July17, 2000 - National Semiconductor (NYSE:NSM) today introduced the world's smallest digital temperature sensor - the LM74 in a 1.6 by 1.6 millimeter surface-mount micro SMD package. By virtue of its size, high-precision temperature measurement and low-power operation, the LM74 micro SMD temp sensor is ideal for high-precision temperature measurement in next-generation disk drives, wireless phones, test and measurement equipment, game consoles, or other microprocessor/microcontroller-based applications.
"The LM74 temperature sensor is yet another example of National's leadership in this area," said Jitesh Vadhia, Director of National's Data Conversion Systems group. "It further validates National's position as the industry's leading supplier of digital and analog temperature sensors, as well as a leading innovator in small package design."
The LM74 micro SMD temp sensor features a 12-bit plus sign temperature resolution (0.0625 degrees Centigrade per least significant bit, LSB) and is SPI/MICROWIRE-compatible when operating over a temperature range of -40? C to +125? C. The device operates from a 2.65V to 5.5V supply and typically requires only 265 microamp supply current. In shutdown mode, the serial bus remains active, while current draw lowers to 3 microamps between serial communications.
The chip-scale, leadless micro SMD package is applied to the die entirely at the wafer level using a patented encapsulation process on the front and back of the wafer. With just 0.5 millimeter bump pitch, the micro SMD solder bumps provide the thermal path from the die directly to the printed circuit board. Micro SMD is compatible with standard surface mount chip handling equipment.
The LM74 micro SMD temp sensor consists of a band gap temperature sensing circuit, a gain stage, and a 13-bit delta sigma A/D converter. The simple three-wire SPI/MICROWIRE-compatible interface allows operation as a slave to most popular microcontrollers. National specifically designed the delta sigma A/D converter for DC or very slow signal conversions.
The band gap circuitry acts as a sensor, while the gain stage amplifies the sensor's signal for measurement by the A/D converter. The LM74 micro SMD measures its own die temperature. Temperature data is represented by a 13-bit, two's complement word with an LSB equal to 0.0625?C. The microcontroller can query the LM74 micro SMD at any time to read temperature.
Pricing and Availability
Available now, the LM74 micro SMD temperature sensor is priced at $0.85 in 1000-unit quantities. For more information on the LM74 micro SMD, visit National's World Wide Web site at http://www.national.com/pf/LM/LM74.html, or contact National's Design Support Group at 1-800-272-9959.
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 has about 10,500 employees worldwide. Additional company and product information is available on the World Wide Web www.national.com. To download high resolution photos.
