TI INA333 ECG心电图应用方案

TI公司的INA333是微功耗零漂移轨到轨精密仪表放大器,采用单一外接电阻可把增益设定在1到1000之间.工作电压低到1.8V(±0.9V),静态电流仅为50uA,有极低的噪音密度(50nV/ Hz),广泛用于桥式放大器,心电图(ECG)放大器,压力传感器,医疗仪器和手提仪表,热电偶放大器和数据采集.本文介绍了INA333的主要性能, 方框图, 基本的连接电路,以及ECG心电图系统方框图,非常低功耗的ECG应用电路和血糖仪应用电路以及数据采集系统电路图.

INA333 Micro-Power (50uA), Zerø-Drift, Rail-to-Rail Out Instrumentation Amplifier
The INA333 is a low-power, precision instrumentation amplifier offering excellent accuracy. The versatile 3-op amp design, small size, and low power make it ideal for a wide range of portable applications.

A single external resistor sets any gain from 1 to 1000. The INA333 is designed to use an industry-standard gain equation: G = 1 + (100k /RG).

The INA333 provides very low offset voltage (25µV, G ≥ 100), excellent offset voltage drift (0.1µV/°C, G ≥ 100), and high common-mode rejection (100dB at G ≥ 100). It operates with power supplies as low as 1.8V (±0.9V), and quiescent current is only 50µA—ideal for battery-operated systems. Using autocalibration techniques to ensure excellent precision over the extended industrial temperature range, the INA333 also offers exceptionally low noise density (50nV/ Hz) that extends down to dc.
The INA333 is available in both MSOP-8 and DFN-8 surface-mount packages and is specified over the TA = -40°C to +125°C temperature range.

主要特性:
LOW OFFSET VOLTAGE: 25µV (max), G=100
LOW DRIFT: 0.1µV/°C, G=100
LOW NOISE: 50nV/ Hz, G=100
HIGH CMRR: 100dB (min), G=10
LOW INPUT BIAS CURRENT: 200pA (max)
SUPPLY RANGE: +1.8V to +5.5V
INPUT VOLTAGE: (V-) +0.1V to (V+) -0.1V
OUTPUT RANGE: (V-) +0.05V to (V+) -0.05V
LOW QUIESCENT CURRENT: 50µA
OPERATING TEMPERATURE: -40°C to +125°C
RFI FILTERED INPUTS
MSOP-8 AND DFN-8 PACKAGES

应用:
BRIDGE AMPLIFIERS
ECG AMPLIFIERS
PRESSURE SENSORS
MEDICAL INSTRUMENTATION
PORTABLE INSTRUMENTATION
WEIGH SCALES
THERMOCOUPLE AMPLIFIERS
RTD SENSOR AMPLIFIERS
DATA ACQUISITION




图1. INA333方框图



图2. INA333基本连接电路




图3.ECG心电图系统方框图




图4.带右腿驱动的ECG放大框图




图5.单电源非常低功耗的ECG应用电路



图6.用于以电池为能源的手持设备的低功耗对数功能的应用电路(血糖仪案例)



图7.用于PT100 RTD的四线3V调理电路(带可编程增益采集系统)