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National Semiconductor Continues Industry Leadership Role in Power Management with New Series of LDOs

Nov 6, 2001

November 6, 2001 - National Semiconductor Corporation (NYSE:NSM) today announced the addition of the LP398x series of CMOS low-dropout linear voltage regulators (LDOs) to its portfolio of products for use in mobile phones, PDAs, palmtop PCs and other battery-powered electronic devices.

Based on the "best-in-class" features of the LP3985, announced last November, the LP398x series is next generation technology following up National's often-imitated LP298x series of bipolar LDOs. National set the standard with the LP2980 - selling more than 1.3 billion LP298x series LDOs worldwide.

"National Semiconductor is already a leading supplier of analog and mixed-signal ICs to the major players in the portable electronics market," said John Guyatt, National's worldwide marketing manager for power management system-on-a-chip devices and linear voltage regulators. "The LP398x series adds another seven LDOs to the power management portion of National's complete portfolio that also includes audio, wireless, temperature sensor, and amplifier products, among others, all optimized for use in portable applications."

Most of the integrated circuits (ICs) found inside handheld electronic devices operate from lower voltages than those supplied by today's most popular battery technologies. LDOs bridge the gap by stepping the battery voltage down to the levels required to power microprocessors, wireless transmitters and receivers, audio circuits and other systems.

Designers of portable products value the dropout performance of voltage regulators because it directly affects how long consumers can use their products before the batteries must be recharged. It affects key selling points such as talk time, web browsing time and price.

Dropout performance is where CMOS exceeds the performance of bipolar LDOs. The LP3985, for example, features just 100mV maximum dropout at 150mA load, five to six times lower dropout than bipolar LDOs suitable for the same applications. In addition, when compared to other CMOS LDOs, the LP398x series devices' dropout performance continues to lead the market.  LP398x series LDOs are built on a half-micron pure CMOS process usually used to build large digital chips. Using process features originally intended to ease the routing of digital signals and increase gate density, National's analog IC designers created LDOs with the lowest dropouts available on the market today, on the order of two to three times lower than competing CMOS LDOs.

Closely linked to an LDO's dropout performance is its ability to shield its loads from system noise while it operates near dropout. As the battery discharges, moving a typical LDO closer and closer to dropout, the LDO's power supply rejection ratio (PSRR) degrades. LP398x series LDOs use an innovative new architecture to achieve high PSRRs even near dropout. The LP3985, for example, achieves the same PSRR with just 200mV headroom (battery nearly empty) that competing devices only achieve with 1V headroom (battery full).

LP398x series LDOs are capable of supplying loads up to 300mA at output voltages ranging from 1.3V to 5.5V.  Each regulator features ultra-low dropout, excellent PSRR, low noise, fast turn-on time, low quiescent current and stability using low value, low-cost chip capacitors (tantalum for the LP3984, ceramic for all others). Particularly well suited for application in handheld, battery-powered equipment, the LP398x CMOS LDO series also features thermal shutdown protection with short-circuit current limiting.

Members of the LP398x LDO series are offered in a variety of chip-scale packages including National's revolutionary micro SMD and leadless leadframe (LLP) packages. In the case of micro SMD, a package National pioneered, the silicon die is the package. This feature gives micro SMD several advantages over traditional plastic leaded packages including reductions in footprint areas on the order of three to nine times, higher I/O density, and better electrical performance. Depending on the particular LDO, LP398x series LDOs are available in 4-, 5-, and 8-I/O micro SMD packages. National's LLP packages feature industry-leading thermal capability in dramatically smaller, thinner form factors than traditional power packages. Most LP398x series devices are also offered in traditional plastic leaded packages as well.

Each series member is optimized to meet specific design and development specifications.

  • The LP3981 is a 300mA LDO available in the MSOP-8 package now and the LLP-6 package soon. It's ultra-low dropout, high PSRR and low noise make the LP3981 an ideal solution for supplying high-current analog loads such as the speakerphone audio amplifiers found in mobile phones.      
  • The LP3982 is a 300mA LDO with specifications similar to those of the LP3981. In addition, the LP3982 features an adjustable output voltage and a fault flag. The LP3982 is available in the MSOP-8 package.      
  • The LP3984, available in the sub-miniature micro SMD-4 package, is the world's tiniest LDO. The LP3984 is a cost-effective supply for low-voltage digital loads up to 150mA. It is also available in the SOT23-5 package.      
  • The LP3985 is a 150mA LDO available in the micro SMD-5 and SOT23-5 packages. It features ultra-low dropout, high near-dropout PSRR and low noise making the LP3985 an ideal supply for noise sensitive RF and analog circuits.      
  • The LP3986 is a dual 150mA LDO. Essentially a dual LP3985, the LP3986 is ideal for supplying co-located RF and analog loads such as the TX/RX circuits in mobile phones and wireless PDAs. It's available in the micro SMD-8 package giving the LP3986 the distinction of being the world's tiniest dual LDO. Micro SMD packaging enables miniaturization without performance sacrifices.      
  • The LP3987 is a 150mA LDO featuring an innovative sleep mode for increasing the standby times of portable equipment. It is available in the micro SMD-5 package.      
  • The LP3988 is a 150mA LDO featuring a power-good flag available in a SOT23-5 package.

Pricing and Availability
The LP3981, LP3985, LP3986 and LP3988 are available now. The LP3982, LP3984 and LP3987 will be available soon. The single LDOs are priced in the range $0.35 to $0.52 depending on the particular device. The LP3986 is priced at $0.78. All prices are for a quantity of 1000 units.

For information on the LP398x family, visit www.national.com/cmosldo.  To view a high-resolution downloadable photo of visit National's photo gallery at http://www.national.com/company/pressroom/gallery/power.html.

About National Semiconductor
National Semiconductor is the premier analog company driving the information age. Combining real-world analog and state-of-the-art digital technology, the company is focused on the fast growing markets for wireless handsets; information appliances; information infrastructure; and display, imaging and human interface technologies. With headquarters in Santa Clara, California, National reported sales of $2.1 billion for fiscal year 2001 and employs about 9,700 people worldwide.  Additional company and product information is available on the World Wide Web at www.national.com