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[原创] Maxim MAXM86161单电源光学模块HR和SpO2测量方案

关键词:工业测量 医疗电子 数据收集系统 传感器

时间:2019-08-06 10:36:18       来源:中电网

摘要: Maxim公司的MAXM86161是超低功耗全集成的单电源光学数据采集系统.发送端, MAXM86161具有三个可编大电流的LED驱动器;而接收端, MAXM86161包括高效率PIN光电二极管和光读出通路. 光读出通路具有低噪音信号调理模拟前端(AFE),包括19位ADC,一个行业领先的环境光取消(ALC)电路,栅状检测和替代算法.由于MAXM86161的低功耗,紧凑的尺寸,容得和灵活使用,业界一流的环境光抑制功能,使得器件非常适合各种光学检测应用如心率检测和脉搏血氧仪.MAXM86161暗电流噪音小于50pA RMS,具有三个低噪音8位LED电流DAC, 白卡回环测试中的动态范围大于89dB,120Hz时环境光抑制大于78dB,光电管环境光电流大于100μA,工作环境温度-40°C到 +85°C.主要用在耳内应用,移动应用的微型包装,光心率检测, 氧饱和度(SpO2)检测和心率变异性(HRV)连续监测.本文介绍了MAXM86161主要优势和特性,简化框图以及评估系统MAXM86161EVSYS#主要特性,框图和包括MAXM86161OSBFLEX和MAXSensorBLE的电路图,材料清单和PCB设计图.



 The MAXM86161 is an ultra-low-power, completely integrated, optical data-acquisition system. On the transmitter side, the MAXM86161 has three programmable high-current LED drivers. On the receiver side, MAXM86161 consists of a high efficiency PIN photo-diode and an optical readout channel. The optical readout has a low-noise signal conditioning analog front-end (AFE), including 19-bit ADC, an industry-lead ambient light cancellation (ALC) circuit, and a picket fence detect and replace algorithm. Due to the low power consumption, compact size, easy, flexible-to-use, and industry lead ambient light rejection capability of the MAXM86161, the device is ideal for a wide variety of optical sensing applications such as heart rate detection and pulse oximetry.

The MAXM86161 operates on a 3.0V to 5.5V VLED single supply voltage. It supports a standard compatible interface and fully autonomous operation. Each device has a large 128-word built-in FIFO. The MAXM86161 is available in compact 2.9mm x 4.3mm x 1.4mm, 14-pin OLGA package.

MAXM86161主要优势和特性:

Complete Single-Channel Optical Data Acquisition System

Built-In Algorithm Further Enhances Rejection of Fast Ambient Transients

Optimized Architecture for Reflective Heart Rate and SpO2 Monitoring

Low Dark Current Noise of < 50pA RMS (Sample-to- Sample Variance)

Lower Effective Dark Current Noise Achievable through Multiple Sample Modes and On-Chip Averaging

High-Resolution 19-bit Charge Integrating ADC

Three Low-Noise 8-Bit LED Current DACs

Excellent Dynamic Range > 89dB in White Card Loop-Back Test (Sample-to-Sample Variance)

Excellent Ambient Range and Rejection Capability

> 100μA Ambient Photodetector Current

> 70dB Ambient Rejection at 120Hz

Ultra-Low-Power Operation for Wearable Devices Low-Power Operation, Optical Readout Channel < 10μA, Typical at 25sps

Short Exposure Integration Period of 14.8μs, 29.4μs, 58.7μs, 117.3μs

Low Shutdown Current = 1.6μA (typ)

Miniature 2.9mm x 4.3mm x 1.4mm, 14-pin OLGA Package

-40°C to +85°C Operating Temperature Range

MAXM86161应用: 

Optimized for In-Ear Applications

Miniature Package for Mobile Applications

Optimized Performance to Detect: Optical Heart Rate

Oxygen Saturation (SpO2)

Continuous Monitoring for HRV



图1. MAXM86161简化框图

评估系统MAXM86161EVSYS#

 The MAXM86161EVSYS# evaluation system (EV system) allows for the quick evaluation of the MAXM86161 integrated optical module for applications at various sites on the body, particularly in-ear and mobile applications. The MAXM86161 device communicates using a standard I2C-compatible interface to Maxim’s on-board MAX32664 Biometric Sensor Hub microcontroller (used for Maxim’s algorithm evaluation) or in a pass-through mode for raw data collection. The MAXM86161 device consists of three optical readout channels that can be individually controlled (Green, Red, and IR). The EV system allows for flexible configurations to allow testing of various features of the sensor. Moreover, it helps the user quickly learn how to configure and use the MAXM86161 device.

The primary EV system consists of three circuit board assemblies (MAXSensorBLE_EVKIT, MAXM86161OSBFLEX, and the Cypress CY5677 Dongle), one USB-C to USB-A connector cable, and a Lithium Polymer battery. These components are highlighted in Figure 3 below. In addition, two programming circuit boards (MAXM86161_MAX32630_PRGMR_ASSY, and the MAXREFDES100HDK) and one USB-B Micro-to- USB-A Male USB cable are provided for firmware updates if needed.

The EV system can be powered using a USB-C supply or LiPo Battery and comes with a MAXM86161EFD+ device in a 14-pin OLGA package.

The MAXM86161OSBFLEX Flex-Rigid circuit board has a Maxim Integrated MAX32664 Biometric Sensor Hub microcontroller device installed. This Sensor Hub can be used to implement Maxim’s HR/SpO2 Algorithm for evaluation. The MAXM86161 GUI PC application code that allows evaluation of both the MAXM86161EVSYS# and the MAX32664 Sensor Hub is available in the MAXM86161EVSYS# EV System Design Resources tab.

评估系统MAXM86161EVSYS#主要特性:

Performance Evaluation of the MAXM86161 Sensor (e.g., SNR, Dark Current, Noise, etc.)

Performance Evaluation of Maxim Algorithms for Power Optimization, Heart Rate (HR), SpO2 (Peripheral Capillary Oxygen Saturation), etc. Using the On-Board MAX32664GWEC+ Biometric Sensor Hub Microcontroller

Facilitates Understanding of MAXM86161 Architecture and Solution Strategy

Real-Time Monitoring and Data Logging Capabilities

On-Board Accelerometer

Bluetooth™ LE for wireless data collection



图2. 评估系统MAXM86161EVSYS#框图



图3.评估系统MAXM86161EVSYS#硬件建立图(Micro PCB)



图4.评估系统MAXM86161EVSYS#硬件建立图(传感器PCB)



图5.评估系统MAXM86161OSBFLEX电路图





图6.评估系统MAXSensorBLE电路图(1)



图6.评估系统MAXSensorBLE电路图(2)



图7.评估系统MAXSensorBLE电路图(3)



图8.评估系统MAXSensorBLE电路图(4)

评估系统MAXM86161EVSYS#材料清单:





图9.评估系统MAXM86161OSBFLEX PCB设计图:左:顶层丝印;右:层3





图10.评估系统MAXM86161OSBFLEX PCB设计图:左:顶层;右:底层



图11.评估系统MAXM86161OSBFLEX PCB设计图:左:层2;右:底层





图12.评估系统MAXSensorBLE PCB设计图:左:顶层丝印;右:层3



图13.评估系统MAXSensorBLE PCB设计图:左:顶层;右:层4



图14.评估系统MAXSensorBLE PCB设计图:左:层2;右:层5



图15.评估系统MAXSensorBLE PCB设计图:左:层6;右:层9



图16.评估系统MAXSensorBLE PCB设计图:左:层7;右:层10



图17.评估系统MAXSensorBLE PCB设计图:左:层8;右:层11



图18.评估系统MAXSensorBLE PCB设计图:左:底层;右:底层丝印

详情请见:

https://datasheets.maximintegrated.com/en/ds/MAXM86161.pdf

https://datasheets.maximintegrated.com/en/ds/MAXM86161EVSYS.pdf

MAXM86161.pdf

MAXM86161EVSYS.pdf

MAXM86161ADPTR.zip

MAXM86161OSBFLEX.zip

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