TI ADS1x9x心电图模拟前端(ECG FE)解决方案

中心议题：
    *  TI ADS1x9x心电图模拟前端(ECG FE)解决方案

TI公司的ADS1x9x系列包括ADS1291, ADS1292和ADS1292R器件,是低功耗两路24位心电图模拟前端(ECG FE),集成了可同时取样的24位delta-sigma (ΔΣ) ADC和可编增益放大器(PGA),基准电压源和板上振荡器.每路的功耗仅为335uW,输入参考噪音8 μVPP (150-Hz BW, G = 6),输入偏置电流200pA,数据速率从125SPS到8kSPS,CMMR为-105dB,可编程增益1, 2, 3, 4, 6, 8或12,支持单电源和双极电源,主要用在便携式低功耗医用心电图仪,运动和健美等领域.本文介绍了ADS1x9x主要特性, 功能方框图, 单电源和双极电源工作电路图, ADS1x9xECG-FE演示板主要特性,方框图,电路图,材料清单和PCB元件布局图.

Low-Power, 2-Channel, 24-Bit Analog Front-End for Biopotential Measurements

The ADS1291, ADS1292, and ADS1292R are multichannel, simultaneous sampling, 24-bit, delta-sigma (ΔΣ) analog-to-digital converters (ADCs) with a built-in programmable gain amplifier (PGA), internal reference, and an onboard oscillator.

The ADS1291, ADS1292, and ADS1292R incorporate all features commonly required in portable, low-power medical electrocardiogram (ECG), sports, and fitness applications. ADS1292R enable the creation of scalable medical instrumentation systems at significantly reduced size, power, and overall cost.

The ADS1291, ADS1292, and ADS1292R have a flexible input multiplexer per channel that can be independently connected to the internally-generated signals for test, temperature, and lead-off detection. Additionally, any configuration of input channels can be selected for derivation of the right leg drive (RLD) output signal.

The ADS1292R version includes a fully integrated respiration impedance measurement The devices are packaged in a 5-mm × 5-mm, 32-pin thin quad flat pack (TQFP). Operating temperature is specified from –40℃ to +85℃.

ADS1x9x主要特性:

• Two Low-Noise PGAs and Two High-Resolution ADCs (ADS1292 and ADS1292R)

• Low Power: 335 μW/channel

• Input-Referred Noise: 8 μVPP A(150-Hz BW, G = 6)

• Input Bias Current: 200 pA.

• Data Rate: 125 SPS to 8 kSPS

• CMRR: –105 dB

• Programmable Gain: 1, 2, 3, 4, 6, 8, or 12

• Supplies: Unipolar or Bipolar

– Analog: 2.7 V to 5.25 V

– Digital: 1.7 V to 3.6 V

• Built-In Right Leg Drive Amplifier, Lead-Off Detection, Test Signals t

• Integrated Respiration Impedance Measurement (ADS1292R)

• Built-In Oscillator and Reference

• Flexible Power-Down, Standby Mode

• SPI™-Compatible Serial Interface.

• Operating Temperature Range: –40℃ to +85℃

ADS1x9x应用:

• Medical Instrumentation (ECG) including:

– Patient monitoring: Holter, event, stress, and vital signs including ECG, AED, and Telemedicine

– Sports and fitness (heart rate, respiration, and ECG)
 

• High-Precision, Simultaneous, Multichannel Signal Acquisition

图1.ADS1x9x功能方框图

图2.ADS1x9x单电源工作电路图

图3.ADS1x9x双电源工作电路图

ADS1x9xECG-FE演示板

This demonstration kit models the ADS1192, ADS1292 and ADS1292R. The family of devices are two-channel, 16/24-bit, low-power, integrated analog front-end (AFE) designed for portable electrocardiogram (ECG) and respiration applications. The ADS1x9xECG-FE is intended for prototyping and evaluation. This user’s guide includes a complete circuit description, schematic diagram, and Bill of Materials.

The ADS1x9xECG FE is a demonstration kit for the ADS1292R, a two channel, simultaneous sampling, 24-bit, delta-sigma (ΔΣ) analog-to-digital converter (ADC) with a built-in programmable gain amplifier (PGA), internal reference, and respiration measurement. The ADS1292R chip incorporates all of the features that are commonly required in medical electrocardiogram (EKG/ECG) and electroencephalogram (EEG) and respiratory monitoring applications. The ADS1x9xECG FE is equipped with a MSP430F5529 micro-controller giving the user all the circuitry needed to run the ADC. The board can be used with a variety of patient simulators and allows the user to take advantage of the flexible input multiplexer which can be independently connected to the internally-generated signals for test, temperature, and lead-off detection. Software is available from Texas Instruments to allow the evaluation platform to run with a PC user interface.
 

ADS1x9xECG-FE演示板主要特性:

Easy-to-use evaluation software for Microsoft™ Windows XP or Windows 7

Built-in analysis tools including oscilloscope, FFT, and histogram displays

Flexible input configurations

Integrated Respiration Impedance

Digital Low Pass, High Pass, and 50/60Hz notch filters for post processing

Real time data streaming from the demo board to the PC

Ability to export data in simple test files for post processing

图4. ADS1x9xECG-FE演示板外形图

The board can be assembled with any of these chips. ADS1292, ADS1292R and ADS1192 demonstration kits are available. The MSP430 firmware and PC application are designed to automatically detect the installed part and configure to accommodate the part.

该版本所支持的特性:

1. Four electrode ECG cable support

2. View six ECG Leads: Lead I, Lead II, Lead III, Lead aVR, Lead aVL, Lead aVF and respiration channel (ADS1292R only) .

3. Two modes of operation: Evaluation and Live ECG / Respiration

4. Acquire data at up to 8 kHz in Evaluation mode

5. Current based Lead off detection

6. USB based power and PC application connectivity

7. Access to all ADS1x9x registers via an easy to use GUI.

8. Built-in time domain, histogram, FFT and ECG / Resp related analysis on the PC application

9. Live ECG with heart rate calculation.

10. Live Respiration wave with respiration rate calculation

11. USB based firmware upgrade option

12. MSP430 Firmware debugging using ez430 USB emu

ADS1x9xECG-FE演示板主要特性:

The key features of the ADS1x9x analog front end demonstration board are:

• Based on MSP430F5529

• ADS1192 and ADS1292 suitable for six leads of ECG: Lead I, Lead II, Lead III, Lead aVR, Lead aVL, or Lead aVF

• ADS1292R suitable for one lead of ECG (Lead I) and respiration channel

• Low power consumption (350 Micro Watt/channel)

• Data Rate ranges from 125 SPS to 8 kSPS

• Unipolar Operation

• Lead off detection circuitry

• On chip oscillator and reference

• On chip RLD amplifier
 

• SPI data interface

• 8Gb NAND Flash support

图5.ADS1x9xECG-FE演示板框图

图6.ADS1x9xECG-FE演示板电路图(1)

图7.ADS1x9xECG-FE演示板电路图(2)
 

图8.ADS1x9xECG-FE演示板电路图(3)

图9.ADS1x9xECG-FE演示板电路图(4)

图10.ADS1x9xECG-FE演示板电路图(5)

图11.ADS1x9xECG-FE演示板电路图(6)
 

ADS1x9xECG-FE演示板材料清单(BOM):



图12.ADS1x9xECG-FE演示板元件布局图:顶层

图13.ADS1x9xECG-FE演示板元件布局图:底层