National Semiconductor’s Tiny 2 MHz, 600 mA DC-DC Converter Maximizes Battery Life in Portable Devices

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Gayle Bullock
National Semiconductor
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gayle.bullock@nsc.com

National Semiconductor’s Tiny 2 MHz, 600 mA DC-DC Converter Maximizes Battery Life in Portable Devices

Highly Efficient Step-down Converter Features Low Ripple, Low Noise

January 25, 2006 - National Semiconductor Corporation (NYSE:NSM) today introduced a 2 MHz, pulse-width modulation (PWM), 600 mA step-down DC-DC converter in a very small package.  The LM3674 is well-suited for handheld devices such as mobile phones, PDAs, MP3 players, portable instruments, W-LAN, digital still cameras and portable hard disk drives.

The LM3674 step-down DC-DC converter is optimized for powering low voltage circuits from a single Li-Ion cell battery and input voltage rails from 2.7V to 5.5V.  It provides up to a 600 mA load current over the entire input voltage range.  During PWM operation, the device operates in a low-noise fixed frequency mode with a peak-to-peak output voltage ripple of less than 5 mV.  Internal synchronous rectification provides high efficiency during PWM operation.  In shutdown, the device turns off and reduces battery consumption to 0.01 µA (typ).

The LM3674 is packaged in a SOT23-5.  Lead-free package options are also available. A high switching frequency of 2 MHz (typ) allows use of only a 2.2 uH inductor and two tiny ceramic capacitors.

Key features for the LM3674 include:

• 600 mA max load current 
• Input voltage range from 2.7V to 5.5V 
• Output voltages range from 1.0V to 3.3V 
• Operates from a single Li-Ion cell battery 
• Internal synchronous rectification for high efficiency 
• Internal soft start 
• 0.01 µA typical shutdown current 
• 2 MHz PWM fixed switching frequency (typ) 
• Current overload protection and thermal shutdown protection

About National’s Power Management Products
National Semiconductor is the number one supplier of power management ICs with 14.1 percent market share, according to iSuppli’s 2005 voltage regulator/reference survey.  National’s power management revenue grew 37.3 percent in 2004 over the previous year, compared to 24 percent growth for the industry.  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 also offers online tools that enable power designers to select the best power management chips for their applications.  National's 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.

Pricing and Availability
National’s LM3674 is available now and costs $1.46 in quantities of 1,000. 

For more information about the LM3674 or to order samples, visit http://www.national.com/pf/LM/LM3674.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-value 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 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, California, National reported sales of $1.91 billion for fiscal 2005, which ended May 29, 2005.  Additional company and product information is available at www.national.com.

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