New zero-drift op amp offers high accuracy regardless of temperature changes

ROHM has developed a zero-drift op amp – the LMR1002F-LB. It is created for industrial and consumer electronics devices and minimises input offset voltage and input offset voltage temperature drift. Able to accurately amplify output signals from sensors installed in various measurement devices, this new op amp is excellent for current sensing applications such as power control inverters and temperature/pressures/flow/gas detectors.

As automotive and industrial equipment becomes more sophisticated and application control necessities are more precise, environmental sensors are increasingly being employed to quantify temperature, pressure, and gas concentrations such as carbon dioxide to foster a sustainable society. However, sensor signals are so small that amplification is required, and if a general op amp with 1mV offset voltage is utilised to amplify the sensor signal by a factor of 1,000, for example, the offset voltage also increases by this amount – resulting in a voltage error of 1V (1,000mV) in the signal output. At the same time, input offset voltage temperature drift, which varies according to temperature and time, is difficult to compensate for.

In response, the company developed a zero-drift op amp that meets these problems using proprietary analog circuit technology – cultivated over many years. The device is the company's first zero-drift op amp employing the chopper method. In contrast to conventional low-offset op amps featuring a typical input offset voltage of 150µV (Max.), this new product limits input offset voltage to just 9µV (94% lower). This eradicates the necessity for peripheral components or software to adjust the input offset voltage, reducing design person-hours and costs. On top, input offset voltage temperature drift is just 0.05µV/C (Max.) in the operating temperature range of -40C to +125C – the lowest among the company's op amps. Enabling accurate amplification of measured sensor signals without being affected by environmental changes such as temperature contributes to high accuracy control of industrial equipment in factories. This, together with a wide supply voltage range of 2.7V to 5.5V and rail-to-rail input/output, makes it ideal for various industrial applications.