原标题：TI TIDA-00378PM2.5粒子传感器模拟前端参考设计

　　TI公司的TIDA-00378是PM2.5和PM10粒子传感器模拟前端(AFE)参考设计,基于OPA320单个和OPA2320双路运算放大器,PM2.5 (<2.5µm)和PM10 (<10µm)粒子检测和尘埃测量范围从340 x 103到991 x 103 pcs/ft3 (12 - 35 pcs/cm3),AFE输入电压3.3V,平均电流13mA,主要用在空气质量和气体检测以及环境传感器.本文介绍了OPA320主要特性,以及TIDA-00378主要特性和指标,传感器框图和电路图,材料清单和PCB设计图.

　　The OPA320 (single) and OPA2320 (dual) are a new generation of precision, low-voltage CMOS operational amplifiers optimized for very low noise and wide bandwidth while operating on a low quiescent current of only 1.45mA.

　　The OPA320 series is ideal for low-power, single-supply applications. Low-noise (7nV/√Hz) and high-speed operation also make them well-suited for driving sampling analog-to-digital converters (ADCs). Other applications include signal conditioning and sensor amplification.

　　The OPA320 features a linear input stage with zero-crossover distortion that delivers excellent common-mode rejection ratio (CMRR) of typically 114dB over the full input range. The input common-mode range extends 100mV beyond the negative and positive supply rails. The output voltage typically swings within 10mV of the rails.

　　In addition, the OPAx320 have a wide supply voltage range from 1.8V to 5.5V with excellent PSRR (106dB) over the entire supply range, making them suitable for precision, low-power applications that run directly from batteries without regulation.

　　The OPA320 (single version) is available in a SOT23-5 package; the OPA320S shut-down single version is available in an SOT23-6 package. The dual OPA2320 is offered in SO-8, MSOP-8, and DFN-8 packages, and the OPA2320S (dual with shut-down) in an MSOP-10 package.

　　OPA320主要特性:

　　Precision with Zero-Crossover Distortion:

　　Low Offset Voltage: 150µV (max)

　　High CMRR: 114dB

　　Rail-to-Rail I/O

　　Low Input Bias Current: 0.9pA (max)

　　Low Noise: 7nV/√Hz at 10kHz

　　Wide Bandwidth: 20MHz

　　Slew Rate: 10V/µs

　　Quiescent Current: 1.45mA/ch

　　Single-Supply Voltage Range: 1.8V to 5.5V

　　OPA320S, OPA2320S:

　　IQ in Shutdown Mode: 0.1µA

　　Unity-Gain Stable

　　Small Packages:

　　SOT23, MSOP, DFN

　　OPA320应用:

　　High-Z Sensor Signal Conditioning

　　Transimpedance Amplifiers

　　Test and Measurement Equipment

　　Programmable Logic Controllers (PLCs)

　　Motor Control Loops

　　Communications

　　Input/Output ADC/DAC Buffers

　　Active Filters

　　PM2.5粒子模拟前端解决方案TIDA-00378

　　The TIDA-00378 TI Design provides an analog front-end solution for measuring PM2.5 and PM10 particle matter. The design detects the light scattered by particles suspended in air. A sample software algorithm is provided to convert the analog output of the design into a particle size and concentration measurement. Test result data for cigarette smoke, Arizona dust, and mulberry pollen is provided along with all software and hardware design files.

　　Different methods exist to measure the amount of particle matter (PM) suspended in air. Optical-basedPM measurement instruments utilize the properties of absorption and light scattering to measure particlecount, size, and concentration. Although these instruments differ in complexity, accuracy, and cost, theyall share the same basic components: a light source directed at the particles, a detector to measure thelight scattered (or absorbed) by the particles, an AFE to interface with the detector, and signal processingto analyze the output of the AFE.

　　The PM2.5/PM10 Particle Sensor Analog Front-End Design is capable of detecting particle matter with adiameter between 2.5 and 10 μm (PM10) and particle matter with a diameter less than 2.5 μm (PM2.5). ThisTI Design filters and amplifies the output from a photodiode and produces an output signal that can beprocessed by a microcontroller. The transimpedance stage uses an OPA2320 dual-package precisionCMOS operational amplifier (op amp) and an INA132 single-supply difference amplifier to convert theoutput current of the photodetector into a voltage. The filter and amplification stages use the OPA2320 opamp with a tunable gain and basic RC-filters. A light-emitting diode (LED) driver with an adjustable LEDcurrent is also included in the design.

　　The design is implemented on a single-ended, four-layer board of a size of 44 × 19 mm with a build-ofmaterials(BOM) count of 37 components. The TI Design interfaces with the photodiode and LED of anexisting optical chamber through dedicated pads on the board. This TI Design was tested using pollen,dust, and smoke particles—the full test procedure and results are included in this design guide.

　　This design guide addresses component selection, design theory, and test results of the entire TI Designsystem. The information provided in this design guide gives system designers a fully-tested referencedesign, which can be easily modified to meet different system requirements.

　　图1.PM2.5粒子模拟前端解决方案TIDA-00378外形图

　　TIDA-00378主要特性:

　　Analog front-end design for PM2.5 (<2.5µm) and PM10 (<10µm) particle detection and countDust measurement range from 340 x 103 to 991 x 103 pcs/ft3 (12 to 35 pcs/cm3) at 75% accuracyZero-volt bias to minimize photodetector noise and stabilize performance over temperatureInstrumentation amplifier topology to reject external noise sourcesLow noise, low input bias current,low offset op-amps with rail-to-rail output to maintain high SNR and increase output dynamic rangeTested against Arizona dust, mulberry pollen,and cigarette smoke using adapted ANSI/AHAM AC-1-2013 test standardFull algorithm source code for PM2.5 and PM10 calculation for customization and portingApplications

　　Air Quality and Gas Detection

　　Environmental Sensor

　　图2.粒子传感器框图

　　TIDA-00378主要特性和指标:

　　PM2.5粒子模拟前端解决方案TIDA-00378材料清单: