Maxim MAX30001超低功耗生物電勢(shì)和阻抗AFE的解決方案詳解

Maxim公司的MAX30001是超低功耗單路生物電勢(shì)（ECG，R-R，節(jié)奏檢測(cè)）和生物阻抗（BioZ）模擬前端（AFE）。生物電勢(shì)通路提供心電圖（ECG）波形，心率和起搏器邊沿檢測(cè)，而生物阻抗通路則能夠測(cè)量呼吸。兩個(gè)通路具有ESD保護(hù)，EMI濾波，內(nèi)部電極偏壓，DC導(dǎo)聯(lián)脫落檢測(cè)，超低功耗，待機(jī)模式導(dǎo)聯(lián)連接檢測(cè)和內(nèi)置自測(cè)校準(zhǔn)電壓以及高輸入阻抗，低噪音，高CMRR，可編增益，各種低通和高通濾波器選擇和高分辨率模數(shù)轉(zhuǎn)換器。主要用在心律不齊檢測(cè)的單導(dǎo)聯(lián)事件監(jiān)測(cè)器，住院/門診監(jiān)測(cè)的單引線無(wú)線貼片，健身胸帶心率監(jiān)視器，呼吸和水化監(jiān)視器，基于阻抗的心率檢測(cè)，生物認(rèn)證和按需ECG應(yīng)用。本文介紹了MAX30001主要優(yōu)勢(shì)和特性，功能框圖，應(yīng)用電路，以及評(píng)估板MAX30001 EVS主要特性，電路圖，材料清單和PCB設(shè)計(jì)圖。

The MAX30001 is a complete， biopotential and bioimpedance （BioZ）， analog front-end （AFE） solution for wearable applications. It offers high performance for clinical and fitness applications， with ultra-low power for long battery life. The MAX30001 is a single biopotential channel providing electrocardiogram （ECG） waveforms， heart rate and pacemaker edge detection， and a single bioimpedance channel capable of measuring respiration.

The biopotential and bioimpedance channels have ESD protection， EMI filtering， internal lead biasing， DC leads-off detection， ultra-low-power， leads-on detection during standby mode， and extensive calibration voltages for built-in self-test. Soft power-up sequencing ensures no large transients are injected into the electrodes. Both channels also have high input impedance， low noise， high CMRR， programmable gain， various low-pass and high-pass filter options， and a high resolution analog-to-digital converter. The biopotential channel is DC coupled， can handle large electrode voltage offsets， and has a fast recovery mode to quickly recover from overdrive conditions， such as defibrillation and electro-surgery. The bioimpedance channel includes integrated programmable current drive， works with common electrodes， and has the flexibility for 2 or 4 electrode measurements. It also has AC lead off detection.The MAX30001 is available in a 28-pin TQFN and 30-bump wafer-level package （WLP）， operating over the0℃ to +70℃ commercial temperature range.

MAX30001主要優(yōu)勢(shì)和特性：

Clinical-Grade ECG and BioZ AFE with High Resolution Data Converter15.9 Bits ENOB with 3.1μVPP （typ） Noise for ECG

17 Bits ENOB with 1.1μVPP Noise for BioZ

Better Dry Starts Due to Much Improved Real World CMRR and High Input ImpedanceFully Differential Input Structure with CMRR 》 100dB

Offers Better Common-Mode to Differential Mode Conversion Due to High Input Impedance

High Input Impedance 》 1GΩ for Extremely Low Common-to-Differential Mode

Minimum Signal Attenuation at the Input During Dry Start Due to High Electrode Impedance

High DC Offset Range of ±650mV （1.8V， typ） Allows to Be Used with Wide Variety of Electrodes

High AC Dynamic Range of 65mVPP for ECG and 100mVPP for BioZ Will Help Prevent Saturation in the Presence of Motion/Direct Electrode Hits

Longer Battery Life Compared to Competing Solutions85μW at 1.1V Supply Voltage for ECG

158μW at 1.1V Supply Voltage for BioZ

Leads-On Interrupt Feature Allows to KeepμC in Deep Sleep Mode Until Valid Lead Condition is DetectedLead-On Detect Current： 0.7μA （typ）

Built-In Heart Rate Detection with Interrupt Feature Eliminates the Need to Run HR Algorithm on the μControllerRobust R-R Detection in High Motion Environment at Extremely Low Power

Configurable Interrupts Allows the μC Wake-Up Only on Every Heart Beat Reducing the Overall System Power

High Accuracy Allows for More Physiological Data Extractions

32-Word ECG and 8-Word BioZ FIFOs Allows the MCU to Stay Powered Down for 256ms with Full Data Acquisition

High-Speed SPI Interface

Shutdown Current of 0.5μA （typ）

MAX30001應(yīng)用：

Single-Lead Event Monitors for Arrhythmia Detection

Single-Lead Wireless Patches for In-Patient/Out-Patient Monitoring

Chest Band Heart Rate Monitors for Fitness Applications

Bio Authentication and ECG-On-Demand Applications

Respiration and Hydration Monitors

Impedance Based Heart Rate Detection

圖1.MAX30001功能框圖

圖2.MAX30001應(yīng)用電路圖：兩電極ECG和呼吸監(jiān)視器

圖3.MAX30001應(yīng)用電路圖：四電極ECG和呼吸監(jiān)視器

評(píng)估板MAX30001 EVS

The MAX30001 evaluation system （EV system） provides a single platform to evaluate the functionality and features of the MAX30001 with Biopotential （ECG， R-to-R， and Pace Detection） and Bioimpedance （BioZ） measurement capabilities. The EV system includes a MAX30001 evaluation kit （EV kit） and a MAX32630FTHR Cortex-M4F microcontroller for wearables. The MAX32630FTHR provides power to the MAX30001 EV kit and contains the firmware necessary to use the EV kit GUI program. The EV kit ships with jumpers installed and supply voltages set to typical operating values. Optional connections exist which can be shunted to make use of different functionalities.

評(píng)估板MAX30001 EVS主要特性：

Convenient Platform to Evaluate the MAX30001

Many Easy-to-Reach Test Points

Measure Individual Supply Currents

Touchproof Cable Connectors

Windows? 7/8/10 Compatible GUI software

Fully Assembled and Tested

Facilitates IEC 60601-2-47 Compliance Testing

Ultra-Low-Power Design

評(píng)估板MAX30001 EVS包括：

MAX30001 EV kit

MAX32630FTHR

USB A to micro-USB cable

Three （3） ECG cables

圖4.評(píng)估板MAX30001 EVS外形圖

圖5.評(píng)估板MAX30001 EVS簡(jiǎn)化電路圖

圖6.評(píng)估板MAX30001 EVS電路圖（1）

圖7.評(píng)估板MAX30001 EVS電路圖（2）

評(píng)估板MAX30001 EVS材料清單：

圖8.評(píng)估板MAX30001 EVS PCB設(shè)計(jì)路圖（1）：頂層絲印

圖9.評(píng)估板MAX30001 EVS PCB設(shè)計(jì)路圖（2）：頂層

圖10.評(píng)估板MAX30001 EVS PCB設(shè)計(jì)路圖（3）：層2

圖11.評(píng)估板MAX30001 EVS PCB設(shè)計(jì)路圖（4）：層3

圖12.評(píng)估板MAX30001 EVS PCB設(shè)計(jì)路圖（5）：底層

圖13.評(píng)估板MAX30001 EVS PCB設(shè)計(jì)路圖（6）：底層絲印