National Semiconductor's New Family of Synchronous Controllers Handle the Complex Power Requirements of DSPs, FPGAs and ASICs

"The LM274x family from National Semiconductor is addressing the power requirements of a growing market segment of complex electronics that use DSPs, FPGAs and ASICs, and rely on efficient power management solutions to enable smaller end products," said Paul Greenland, marketing director for National Semiconductor's Power Management group. "This new family of controllers is the next step in National Semiconductor's portfolio of industry-leading power management solutions."

About the LM274x Family

The LM2742, a high-speed, synchronous switching regulator controller, is capable of controlling currents of 0.7 A to 20 A with up to 95 percent conversion efficiency. Power up and down sequencing is achieved with the power-good flag, adjustable soft-start and output enable features. The LM2742 operates from a low-current 5 V bias rail and converts from a 1 V to 16 V power rail. It utilizes a fixed-frequency, voltage-mode pulse width modulation (PWM) control architecture, and its switching frequency can be adjusted from 50 kHz to 2 MHz by setting an external resistor. Current limit is achieved by monitoring the voltage drop across the on-resistance of the conducting low-side MOSFET, with best-in-class 40 ns minimum on-time. The wide range of operating frequencies gives the power supply designer flexibility to fine-tune component size, EMI and efficiency. The adaptive, non-overlapping MOSFET gate drivers and high-side bootstrap driver help maximize efficiency without compromising reliability. This part keeps the low-side MOSFET switched off during shutdown, preventing the discharge of the output filter capacitor.

The LM2743 is a high-speed, N-Channel synchronous buck regulator controller with a 2 percent 0.6V feedback reference voltage. It uses a fixed- frequency, voltage-mode PWM control architecture that is adjustable from 50 kHz to 1 MHz through an external resistor. This wide range of PWM frequencies gives the power supply designer the flexibility to make tradeoffs among component size, EMI and efficiency. The power MOSFETs can run on a separate 1 V to 16 V input voltage rail, while the regulator is biased from a 3 V to 6 V, 2 mA rail. A power-good flag, precision shutdown threshold and soft-start features make power supply tracking and sequencing easy.

The LM2743 also employs current limit, which is achieved by monitoring the voltage drop across the on-resistance of the conducting low-side MOSFET, as well as an output under-voltage and over-voltage flag. The adaptive, non- overlapping MOSFET gate drivers help avoid shoot-through currents while maintaining high efficiency. The high-side and low-side MOSFETs are the N- Channel type, and the IC bootstrap structure enhances the high-side MOSFET for the highest efficiency. The LM2744 has the same feature set as the LM2743 and includes an external reference that the user can connect to an error amplifier for tighter DC output accuracy.

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://www.power.national.com/.

Pricing and Availability

Available today, National's LM2742 is priced at $1.50 each in 1K volumes, the LM2743 is priced at $1.30 each in 1K volumes and the LM2744 is priced at $1.20 each in 1K volumes. All of the products are available in the TSSOP-14 package. More information about the products is available at http://www.national.com/pf/LM/LM2742.html, http://www.national.com/pf/LM/LM2743.html and http://www.national.com/pf/LM/LM2744.html. A high-resolution downloadable photo of the products is available at http://www.national.com/company/pressroom/gallery/power.html.

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/

WEBENCH and National Semiconductor are registered trademarks of National Semiconductor Corporation.

All other brands or product names are trademarks or registered trademarks of their respective holders.

CONTACT: Megan Carter of National Semiconductor, +1-408-721-6929 or
megan.carter@nsc.com

Web site: http://www.national.com/