Op amp offers highest precision for industrial measurements

January 23, 2014 // By Graham Prophet
TI's 36-V rail-to-rail input/output op amp combines low offset and drift with fast settling to improve precision ADC performance.

Texas Instruments claims to have the first 36-V rail-to-rail input and output (RRIO) operational amplifier (op amp) to achieve precision offset voltage and drift without using auto-zero techniques. The OPA192 achieves stable offset voltage drift over the full specified temperature range, which eliminates the need for system level calibration.

Fast settling and high-output drive, combined with precision, allows you to use the device to drive ADCs in high-voltage, precision data acquisition systems including test and measurement, and industrial sensors and controls.

Features include;

  1. New levels of precision: using e-Trim technology, TI's package-level trimming architecture, the device provides 5-µV offset voltage and 0.2-µV/C offset drift over temperature without the use of internally clocked auto-zero techniques, which increases the accuracy of industrial sensor signal conditioning.
  2. Precise 36-V input range: RRIO enables maximum input dynamic range for precision high-voltage measurement in industrial automation and control applications.
  3. Robust output drive: 60-mA output current drive and 1-nF capacitive-load drive provide system stability for high-voltage buffers and multiplexed data acquisition.

The OPA192 is included in four TI Precision Designs reference design to help engineers quickly evaluate and customise a system:

  1. A 16-bit, 400KSPS, 4-Channel Multiplexed Data Acquisition System for High Voltage Inputs with Lowest Distortion.
  2. A combined Voltage and Current Output Terminal for Analog Outputs (AO) in Industrial Applications.
  3. A Capacitive Load Drive verified reference design using an Isolation Resistor.
  4. A Single Op-Amp Slew Rate Limiter reference design.

A TINA-TI SPICE model is also available with TI Precision Design circuits to accurately simulate and debug the circuit. The OPA192 utilizes a DIP adapter evaluation module or a universal op amp evaluation module to quickly evaluate the functionality and versatility of the device. The OPA192 is also supported by TI's WEBENCH Filter Designer, an online tool that enables engineers to design, optimise, and simulate complete multi-stage active filter solutions within minutes.

The OPA192 is available in three package options for $1.35 (1,000); 5 x 4-mm SO-8; 3