Texas Instruments has now developed the INA333 which is the industry's lowest power zero-drift instrumentation amplifier. The device improves accuracy and extends battery life for a host of medical devices including electro-physiological electrodes like ECG EEG and EMG.
The INA333 is a low power, relatively low bandwidth, differential-input amplifier. It improves accuracy and stability while extending battery life in a variety of precision, low-power applications such as portable medical, data acquisition, weigh scales and handheld instrumentation. Its circuit applications focus on differential measurements from sensors or transducers.
The types of sensors that would connect to the two INA333 inputs (Vin+ and Vin) include: Electro-physiological electrodes like ECG, EEG and EMG used to monitor heart, brain and muscle and heart rate monitors. Pressure bridges used in blood pressure instruments and Weigh scale bridges used to monitor body weight and mass plus movement force and torque). Temperature sensors, Flow devices used to check breathing or respiratory rate and Chemical cells conditions like blood-gas, respiratory-gas, body fluids particularly blood, urine, sweat, water.
There has been a growing demand from the medical devices manufacturers for higher precision combined with lower power and lower operating voltages in order to increase the performance and value of their sensor signal acquisition systems." The INA333 leverages our expertise in analog signal conditioning to deliver a new standard for precision, low-power instrumentation amplifiers and enable our customers to gain a competitive advantage in the market," informed Apoorva Awasthy, business development manager, High Performance Analog, Texas Instruments India.
"The INA333 joins TI's state-of-the-art signal chain solution for precision, low-power applications: analog-to-digital converters such as the ADS1158; operational amplifiers such as the OPA333; digital isolators such as the ISO721; and temperature sensors such as the TMP102. It is also optimized to work with TI's MSP430 ultra-low power microcontroller family, added Awasthy.
Further, the INA333 utilizes TI's zero-drift technology which incorporates a proprietary switched-capacitor notch filter to eliminate chopping noise and provide very low input voltage noise of 50 nV/rt-Hz. The device features a versatile three op amp architecture to simplify design and reduce board space.
With only 75 µA of quiescent current and operation on power supplies as low as 1.8 V, the INA333 maximizes power efficiency. Low offset voltage of 25 µV and offset drift of 0.1 µV/C deliver excellent accuracy and long-term stability. Applications with high impedance sources will benefit from low input bias current of 200 pA.
Special filters have been integrated in series with the inputs of the INA333 to reduce radio frequency (RF) interference. This can dramatically reduce susceptibility to RF-induced offset voltage variations, which can be a critical advantage in applications that require DC stability, such as weigh scales.