中国电子技术网

设为首页 网站地图 加入收藏

 

[原创] ADI ADPD4001多模式传感器前端解决方案

关键词:传感器 可穿戴

时间:2019-08-06 10:29:33       来源:中电网

摘要:ADI公司的ADPD4000/ADPD4001是完整的多模式传感器前端,模拟高达8个LED和测量高达八个单独电流输入的返回信号,可提供12个时隙,使得每个取样周期可进行12个单独测量.数据输出和功能配置在ADPD4001采用I2C接口而在ADPD4000采用SPI接口进行;控制电路包括灵活的LED信令和同步检测.器件采用1.8V模拟核,1.8V/3.3V兼容的数字输入/输出(I/O).模拟前端(AFE)能抑制异步调制干扰特别是环境光的信号偏移,从而消除光滤波器或外部控制DC消除电路. ADPD4000/ ADPD4001可提供多种工作模式,能成为传感器集线器,用于光二极管,双电位电极,电阻,电容和温度传感器的同步测量.采用内部振荡器的灵活取样频率从0.004Hz到9kHz,集成了片上数字滤波器.发送和接收信号链的SNR为90dB,环境光抑制高达1kHz时为60dB,总LED驱动电流400A.主要用在可穿戴健康和健美监视器如心率监视器(HRM),心率变异度(HRV),应力,血压估计, SpO2,水化和身体组分;工作监视器如CO, CO2,烟雾和气溶胶探测以及家庭病人监视器.本文介绍了ADPD4000/ADPD4001主要特性,功能框图以及评估板EVAL-ADPD4000Z-PPG主要特性,电路图和PCB设计图.



 The ADPD4000/ADPD4001 operate as a complete multimodal sensor front end, stimulating up to eight LEDs and measuring the return signal on up to eight separate current inputs. Twelve time slots are available, enabling 12 separate measurements per sampling period.

The data output and functional configuration utilize an I2C interface on the ADPD4001 or a serial port interface (SPI) on the ADPD4000. The control circuitry includes flexible LED signaling and synchronous detection. The devices use a 1.8 V analog core and 1.8 V/3.3 V compatible digital input/output (I/O).

The analog front end (AFE) rejects signal offsets and corruption from asynchronous modulated interference, typically from ambient light, eliminating the need for optical filters or externally controlled dc cancellation circuitry. Multiple operating modes are provided, enabling the ADPD4000/ ADPD4001 to be a sensor hub for synchronous measurements of photodiodes, biopotential electrodes, resistance, capacitance, and temperature sensors.

The ADPD4000/ADPD4001 are available in a 3.11 mm × 2.14 mm, 0.4 mm pitch, 33-ball WLCSP and 35-ball WLCSP.

ADPD4000/ADPD4001主要特性:

Multimodal analog front end

8 input channels with multiple operation modes to accommodate the following measurements: PPG, ECG, EDA, impedance, and temperature

Dual channel processing with simultaneous sampling

12 programmable time slots for synchronized sensor measurements

Flexible input multiplexing to support differential and single-ended sensor measurements

8 LED drivers, 4 of which can be driven simultaneously

Flexible sampling rate from 0.004 Hz to 9 kHz using internal oscillators

On-chip digital filtering

SNR of transmit and receive signal chain: 90 dB

Ambient light rejection: 60 dB up to 1 kHz

400 mA total LED drive current

Total system power dissipation: 50 μW (combined LED and AFE power), continuous PPG measurement at 75 dB SNR, 25 Hz ODR, 100 nA/mA CTR

SPI and I2C communications supported

256-byte FIFO

ADPD4000/ADPD4001应用:

Wearable health and fitness monitors: heart rate monitors (HRMs), heart rate variability (HRV), stress, blood pressure estimation, SpO2, hydration, body composition

Industrial monitoring: CO, CO2, smoke, and aerosol detection

Home patient monitoring



图1. ADPD4000/ADPD4001功能框图

评估板EVAL-ADPD4000Z-PPG

The EVAL-ADPD4000Z-PPG evaluation board provides users with a simple means of evaluating the ADPD4000/ADPD4001 photometric front end.

The EVAL-ADPD4000Z-PPG evaluation board implements a simple discrete optical design for vital signs monitoring applica-tions, specifically wrist-based photoplethysmography (PPG).

 The EVAL-ADPD4000Z-PPG has three green light emitting diodes (LEDs), one infrared (IR), and one red LED, all separately driven. A single 7 mm2 photodiode (PD) is populated on the board. The PD has no optical filter coating. However, a pin for pin alternative device with an IR block filter is available.

The full evaluation system includes the Wavetool Evaluation Software graphical user interface (GUI) that provides users with low level register access and high level system configurability. Raw data streamed to this tool can be displayed in real time with limited latency. Views are provided for both frequency and time domain analysis.

A user datagram protocol (UDP) transfer capability from the Wavetool Evaluation Software (available for download on the EVAL-ADPD4000Z-PPG product page) allows data stream connections and register configurability to external analysis programs, such as LabVIEW® or MATLAB®, in real time.

The EVAL-ADPD4000Z-PPG board is powered by the EVAL-ADPDUCZ microcontroller board (obtained from the EVAL-ADPD4000Z-PPG product page). In addition to the power requirements, serial port interface (SPI) (default) or I2C data streams are received from the ADPD4000 by the microcontroller. A ribbon cable connects the two boards. The microcontroller repackages the data, sending it to a virtual serial port over the USB to the PC, displayed on the Wavetool Evaluation Software. The EVAL-ADPD4000Z-PPG can also be connected directly to the microcontroller development system of the user, using the SPI for the ADPD4000 (or I2C for the ADPD4001).

The ADPD4000/ADPD4001 data sheet, available at www.analog.com, provides full specifications for the ADPD4000/ADPD4001. Consult the ADPD4000/ADPD4001 data sheet in conjunction with this user guide when using the EVAL-ADPD4000Z-PPG.

评估板EVAL-ADPD4000Z-PPG主要特性:

Board supports ADPD4000 and ADPD4001 population

ADPD4000 (SPI) is the default board population

All inputs and outputs are accessible to the user

3 separately driven green LEDs included

1 red and 1 IR LED included

Metal baffle to block optical crosstalk

Works with the Wavetool Evaluation Software allowing

Time domain graphing and logging

Frequency domain graphing

Statistical analysis

Data streaming to other applications

评估板EVAL-ADPD4000Z-PPG包括:

EVAL-ADPD4000Z-PPG evaluation board

Ribbon cable

Wrist strap, with hook and loop fastener



图2. 评估板EVAL-ADPD4000Z-PPG电路图(1)



图3. 评估板EVAL-ADPD4000Z-PPG电路图(2)



图4. 评估板EVAL-ADPD4000Z-PPG外形图(顶层)



图5. 评估板EVAL-ADPD4000Z-PPG外形图(底层)



图6. 评估板EVAL-ADPD4000Z-PPG和EVAL-ADPDUCZ连接图



图7. 评估板EVAL-ADPD4000Z-PPG PCB设计图:顶层和丝印



图8. 评估板EVAL-ADPD4000Z-PPG PCB设计图:层2,地



图9. 评估板EVAL-ADPD4000Z-PPG PCB设计图:层3,电源



图10. 评估板EVAL-ADPD4000Z-PPG PCB设计图:层4,内部信号



图11. 评估板EVAL-ADPD4000Z-PPG PCB设计图:层5,地



图12. 评估板EVAL-ADPD4000Z-PPG PCB设计图:底层,光学



图13. 评估板EVAL-ADPD4000Z-PPG PCB设计图:底层,反向丝印图



图14. 评估板EVAL-ADPD4000Z-PPG PCB设计图:跳线和连接器

详情请见:

https://www.analog.com/media/en/technical-documentation/data-sheets/ADPD4000-4001.pdf

https://www.analog.com/media/en/technical-documentation/user-guides/EVAL-ADPD4000Z-PPG-UG-1529.pdf

ADPD4000-4001.pdf

EVAL-ADPD4000Z-PPG-UG-1529.pdf

 

  • 分享到:

 

猜你喜欢