原标题：TI LMP91050非分散红外(NDIR)检测AFE解决方案

　　TI 公司的LMP91050是可编程的传感器模拟前端(AFE)，最适合用于温度传感器和非分散红外(NDIR)检测应用。器件提供了传感器和MCU间完整的通路，可编程增益从167V/V到7986V/V，工作电压2.7V 到5.5V，(0.1 到10 Hz)噪音为 0.1μVRMS，最大增益漂移为100 ppm/℃，相位漂移为500ns，主要用在NDIR检测，通风控制，建筑物监测，汽车电子的CO2舱控制和酒精检测，GHG和氟利昂检测平台。本文介绍了LMP91050主要指标和特性，方框图，典型NDIR传感应用电路图以及SPIO-4精密信号通路控制器板主要特性，方框图，电路图和PCB元件布局图。

　　Configurable AFE for Nondispersive Infrared (NDIR) Sensing Applications

　　The LMP91050 is a programmable integrated Sensor Analog Front End (AFE) optimized for thermopile sensors, as typically used in NDIR applications. It provides a complete signal path solution between a sensor and microcontroller that generates an output voltage proportional to the thermopile voltage. The LMP91050 s programmability enables it to support multiple thermopile sensors with a single design as opposed to the multiple discrete solutions.

　　The LMP91050 features a programmable gain amplifier (PGA), "dark phase" offset cancellation, and an adjustable common mode generator (1.15V or 2.59V) which increases output dynamic range. The PGA offers a low gain range of 167V/V to 1335V/V plus a high gain range of 1002V/V to 7986V/V which enables the user to utilize thermopiles with different sensitivities.

　　LMP91050主要指标：

　　■ Programmable gain 167V/V to 7986V/V

　　■ Low noise (0.1 to 10 Hz) 0.1μVRMS

　　■ Gain Drift 100 ppm/°C (max)

　　■ Phase Delay Drift 500ns (max)

　　■ Power supply voltage range 2.7V to 5.5V

　　LMP91050主要特性：

　　Programmable gain amplifier

　　"Dark Signal" offset cancellation

　　Supports external filtering

　　Common mode generator and 8 bit DAC

　　10 pin MSOP package

　　LMP91050应用：

　　NDIR sensing

　　Demand control ventilation

　　Building monitoring

　　CO2 cabin control — Automotive

　　Alcohol detection — Automotive

　　Industrial safety and security

　　GHG & Freons detection platforms

　　图1。LMP91050方框图

　　图2。LMP91050典型NDIR传感应用电路图

　　SPIO-4精密信号通路控制器板

　　The SPIO-4 is one of several National Semiconductor digital controller/capture boards that are used by multiple evaluation systems. The objective of these software/hardware evaluation systems is to allow our customers to easily and accurately evaluate National s signal-path devices in a lab setting. At the time of SPIO-4 s release, two different evaluation system software (GUIs) make use of this board: the WaveVision-5 and the Sensor AFE. The board ships with the current version of the WaveVision-5 software.

　　In addition to the controller/capture board (i.e., the SPIO-4) and the evaluation GUI software (e.g.,WaveVision-5 or Sensor AFE), the third essential element of an evaluation system is the device or signalpath evaluation board that plugs into the controller board. This eval board is generically referred to as the “DUT board”. Each DUT board comes with its own Users Guide which documents its specific features.

　　Each DUT board also comes with some software that the user must install before using it. In the case of the WaveVision-5 GUI, this software is essentially a device-specific module that adds support for the future device eval boards. In the case of Sensor AFE device family, the eval board comes with a complete, custom Sensor AFE that is specifically paired with that device.

　　The WaveVision-5 and Sensor AFE GUI software have their own Users

　　Guide documents that describe how to interact with the GUI.

　　This User

　　s Guide describes only the SPIO-4 board. The user is expected to refer to this guide only if necessary. The DUT Users

　　Guide and the GUI Users

　　Guide are the primary documents that describehow to work with a National signal-path evaluation board.

　　SPIO-4系统特性：

　　Captures or sources multiple signal-path data streams and transfers them to/from the PC based application software through a USB 2.0 connection (USB1.1 compatible).

　　Supports jumper-less, plug-and-play configuration. The GUI automatically discovers the attached DUT board and loads the appropriate software module for it.

　　Supports a wide variety of signal-path evaluation board through a standardized connector (GPSI-16/GPSI-32).

　　Capable of storing up to 8MBytes of signal-path data.

　　DUT interface can be SPI, I2C or parallel.

　　Powered either by PC via USB or external supply

　　Atmel SAM3U microcontroller (ARM Cortex M3 Core)

　　Available IDE connector for Atmel firmware development environment

　　USB 2.0 port

　　USB-powered

　　Maximum serial clock rate of 80 MHz

　　Xilinx XC6SLX16 FPGA

　　Standard `GPSI-16` connector that allows connection to many National precision signal-path devices

　　图3。SPIO-4精密信号通路控制器板外形图

　　图4。SPIO-4精密信号通路控制器板方框图