ADI公司的AD7193是具有PGA的4路4.8kHz超低噪音24位Sigma-Delta ADC，RMS噪音为11 nV @ 4.7 Hz (gain = 128)，失调漂移为±5 nV/℃ ，增益漂移为±1 ppm/℃，工作电压3V-5.25V，主要应用在PLC/DCS模拟输入模块，数据采集和应力仪传感器。本文介绍了AD7193主要特性，功能方框图，基本的连接框图，流量计的典型应用电路图以及过程控制应用的全编程通用模拟前端（CN0209）简化电路图和EVAL-CN0209-SDPZ评估板电路图，材料清单和PCB布局图。

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应用：

PLC/DCS analog input modules

Data acquisition

Strain gage transducers

 图1。AD7193功能方框图

图2。AD7193基本的连接框图

图3。AD7193典型应用电路图（流量计）

过程控制应用的全编程通用模拟前端（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评估板包括：

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 主要应用：

Energy

Motor and Power Control

Process Control & Industrial Automation

Sensors and Sensor Interface

Temperature Controllers

图4。过程控制应用的全编程通用模拟前端简化电路图

图5。EVAL-CN0209-SDPZ评估板电路图（1）

图6。EVAL-CN0209-SDPZ评估板电路图（2）
EVAL-CN0209-SDPZ评估板材料清单（BOM）：


图7。EVAL-CN0209-SDPZ评估板PCB布局图
详情请见：
http://www.analog.com/static/imported-files/data_sheets/AD7193.pdf
和
http://www.analog.com/en/circuits-from-the-lab/CN0209/vc.html