ADI’s video amps conserve battery power

Norwood, Mass. — Today Analog Devices, Inc. introduced a pair of high-performance video amplifiers that offer low operating power and what it claims is the industry's lowest standby power — enabling longer battery life in portable multimedia consumer applications, such as MP3 players and digital video cameras.

The new family of low-power amplifiers, including the single ADA4850-1 and dual ADA4850-2, are designed for battery-powered video devices to efficiently playback high-quality video on televisions. When video display is not needed, the amplifiers have a patent-pending low-power standby mechanism that significantly reduces power consumption — consuming as little as one-tenth the power of the closest comparable devices.

Priced to save as much as 50 percent compared to bipolar and CMOS amplifiers that have higher standby power, these amplifiers save space and component costs by integrating the low-power standby feature in a tiny 3 x 3-mm CSP.

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ADI's Competitive Analysis Graph

Note: ADI has included devices manufactured by Linear Technology Corp. (LT6230 and LT1812), National Semiconductor Corp. (LMH664X), and Intersil Corp. (EL51XX and EL2176), in the competitive overview above because these devices fit the bill in regard to the competitive minimum requirements that are spelled out on the slide. The EL2176 came out in 1995, while the LMH664X family and LT1812 were released in 2002 and 2001, respectively.

“Our new video amplifiers allow designers to easily meet the lowest possible power levels demanded by battery-operated applications without the usual tradeoffs in image quality, or the space and price premiums associated with traditional discrete solutions,” said Bob Esdale, product line director for the high-speed linear group at Analog Devices.

The ADA4850 low-power video amplifiers minimize operating current to 2.7 milliamps maximum and have the industry's lowest standby current at less than 1 microamp, according to ADI. This energy consumption breakthrough is achieved using a patent-pending internal shut down mechanism. The devices also include rail-to-rail outputs that allow driving line-terminated video lines on single-supply voltages as low as 2.7 volts.

The amplifiers have excellent differential gain and phase of 0.04 percent and 0.06 degrees, respectively. Combined with ADI's ADV7179 chip-scale video encoder, the ADA4850 enables one of the most power efficient portable television-output solutions available today.

The ADA4850 video amplifiers are available in full production quantities. Both single and dual output devices are offered in a 3 x 3-mm LFCSP. The single ADA4850-1 is priced at 55 cents per unit, and the dual ADA4850-2 is priced at 69 cents per unit in 1,000-piece quantities.

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These video amplifiers from Analog Devices will enable you to connect small portable consumer devices like cell phones, MP3 players, portable AV players, digital still cameras (DSC), digital video cameras, and PDAs to your television sets. This way, you can play video games from your cell phone on your big screen TV, and show off photos from your DSCs and cell phones on your TVs at your next family gathering. The application possibilities are endless, according to Max Liberman, product manager for ADI's high-speed amp group.

The key features of these video operational amplifiers are low stand-by current (drawing less than 1 microamp maximum), low operating current or quiescent current (2.5 milliamps), low supply voltage (2.7- to 5 volts), and rail-to-rail output. Additionally, power management circuitry has been integrated within the amplifiers.

There is a huge demand for longer battery life in portable consumer electronics, which ADI believes it has addressed with these devices, Liberman said. One way to sustain battery life is to minimize battery drainage while in stand-by mode.

Even though ADI scaled back power consumption (2.5 milliamps), the company felt it was important to maintain excellent quality images.

There are three specifications that cover video distortion: — 0.1 dB flatness (14 MHz), differential gain (0.04%), and differential phase (0.06 degrees). The lower these numbers are, the better quality video you will get. “Typically, you will only see 1 percent for differential gain and 1 degree for differential phase in consumer applications,” Liberman said.

Rail- to-rail output is another key feature of the ADA4850. Video typically requires a 2-volt signal when it's line terminated. So, if it doesn't have rail-to-rail output, you might have up to 1 volt on either side of the supply rails. “Rail-to-rail output provides enough dynamic range in video applications to get the whole 2 volts when operating on low supply voltages,” Liberman said.

ADI also boosted the operating temperature of the ADA4850 in order to improve reliability and extend the device's usability into industrial applications. The operating temperature for consumer applications is generally around 85°C, while ADI's ADA4850 operational amplifier provides an operating temperature of 125°C.

The ADA4850 single and dual version video amps are the first products in a new family. Previously, ADI's AD8063 family, which is about two years old, provided similar benefits as far as video performance specifications, but not with such a low power down mode. “I believe there is a difference of about 400 microamps if you look at this device, compared to the AD8063, in terms of how much better it performs when its disabled,” said Roxie Paine, ADI's product marketing engineer for high-speed amps.

ADI was able to achieve these results using their proprietary process called extra fast complimentary bipolar (XFCB), Paine said. Although the process has been around, the new design for the ultra low power down mode is patent pending. “The design is about minimizing the current in the bias block when the amplifier is disabled,” Paine explained.

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Block Diagram of ADI's ADA4850 Video Amp”

Customers are getting a lot more bang for their buck with these new devices that cost less than the old ones but offer so much more. The AD8063 is priced at 85 cents for a single version, compared to the new ADA4850 video amplifiers, which cost 55 cents for a single and 69 cents for a dual version, in 1,000-piece quantities.

ADI leads the pack in the high-speed operational amplifier market, followed by Intersil and Texas Instruments Inc., according to Databeans Inc. (Reno, Nev.) High-speed amplifiers, including video amps, are growing faster than the overall op amp market, at 14 percent compound annual growth rate (CAGR), versus 9 percent, over the next five years.

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