•  
• EDN Europe MAGAZINE
•  
• Free SUBSCRIPTION
• Subscription Renewal
• View Media Kit

• EDN
• EDN Australia
• EDN Asia
• EDN China
• EDN Japan

Instrumentation amp for high common-mode-voltages

Texas Instruments has introduced a part it describes as the most accurate available difference amplifier for high commonmode- voltage applications up to +275 V. You can double measurement accuracy compared to prior devices, with common-mode rejection ratio (CMRR) of 100 dB, or a guaranteed 90 dB CMRR performance in harsh, high temperature environments up to 125°C. The amplifier also lowers initial gain error by one-third and increases slew rate by a factor of two. You might use the amplifier, TI suggests, in high commonmode- voltage applications such as high-voltage current sensing, battery cell voltage monitoring in photovoltaic, telecom, electric vehicles, and alternative energy applications; power-supply current monitoring; and motor control. Input common-modevoltage from -275 V to +275 V enables accurate monitoring of signals present in high common-mode voltages, eliminating the need for multiple supply sources and analogue isolation components. Large-signal bandwidth is 500 kHz, and maximum initial gain error is 0.02% for better accuracy. An evaluation module (INA149EVM) costs $49, there is a TINA-TI SPICE model to simulate device performance, and the INA149 in a 4.9 x 6-mm SOIC package costs $2.70 (1000).

—by Graham Prophet

TI, www.ti.com/ina149-preu