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TI Unveils Industry's Lowest Power Zero-Drift Amplifiers for Precision Signal Conditioning

The manufacturer says . . .

ChipCenter's Paul O'Shea says . . .

Texas Instruments announced the industry's lowest power zero-drift operational amplifiers from the company's Burr-Brown product line which are ideal for precision, power-sensitive applications such as handheld test equipment, medical instrumentation, temperature measurement, transducer signal amplification, electronic scales, automotive systems and battery-powered instruments. "The OPA334 and OPA335 provide customers with the ultimate cost-effective solution for precision signal conditioning and reinforce TI's leadership position in the low-power, low-voltage market," said Tadija Janjic, strategic marketing engineer of TI's high-performance amplifier products. "By offering a 3x reduction in quiescent current, these devices enable customers to achieve higher precision designs while reducing power consumption." The OPA334 and OPA335 op amps are available in micro-size SOT23 packages and feature low quiescent current (300uA), single supply operation and rail-to-rail output swing within 10mV of the rails. The devices use auto-zeroing techniques to provide ultra low offset voltage (1uV typical) and near zero drift over time and temperature (0.02uV/C). The OPA334 family includes a shutdown mode allowing the OPA334 to be switched from normal operation to a standby current that is less than 1uA. The OPA334 and OPA335 operate on single or dual supplies as low as +2.7V (+/-1.35V) and up to +5.5V (+/-2.75V). All versions are specified from -40C to +125C. The OPA334 (single version with shutdown) comes in a SOT23-6. The OPA335 (single without shutdown) is packaged in a SOT23-5 and SO-8. The OPA2334 (dual with shutdown) comes in an MSOP-10. The OPA2335 (dual without shutdown) is available in an MSOP-8 and SO-8. Texas Instruments Incorporated, Semiconductor Group, SC-02109, Literature Response Center, P.O. Box 954, Santa Clara, CA 91380, Tel: 1-800-477-8924, ext. 4500. Website: www.ti.com

These parts herald the entrance of TI to the modern operational amplifier market, something even the company admits was long overdue. One might not fault them for taking their time in this very crowded space with top notch competitors like Linear Technology, Analog Devices, Maxim and National Semiconductor. TI kept looking for the angle where they could not only make a me-too part but also one that would capture the interest of analog designers. They decided on an op amp with extremely low quiescent current because several customers indicated they needed one. As you can see from the specs, TI has an extremely low quiescent current, purportedly 3x lower than any competitor on the market. The company says they did this without sacrificing noise or any other spec that goes hand-in-hand with quiescent current. You might wonder how they accomplished the low quiescent current. The company says they looked for design errors that affect quiescent current ý and one of them was the oscillator. TI brought to bear all their previous knowledge of design to get the right oscillator design and other parts, to lower the quiescent current. They knew that a major portion of the current was in the conventional amplifier. For example, an auto-zero amplifier works by using a conventional amplifier that is zeroed by another amplifier. They used that design but the company drew on their design knowledge to keep the power ratio low for the amplifier and used two of those in connection with an efficient oscillator. This op amp raises the bar because you get low drift, low offset, and now low quiescent current. This is important for designers that need low power in addition to high performance (low drift over time and temperature). For example, TI had some customers developing sensors for gas pipelines. The sun and batteries power the sensors. The lifetime of the device is very important because if the battery dies the company has to go into areas with extremely cold temperatures. More typical applications include precision sensors, weight sensors, and strain gauges. To meet the requirements of some of these applications TI needed to specify them for temperatures from ý40 to +125C, which makes it compatible for automotive electronic designers. The +125C spec compares favorably to other op amps on the market that are specified to only +85C. The company says the OPA335 has already been designed into some automotive designs to condition signals coming out of brake sensors. To make this device more accessible to a wider range of designers TI decided to offer it with a shutdown mode (the OPA334, SOT23-5 packaging) as well as without a shutdown mode (the OPA335, SOT23-6 packaging). So you can design for a SOT23 pkg. and later select the ý5 or ý6 features. There are many applications for this product including medical instrumentations, test and measurement, weight scales, and automotive designs. TI expects that the majority of the applications will be in automotive applications. TI says it can also be used in optical networking as a companion part to the LOG100 series and as a companion part in the TI transimpedance amplifier design. The OPA334 and OPA335 are priced from $0.95 in 1,000 piece quantities (suggested resale price). The OPA2334 and OPA2335 are priced from $1.50 in 1,000 piece quantities (suggested resale pricing). Product brochure: http://www.ti.com/rd/sc02109 .

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