Zero drift op amp for current measurement
Rohm has developed a zero-drift operational amplifier (op amp) for industrial and consumer power designs.
Rohm used an analog chopper design technique for the first time in the LMR1002F-LB to minimize both the input offset voltage and input offset voltage temperature drift for current sensing applications such as power control inverters and temperature/pressures/flow/gas detectors.
If a general op amp with 1mV offset voltage is used 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
The zero-drift op amp is the first Rohm op amp to use a chopper approach. This limits the input offset voltage to just 9µV, 94% lower than the typical offset voltage of 150 µV. This eliminates the need for peripheral components or software to adjust the input offset voltage, reducing the design complexity and costs.
At the same time the input offset voltage temperature drift is just 0.05µV/°C (Max.) in the operating temperature range of -40°C to +125°C – the lowest among Rohm’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, coupled with a wide supply voltage range of 2.7V to 5.5V and rail-to-rail input/output, make it ideal for a variety of industrial applications.
The next step is to reduce the noise and offset while increasing power savings and expanding the power supply voltage range demanded in the automotive and industrial equipment markets.
The zero drift op amp is available through DigiKey and Mouser and at other online distributors as it becomes available.
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