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National Semiconductor Introduces Industryís First 100V Current-Mode Buck Controller


APEC, ANAHEIM, CALIF. - February 26, 2007 - Worldwide power management leader National Semiconductor Corporation (NYSE:NSM) today introduced the LM5116, the industryís first 6V to 100V current-mode buck controller for use in telecommunications, automotive and industrial control applications. The LM5116 features a unique combination of high performance, flexibility and ease-of-use for DC-DC power supply designs. The device joins Nationalís portfolio of synchronous buck controllers, offering extended input voltage range and load current capability.

National is demonstrating the LM5116 in booth 819/821 at the Applied Power Electronics Conference and Expo (APEC) in Anaheim, California. The exhibit is open through March 1 at the Disneyland Hotel. For more information on Nationalís products and speakers at APEC, please visit Nationalís events page at

The LM5116 is well-suited for step-down regulator applications from a high voltage or widely varying input supply. The current mode control utilizing Nationalís patented emulated current-mode (ECM) technology reduces noise sensitivity of the pulse-width modulation (PWM) circuit. It enables reliable control of very small duty cycles necessary in high input voltage applications. Additional features include thermal shutdown, programmable soft-start, frequency synchronization, cycle-by-cycle current limit and adjustable line under voltage lockout (UVLO).

About Emulated Current-Mode Technology
Emulated current-mode control overcomes the noise susceptibility and duty cycle limitations of traditional peak current-mode control by emulating the buck switch current signal, which is used for pulse-width modulation. The emulated current signal is developed by charging a capacitor with controlled currents that produce a capacitor voltage waveform directly proportional to the current in the buck switch. Developing the current signal for the PWM without directly measuring the buck switch current minimizes the effect of switching noise, while maintaining the benefits of the current-mode control.

Technical Features of the LM5116 Buck Controller
The LM5116 has an ultra-wide input range up to 100V, with a programmable output range from 1.215V to 80V. The reduced noise sensitivity of the PWM control circuit allows reliable operation with very small duty cycles necessary in high input voltage applications. The emulated current ramp enables the LM5116 to exceed a 20:1 Vin:Vout step-down ratio when operating at 500 kHz. The operating frequency is user-programmable up to 1 MHz with the capability to synchronize switching to an external clock signal. A low quiescent-current sleep mode disables the controller and consumes only 10 microamps of total input current for minimal off-state drain in battery-powered applications. A user-selectable diode emulation mode enables discontinuous inductor current operation at light load conditions for improved efficiency. Controlled start up into a pre-biased load is achieved by gradually disabling the diode emulation of the synchronous MOSFET. The programmable soft-start, input UVLO and voltage tracking features further enhance the system designerís control of the turn-on transition.

The LM5116 is available in a power-enhanced TSSOP-20 package featuring an exposed die attach pad to aid thermal dissipation.

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 WEBENCH 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 LM5116 is priced at $3.25 in 1,000-unit quantities. For more information about the LM5116, including how to order evaluation boards and samples, please visit
Note to Editors: To view high-resolution downloadable photos of these products, visit Nationalís photo gallery at


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