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High Common Mode Voltage Difference Amplifier


Features for the INA149


  • Common-Mode Voltage Range: ±275 V
  • Minimum CMRR: 90 dB from –40°C to +125°C
  • DC Specifications:
    • Maximum Offset Voltage: 1100 µV
    • Maximum Offset Voltage Drift: 15 µV/°C
    • Maximum Gain Error: 0.02%
    • Maximum Gain Error Drift: 10 ppm/°C
    • Maximum Gain Nonlinearity: 0.001% FSR
  • AC Performance:
    • Bandwidth: 500 kHz
    • Typical Slew Rate: 5 V/µs
  • Wide Supply Range: ±2.0 V to ±18 V
    • Maximum Quiescent Current: 900 µA
    • Output Swing on ±15-V Supplies: ±13.5 V
  • Input Protection:
    • Common-Mode: ±500 V
    • Differential: ±500 V


Description for the INA149


The INA149 is a precision unity-gain difference amplifier with a very high input common-mode voltage range. It is a single, monolithic device that consists of a precision op amp and an integrated thin-film resistor network. The INA149 can accurately measure small differential voltages in the presence of common-mode signals up to ±275 V. The INA149 inputs are protected from momentary common-mode or differential overloads of up to 500 V.

In many applications, where galvanic isolation in not required, the INA149 can replace isolation amplifiers. This ability can eliminate costly isolated input side power supplies and the associated ripple, noise, and quiescent current. The excellent 0.0005% nonlinearity and 500-kHz bandwidth of the INA149 are superior to those of conventional isolation amplifiers.

The INA149 is pin-compatible with the INA117 and INA148 type high common-mode voltage amplifiers and offers improved performance over both devices. The INA149 is available in the SOIC-8 package with operation specified over the extended industrial temperature range of –40°C to +125°C.