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Op amp with over-voltage protection for industrial process controls

Munich, Germany – Industrial amplifiers are subject to fault voltages from a variety of sources, including electro-magnetic interference, damaged cabling, lightning strikes and other disturbances on the power grid, incorrect hook-ups to other system components and power-line surges when power to the system is restored after routine service or equipment upgrades. Such over-voltage conditions can cause phase inversion or damage the amplifier and other circuitry, resulting in system lock-up or outright failure. The ADA4091-2 op amp's performance is fully specified, including the device's on-chip over-voltage circuitry. This simplifies equipment design and error analysis and results in more consistent output readings in industrial process controls, battery-powered instrumentation, power supply control and protection systems and remote sensors.

By providing localized signal conditioning and the combination of low offset, low offset drift and wide gain-bandwidth, the op amp delivers precision performance across a variety of sensor inputs, while the over-voltage protection feature prevents phase-inversion errors and excessive input current flows during transient or fault conditions. By integrating the requisite over-voltage protection circuitry, the dual micro-power op amp with rail-to-rail inputs and output allows system designers to reduce the number of external components needed to ensure stable system operation.

The new 1.5-MHz op amp features a low 350-microA-per-channel supply current, a 0.5-V/microsec slew rate, and offset voltage of 500 microV max., which assure system accuracy with varied sensor types in harsh operating environments while eliminating the need for cooling fans or other costly thermal management devices. The 36V op amp protects up to 12V above and below the supply rails at 15V and 25V above and below the supply rails at 5V. The ADA4091-2 is housed in an 8-lead LFCSP. In an industrial signal chain, the device is well matched to operate with a range of ADCs.

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