National Semiconductor Unveils Industry’s Smallest One-Amp Voltage Regulators

January 15, 1998 -- National Semiconductor Corporation® today announced the smallest high-current regulators in the 1A market - the LM317 adjustable positive regulator, the LM337 adjustable negative regulator, and the LM340, a fixed 5V version. The new devices are the first of their kind to be offered in a true surface-mount SOT-223 power package. Although pin-compatible with the D-Pak (TO-252), the SOT-223 occupies 30% less printed circuit-board space. Moreover, it occupies 80% less space than the standard TO-220 package. With an all-copper leadframe replacing less effective alloy, National’s SOT-223 package achieves a junction-to-case thermal impedance rating of 51 degrees C per watt.

"The real value of this packaging breakthrough is space conservation where micro-miniaturization is paramount," said Seamus Coyle, National's strategic technical marketing manager. "Thanks to its ease of assembly and power handling capability, the SOT-223 package is now the popular choice for space-constrained applications. As supply voltages continue to drop, the demand for systems in smaller and lighter packages will continue to rise,"he added.

The new LM317 power regulator delivers a guaranteed 2% output voltage tolerance and is adjustable down to 1.2V.

The LM337 is an adjustable negative 1A regulator with an output voltage range of -1.2V to -37V.

The LM340 5V positive 1A regulator has an output voltage tolerance of + or -4% at 25 degrees C. The new regulators’ specifications in the SOT223 package are the same as their predecessors. Like the TO-220 versions, line regulation of all three devices is 0.01%/V (typical) with a load regulation of 0.3%. Also, all three offer full overload protection, current limit, thermal overload protection and safe area protection.

Price and Availability
The LM317EMP, in National's SOT-223 three-pin package, is priced at $.41 each when purchased in quantities of 1000. The LM337IMP is priced at $.44 in 1000s, while the LM340MP-5.0, also in the SOT223-3 package, is similarly priced at $.33.

National Semiconductor Corporation, a Fortune 500 company, produces system-on-a-chip silicon solutions for the information highway, based on its leadership in analog and mixed signal technologies. National is headquartered in Santa Clara, California, and focuses on the communications, personal systems and consumer markets. National has annual sales of approximately $2.5 billion and 13,000 employees worldwide. Additional company and product information is available on the World Wide Web at www.national.com.