ADI公司的AD7193是具有PGA的4路4.8kHz超低噪音24位Sigma-Delta ADC，RMS噪音為11 nV @ 4.7 Hz (gain = 128)，失調(diào)漂移為±5 nV/℃ ，增益漂移為±1 ppm/℃，工作電壓3V-5.25V，主要應(yīng)用在PLC/DCS模擬輸入模塊，數(shù)據(jù)采集和應(yīng)力儀傳感器。本文介紹了AD7193主要特性，功能方框圖，基本的連接框圖，流量計(jì)的典型應(yīng)用電路圖以及過程控制應(yīng)用的全編程通用模擬前端（CN0209）簡化電路圖和EVAL-CN0209-SDPZ評估板電路圖，材料清單和PCB布局圖。
The AD7193 is a low noise, complete analog front end for high precision measurement applications. It contains a low noise, 24-bit sigma-delta (Σ-Δ) analog-to-digital converter (ADC). The on-chip low noise gain stage means that signals of small amplitude can interface directly to the ADC.
The device can be configured to have four differential inputs or eight pseudo differential inputs. The on-chip channel sequencer allows several channels to be enabled simultaneously, and the AD7193 sequentially converts on each enabled channel, simplifying communication with the part. The on-chip 4.92 MHz clock can be used as the clock source to the ADC or, alternatively, an external clock or crystal can be used. The output data rate from the part can be varied from 4.7 Hz to 4.8 kHz.
The device has a very flexible digital filter, including a fast settling option. Variables such as output data rate and settling time are dependent on the option selected. The AD7193 also includes a zero latency option.
The part operates with a power supply from 3 V to 5.25 V. It consumes a current of 4.65 mA, and it is available in a 28-lead TSSOP package and a 32-lead LFCSP package.
AD7193主要特性：
Fast settling filter option
4 differential/8 pseudo differential input channels
RMS noise: 11 nV @ 4.7 Hz (gain = 128)
15.5 noise-free bits @ 2.4 kHz (gain = 128)
Up to 22 noise-free bits (gain = 1)
Offset drift: ±5 nV/℃
Gain drift: ±1 ppm/℃
Specified drift over time
Automatic channel sequencer
Programmable gain (1 to 128)
Output data rate: 4.7 Hz to 4.8 kHz
Internal or external clock
Simultaneous 50 Hz/60 Hz rejection
4 general-purpose digital outputs
Power supply
AVDD: 3 V to 5.25 V
DVDD: 2.7 V to 5.25 V
Current: 4.65 mA
Temperature range: −40℃ to +105℃
28-lead TSSOP and 32-lead LFCSP packages
Interface
3-wire serial
SPI, QSPI™, MICROWIRE™, and DSP compatible
Schmitt trigger on SCLK
AD7193應(yīng)用：
PLC/DCS analog input modules
Data acquisition
Strain gage transducers
圖1。AD7193功能方框圖
圖2。AD7193基本的連接框圖
圖3。AD7193典型應(yīng)用電路圖（流量計(jì)）
過程控制應(yīng)用的全編程通用模擬前端（CN0209）EVAL-CN0209-SDPZ
This circuit uses the EVAL-CN0209-SDPZ circuit board and the EVAL-SDP-CB1Z System Demonstration Platform (SDP) evaluation board. The two boards have 120-pin mating connectors, allowing for the quick setup and evaluation of the circuit’s performance. The EVAL-CN0209-SDPZ board contains the circuit to be evaluated, as described in this note, and the SDP evaluation board is used with the CN0209 evaluation software to capture the data from the EVAL-CN0209-SDPZ circuit board.
Equipment Needed
PC with a USB port and Windows® XP or Windows Vista® (32-bit) or Windows® 7 (32-bit)
EVAL-CN0209-SDPZ Circuit Evaluation Board
EVAL-SDP-CB1Z SDP Evaluation Board
CN0209 Evaluation Software
Power supply: +15 V and –15 V
RTD temperature sensor
Thermocouple
EVAL-CN0209-SDPZ評估板包括：
The EVAL-CN0209-SDPZ evaluation kit includes self-installing software on CD. The software is compatible with Windows® XP, Windows Vista (32-bits) and Windows 7 (32-bits).
The circuit shown in Figure 1 provides a fully programmable universal analog front end (AFE) for process control applications. The following inputs are supported: 2-, 3-, and 4- wire RTD configurations, thermocouple inputs with cold junction compensation, unipolar and bipolar input voltages, and 4 mA-to-20 mA inputs.
Today, many analog input modules use wire links (jumpers) to configure the customer input requirements. This requires time, knowledge, and manual intervention to configure and reconfigure the input. This circuit provides a software controllable switch to configure the modes along with a constant current source to excite the RTD. The circuit is also reconfigurable to set common-mode voltages for the thermocouple configuration. A differential amplifier is used to condition the analog input voltage range to the Σ-Δ ADC. The circuit provides industry-leading performance and cost.Because of the voltage gain provided by the AD8676 and AD8275, the design is particularly suitable for small signal inputs, all types of RTDs, or thermocouples.
The AD7193 is a 24-bit Σ-Δ ADC that can be configured to have four differential inputs or eight pseudo differential inputs. The ADuM1400 and ADuM1401provide all the necessary signal isolation between the microcontroller and the ADC. The circuit also includes standard external protection and is compliant with the IEC 61000 specifications.
EVAL-CN0209-SDPZ 主要應(yīng)用：
Energy
Motor and Power Control
Process Control & Industrial Automation
Sensors and Sensor Interface
Temperature Controllers
圖4。過程控制應(yīng)用的全編程通用模擬前端簡化電路圖
圖5。EVAL-CN0209-SDPZ評估板電路圖（1）
圖6。EVAL-CN0209-SDPZ評估板電路圖（2）
EVAL-CN0209-SDPZ評估板材料清單（BOM）：
圖7。EVAL-CN0209-SDPZ評估板PCB布局圖
詳情請見：
http://www.analog.com/static/imported-files/data_sheets/AD7193.pdf
和
http://www.analog.com/en/circuits-from-the-lab/CN0209/vc.html
