Tiny Buck Converters Feature Dynamic-Gain Architecture for Up to 90 Percent Efficiency in an Inductor-Free Footprint
The LM2770, LM2788, LM2797 and LM2798 DC-DC converters feature output currents up to 250 mA over the extended Li-Ion battery range of 2.7 V to 5.5 V. The unique dynamic-gain architecture provides efficiency up to 90 percent, which is comparable to traditional buck regulator solutions that require external inductors. A choice of two tiny packages along with four small ceramic capacitors and no external inductor provides the engineer with an extremely compact footprint that minimizes board space and optimizes the bill of materials. The LM2770 also features user-selectable output voltages for increased flexibility of design and a low-power, low-dropout sleep mode that reduces the quiescent current and dramatically improves standby times. The LM2797 and LM2798 feature input and output voltage monitoring that prevents unexpected power loss and instability issues during operation.
"Top mobile phone manufacturers rely on National Semiconductor to provide solutions that deliver the ideal combination of efficiency and size," said Peter Henry, vice president of National Semiconductor's Portable Power Products Group. "National's new DC-DC converters maximize performance and minimize the solution footprint to offer unparalleled portable power solutions."
Key Technical Specifications of National's New Step-Down Converters
The LM2770 is a regulated switched capacitor step-down DC-DC converter with an output current capability of 250 mA over an input range of 2.7 V to 5.5 V. It is available in fixed output voltage options of 1.2 V, 1.5 V and 1.6 V. The LM2770 has a low-power sleep mode that limits the quiescent current to 30 uA and significantly extends standby times. Pin-selectable output voltages provide flexibility for system design. The LM2770 is available in a miniature 10-pin, non-pullback LLP(R) package.
The LM2788 is a regulated switched capacitor step-down DC-DC converter with an output current capability of 120 mA over an input voltage range of 2.6 V to 5.5 V. The LM2788 is available in fixed output voltage options of 1.5 V, 1.8 V and 2.0 V. The device utilizes multiple fractional voltage-gain steps to maximize power efficiency over the entire input voltage and output current ranges. The low supply current of 32 uA further contributes to long standby operation.
The LM2788 is available for simulation on National Semiconductor's award winning WEBENCH tool at http://www.national.com/cgi-bin/WebenchTemplate?base_pn=LM2788 .
The LM2797 and LM2798, with the same features as the LM2788, also include input and output voltage-monitoring characteristics. One signal monitors the battery and indicates when the input voltage falls below 2.85 V while another pin verifies that the output voltage is no more than 5 percent below the nominal output voltage of the part. The LM2797 has a faster turn-on time of 100 us. Each is packaged in a small MSOP-10.
About National's Power Management Products
National Semiconductor is the number one supplier of power management ICs with 12.8 percent market share, according to iSuppli's 2004 voltage regulator/reference survey. National's power management revenue grew 29.7 percent in 2003 over the previous year, compared to 17.3 percent growth for the industry during the same time period. National's innovative power management products include best-in-class linear regulators; power monitoring, control and reference ICs; and switching converters, such as high-voltage ICs for DC/DC conversion, switched capacitor converters, lighting management ICs and inductive switching converters. National's WEBENCH(R) online design tool allows designers to select a power management product, create and analyze a design, and then build custom prototypes that can be delivered within 24 hours. More information about National's power management products is available at http://power.national.com/ .
Pricing and Availability
Available now and priced in 1,000-unit quantities, the LM2770 is $1.40, the LM2788 is $1.00, and the LM2797 and LM2798 are each $1.10.
More information about the products is available at http://www.national.com/pf/LM/LM2770.html , http://www.national.com/pf/LM/LM2788.html , http://www.national.com/pf/LM/LM2797.html and http://www.national.com/pf/LM/LM2798.html . For more information on National's power management products, visit http://power.national.com/ .
About National Semiconductor
National Semiconductor, the industry's premier analog company, creates high-performance analog devices and subsystems. National's leading-edge products include power management circuits, display drivers, audio and operational amplifiers, communication interface products and data conversion solutions. National's key markets include wireless handsets, displays, PCs and laptops. The company's analog products are also optimized for numerous applications in a variety of electronics markets, including medical, automotive, industrial and test and measurement. Headquartered in Santa Clara, California, National reported sales of $1.98 billion for fiscal 2004, which ended May 30, 2004. Additional company and product information is available at http://www.national.com/.
NOTE: National Semiconductor, LLP and WEBENCH are registered trademarks of National Semiconductor Corporation.
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