Linear Technology's LT6375 is a unity-gain difference amplifier with integrated precision matched resistor, which precisely levels shifts and buffers small difference signals, while rejecting up to ±270 V common mode. The A-grade version achieves CMRR of 97 dB (minimum), initial gain error of 35 ppm (maximum), gain drift of 1 ppm/°C (maximum), and gain nonlinearity of 2 ppm (maximum) with a common mode divide ratio of 25:1. The common mode divide ratio is selectable from 7:1 to 25:1, enabling the designer to select the ratio with the best performance for a given common mode input range. At the heart of the LT6375 is a high-precision over-the-top amplifier which operates with inputs both within and above the 3.3 V to 50 V supply voltage. This permits the combination of a wide input range and low-voltage supply. Use of a low-voltage supply limits power consumption and protects downstream circuitry from high voltage. It offers seven different divider ratios for optimization of precision, noise, and speed for specific input range requirements.

The LT6375 includes many other useful features, including rail-to-rail outputs, low supply current, and a shutdown mode. It is available in a 4 mm x 4 mm DFN and a 4 mm long MSOP package, both with 12 leads. including skipped leads for extra spacing of high voltage input signals. The LT6375 is fully specified over the -40°C to 85°C (I-grade) and -40°C to 125°C (H-grade) temperature ranges.

Video: Wide Common Mode Range Current Sensing