rate is desired, a different crystal
frequency can be used. However, the rejection frequencies
shift accordingly. For example, a 3.6864MHz master clock with
the default register condition has:
(3.6864MHz/2.4576MHz) 15Hz = 22.5Hz data output rate
and the first and second notch is:
1.5 (50Hz and 60Hz) = 75Hz and 90Hz
DATA I/O INTERFACE
The ADS1240 has four pins and the ADS1241 has eight pins
that serve a dual purpose as both analog inputs and data
I/O. These pins are powered from AVDD and are configured
through the IOCON, DIR, and DIO registers. These pins
can be individually configured as either analog inputs or data
I/O. See Figure 7 (page 14) for the equivalent schematic of
an Analog/Data I/O pin.
The IOCON register defines the pin as either an analog input
or data I/O. The power-up state is an analog input. If the pin
is configured as an analog input in the IOCON register, the
DIR and DIO registers have no effect on the state of the pin.
If the pin is configured as data I/O in the IOCON register,
then DIR and DIO are used to control the state of the pin.
The DIR register controls the direction of the data pin, either
as an input or output. If the pin is configured as an input in
the DIR register, then the corresponding DIO register bit
reflects the state of the pin. Make sure the pin is driven to a
C
1
Crystal
X
IN
X
OUT
C
2
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相关代理商/技术参数 |
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| ADS1242 | 制造商:TI 制造商全称:Texas Instruments 功能描述:24-Bit ANALOG-TO-DIGITAL CONVERTER |
| ADS1242IPW | 制造商:Texas Instruments 功能描述:IC 24BIT ADC SMD 1242 TSSOP16 制造商:Texas Instruments 功能描述:IC, 24BIT ADC, SMD, 1242, TSSOP16 |
| ADS1242IPW | 制造商:Texas Instruments 功能描述:IC 24BIT ADC SMD 1242 TSSOP16 |
| ADS1242IPWR | 功能描述:模数转换器 - ADC 24-Bit ADC 4 Ch 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 |
| ADS1242IPWRG4 | 功能描述:模数转换器 - ADC 24-Bit ADC 4 Ch 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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