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NATIONAL SEMICONDUCTOR'S LM83 TEMPERATURE SENSOR MEASURES TEMPERATURES AT FOUR POINTS

LM83 is compatible with both SMBus and I2C interfaces

Dec 7, 1999

December 7, 1999 - National Semiconductor Corporation (NYSE:NSM) today announced the LM83, a versatile, highly accurate digital temperature sensor that measures temperatures at four points in a system, three external to the device plus the internal temperature of the device itself. In the past, only the CPU's temperature needed to be monitored. In today's systems, other components such as the battery, graphics accelerator, and PCMCIA card cages require temperature monitoring as well.

The LM83 has two programmable temperature-interrupt outputs. The interrupts are triggered when any of the monitored temperatures exceeds a programmable level. By programming them for different temperatures, they could be used, for example, to first signal a rising temperature and then signal that the temperature has exceeded a critical level. Because the LM83 uses delta-sigma analog-to-digital conversion to measure temperature, it exhibits inherently excellent noise rejection, an important specification for a remote-sensing device. The LM83 is compatible with both I2C and SMBus interfaces. To enhance the reliability of the system being monitored, the device has SMBus timeout.

"The LM83 is targeted at applications requiring sophisticated temperature control such as PC notebooks, desktops, workstations, and servers as well as electronic test equipment and office electronics," said Zaryab Hamavand, temperature sensor product marketing manager at National. "The LM83 measures temperatures remotely with either diode-connected 2N3904s or diodes within other devices such as those in Pentium II processors."

Local temperature accuracy measures ?1.0 ?C (typical) while remote-diode temperature accuracy is ?3 ?C (max) from +25 ?C to +100 ?C and ?4 ?C (max) from 0 ?C to +125 ?C. Three-state logic inputs allow two pins to select up to nine SMBus address locations for the LM83. The device's supply voltage can range from 3.0 V to 3.6 V and supply current is 0.8 mA (max).

Pricing and Availability
Available now, the LM83 costs $2.60 each in 1000 unit quantities and is packaged in a 16-pin QSOP. For more information, please visit www.national.com/pf/lm/lm83.html.

About National Semiconductor
National Semiconductor provides system-on-a-chip solutions for the information age. Combining real-world analog and state-of the-art digital technology, the company's chips lead many sectors of the personal computer, communications, and consumer markets. With headquarters in Santa Clara, California, National reported sales of $2 billion for its last fiscal year and currently has about 11,000 employees worldwide. Additional company and product information is available on the World Wide Web at www.national.com.