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Small op amps have 5-16V operating range

Posted: 28 Jun 2007 ?? ?Print Version ?Bookmark and Share

Keywords:precision op amps? zero-drift op amps? power efficiency?

Op amps from ADI

Analog Devices Inc.'s AD8663 and AD8638 precision operational amplifiers deliver a combination of high accuracy, power efficiency and versatility with a wide 5-16V operating range for an assortment of industrial, medical and consumer applications.

Manufactured on ADI's proprietary iCMOS high-voltage process technology, the precision op amps are in packages that are 70 percent smaller than competing devices, making them suited for high-density and portable applications where board space is a premium.

Rail-to-rail op amp
AD8663 is a 16V precision, low noise, rail-to-rail op amp that addresses the performance, power and cost requirements of portable and battery-operated applications, such as patient monitors, defibrillators, remote industrial controls and optical sensors. These types of higher-voltage portable devices are increasingly adopting Li-ion, lithium-polymer and other batteries operating at 3-16V ranges. This shift in battery technologies is creating a growing demand for signal conditioning components capable of supporting high voltages, while also providing excellent power efficiency, thermal management and precision.

AD8663 incorporates ADI's patented DigiTrim in-circuit trimming technology to achieve low offset voltage, 90dB common mode rejection ratio and 105dB power supply rejection ratio, thus providing 90 percent better accuracy than other similar devices. The device also features high performance over varying power supplies and temperatures, with a maximum voltage offset drift of 450?V at 125C over a wide input range. AD8663 consumes only 180?A while keeping low-frequency voltage noise at 21nV/rt-Hz.

AD8663's combination of high precision, low power consumption, small size and stability over temperature makes it suitable for pressure, temperature and fiber-optic sensors, portable industrial tools and other applications where accuracy must be maintained over fluctuating environmental conditions. Zero-drift op amp
AD8638 is a 16V zero-drift precision op amp designed for industrial instrumentation, automotive and sensor applications that must accommodate wide variations in temperature, power supply, load and input signal without introducing signal conditioning errors. The op amp extends the operating voltage and temperature range for both single- and dual-supply applications and is claimed to be the first to combine the size, power and performance advantages of the iCMOS industrial manufacturing process with ADI's patented auto-zero and low-drift technologies. The result is a device with 140dB CMRR and 140dB PSRR, making it up to 10dB more accurate than competitive zero-drift op amps.

For designers requiring high precision temperature-, current- or pressure measurement in systems using thermocouples, strain gauges and position sensors, AD8638 features a 10?V offset voltage over temperature and a maximum offset drift of 80nV/C, alleviating the need for additional circuitry such as temperature correction loops. Applications include sensors in harsh or ruggedized environments or temperature-sensitive feedback and control circuits that are designed to take frequent, measurements where the outputs are driven into the supply rails.

The AD8663 precision op amp and a dual-channel version, AD8667, are sampling now and will be available in full production quantities in July. AD8663 is housed in an 8-lead LFCSP (3-by-3mm, lead-frame chip-scale package) for 64 cents each or an 8-pin SOIC package for 60 cents each, both in 1,000-piece quantities.

AD8667, housed in an 8-pin MSOP, is priced at 80 cents each while the version available in 8-pin SOIC costs 78 cents each, both in 1,000-piece quantities. AD8638 is sampling now and will be available in full production quantities in September. The AD8638 ships in a SOT-23 package and is priced at $1.20 per unit in 1,000-piece quantities.

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