DIGITAL THERMOMETER FIRST TO INTEGRATE DUAL POWER SUPPLIES AND SOFTWARE-SELECTABLE SPI AND 3-WIRE INTERFACES
DALLAS, TEXAS-November 16, 1999-Dallas Semiconductor today announced the DS1722 Digital Thermometer with SPI/3-Wire Interface, the first digital thermometer to support two separate power supplies and a choice of software-selectable communication interfaces, 3-wire and SPI (Serial Peripheral Interface). By accepting a wide power supply range for analog signals and a very low-power range for digital logic, the DS1722 meets a growing need for multiple-voltage capability in portable, mixed-signal systems. The added choice of standard 3-wire and SPI serial interfaces gives designers the flexibility to match different networking communication protocols in embedded systems.
 Chris Beaudoin, product manager, said, "While high-density logic circuits tend to decrease the size and power needs of handheld instruments, analog signals continue to require higher power levels than digital logic. This means that devices with mixed analog and digital signaling, such as cellular telephones, motor controls, personal computers, and office equipment, operate at higher voltages than strictly digital instruments.
"Any heat-sensitive device that handles both analog and digital signals can benefit from using the DS1722. One pin on the DS1722 accepts an analog power supply over the 2.65-5.5V range, and a separate pin accepts power over the 1.8V-5.5V range. The DS1722 can communicate logic signals with low-voltage processors while handling the higher voltage range among analog components."
The choice of software-selectable SPI and 3-wire interfaces provides flexibility in designing system communications. The SPI data protocol employs a serial bus while supporting the high-speed, high-bandwidth network connections most often used in handheld instruments, particularly cellular telephones and other mobile communication platforms. Alternatively, the 3-wire bus is standard and uses a bi-directional I/O instead of separate data in and out signals. Both interfaces use the same number of pins.
The DS1722's direct-to-digital technology provides temperature readings accurate to ±2.0°C over a range from -40°C to +85°C without additional components. For applications that require greater temperature resolution, the user can adjust the readout resolution from 8 to 12 bits, a useful feature for applications where thermal runaway conditions must be detected quickly.
The DS1722 is ideal for designs in personal computers/servers/workstations, cellular telephones, office equipment, handheld or portable analog instrumentation and process control, or any thermally sensitive system.
The DS1722 Digital Thermometer with SPI/3-Wire Interface is packaged in an 8-pin SOIC and a Flip Chip Package, which reduces package size to that of the chip itself in order to maximize savings in board space and cost. The DS1722 is available from stock and costs $1.00 each in quantities of 1,000.
Dallas Semiconductor manufactures a broad line of mixed-signal, specialty semiconductors. The Company combines proprietary fab and circuit technologies to create innovative products that are sold to over 15,000 customers worldwide. Markets served include broadband telecommunications, wireless handsets, cellular base stations, secure Internet communications, networking, servers, data storage and a wide variety of industrial equipment.
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