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National Semiconductorís PWM Controller Utilizes Unique, Low-Noise, Emulated-Current-Mode Architecture for Design Flexibility


LM3495, Ultra-High-Precision, 1.5 MHz PWM Buck Controller, Offers +/- 1 Percent Accuracy in ASIC, FPGA, DSP Designs

July 31, 2006 - National Semiconductor Corporation (NYSE: NSM) today introduced a new pulse-width modulation (PWM) buck controller that employs Nationalís unique emulated-current-mode (ECM) architecture for output voltages with extremely low duty cycles at frequencies up to 1.5 MHz.

The LM3495 powers digital application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), digital signal processors (DSPs) and other embedded processors. Deep sub-micron ICs require tight regulation accuracies in order to perform, and the LM3495 offers industry-leading accuracy of plus or minus 1 percent over a wide temperature range. It has a host of system integration features optimized for these applications. The LM3495 also addresses the additional requirements of point-of-load (POL) module manufacturers with fault-protection features that ensure a reliable end product.

Nationalís new LM3495 expands the companyís power management portfolio, giving designers a choice between Nationalís unique ECM architecture and existing voltage-mode portfolio, the LM274x family. Both architectures allow designers to reach very high operating frequencies and conversion ratios without having to deal with switching noise headaches. National first introduced its ECM architecture with the LM5005 and plans to use it in new products to be introduced throughout the rest of the year, including a dual-output, second-generation, ECM controller designed to optimize performance in the most demanding digital cores.

About the LM3495
In addition to its unique ECM control and highly accurate feedback voltage, the LM3495 includes a host of features that ease the design-in process while also ensuring reliable system performance. The LM3495 has an input voltage from 2.9V to 18V for use in 3.3V, 5.0V, 12V and intermediate-bus systems, as well as an output voltage that is adjustable from 0.6V to 5.5V for existing and future core and I/O voltages. The controller has low-side sensing and a programmable current limit that does not require a sense resistor. This allows for reduced power dissipation, component count and system cost. In addition, the LM3495 has input under-voltage lockout, switch-node short protection, adaptive duty cycle limit and hiccup-mode current limit protection that eliminates thermal runaway during fault conditions. It also has an internal soft start with tracking capability.

The LM3495 has a 200 kHz to 1.5 MHz switching frequency that can be synchronized to reduce radiated system noise. Its on-chip gate drivers are capable of driving FETs suitable for output currents in excess of 20A. The LM3495 has soft shutdown and glitch-free start-up into pre-biased loads to ensure deep sub-micron cores are not damaged. The LM3495, available in a TSSOP-16 package, operates from a single input rail, eliminating the need for an external bias supply.

About Nationalís Power Management Products
National Semiconductor is the number one supplier of voltage regulator ICs with 14 percent market share, according to iSuppliís 2005 Semiconductor Market Share survey. Nationalís 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 also offers online tools that enable power designers to select the best power management chips for their applications. Nationalís Webenchģ design tool allows designers to choose a product, create and analyze a design, and then build custom prototypes that can be delivered within 24 hours. More information about Nationalís power management products is available at

Pricing and Availability
Available now, the LM3495 is priced starting at $3.08 in 1,000-unit quantities. For more information about the LM3495, including how to order samples and evaluation boards, please visit the product folder. To view a high-resolution downloadable photo of this product, visit Nationalís photo gallery.

About National Semiconductor
National Semiconductor, the industryís premier analog company, creates high-value analog devices and subsystems. Nationalís leading-edge products include power management circuits, display drivers, audio and operational amplifiers, interface products and data conversion solutions. Nationalís key analog markets include wireless handsets, displays and a variety of broad electronics markets, including medical, automotive, industrial, and test and measurement applications. Headquartered in Santa Clara, Calif., National reported sales of $2.16 billion for fiscal 2006, which ended May 28, 2006. Additional company and product information is available at

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