DS1722 Digital Thermometer with SPI/3-Wire Interface www.maxim-ic.com FEATURES PIN ASSIGNMENT Temperature Measurements Require No V 1 8 V DDD DDA External Components 1 8 * V V DDA DDD CE 7 2 SERMODE 2 7 SERMODE Measures Temperatures from -55C to CE SCLK 6 3 SDI 3 6 SDI SCLK +120C. Fahrenheit Equivalent is -67F to 4 5 SDO GND 4 5 SDO GND +248F Thermometer Accuracy is 2.0C DS1722S DS1722U 8-Pin SO (150mil) 8-PIN MAX Thermometer Resolution is Configurable from 8 to 12 bits (1.0C to 0.0625C PIN DESCRIPTION Resolution) SERMODE - Serial Interface Mode Data is Read From/Written to Via a Motorola CE - Chip Enable Serial Peripheral Interface (SPI) or Standard SCLK - Serial Clock 3-Wire Serial Interface GND - Ground Wide Analog Power Supply Range (2.65V - V - Analog Supply Voltage DDA 5.5V) SDO - Serial Data Out Separate Digital Supply Allows for 1.8V SDI - Serial Data In Logic V - Digital Supply Voltage DDD Available in an 8-Pin SO (150mil) and 8-Pin MAX package DESCRIPTION The DS1722 Digital Thermometer and Thermostat with SPI/3-Wire Interface provides temperature readings which indicate the temperature of the device. No additional components are required the device is truly a temperature-to-digital converter. Temperature readings are communicated from the DS1722 over a Motorola SPI interface or a standard 3-wire serial interface. The choice of interface standard is selectable by the user. For applications that require greater temperature resolution, the user can adjust the readout resolution from 8 to 12 bits. This is particularly useful in applications where thermal runaway conditions must be detected quickly. For application flexibility, the DS1722 features a wide analog supply rail of 2.65V - 5.5V. A separate digital supply allows a range of 1.8V to 5.5V. The DS1722 is available in an 8-pin SO (150mil) and 8-pin MAX package. Applications for the DS1722 include personal computers/servers/workstations, cellular telephones, office equipment, or any thermally-sensitive system. 1 of 14 022008 DS1722 ORDERING INFORMATION Table 1 PART MARKING DESCRIPTION DS1722S DS1722 DS1722 in 150mil 8-Pin SO DS1722S/T&R DS1722 DS1722 in 150mil 8-Pin SO, 2500 Piece Tape-and- Reel DS1722S+ DS1722 DS1722 in Lead-Free 150mil 8-Pin SO (See note) DS1722S+T&R DS1722 DS1722 in Lead-Free 150mil 8-Pin SO, 2500 Piece (See note) Tape-and-Reel DS1722U 1722 DS1722 in 8-Pin MAX DS1722U/T&R 1722 DS1722 in 8-Pin MAX, 3000 Piece Tape-and- Reel DS1722U+ 1722 DS1722 in Lead-Free 8-Pin MAX (See note) DS1722U+T&R 1722 DS1722 in Lead-Free 8-Pin MAX, 3000 Piece (See note) Tape-and-Reel Note: A + will also be marked on the package next to the pin 1 indicator. DETAILED PIN DESCRIPTION Table 2 SOIC SYMBOL DESCRIPTION Digital Supply Voltage 1.8V-5.5V. Defines the top rails for the digital PIN 1 V DDD inputs and outputs. Chip Enable Must be asserted high for communication to take place for PIN 2 CE either the SPI or 3-wire interface. Serial Clock Input Used to synchronize data movement on the serial PIN 3 SCLK interface for either the SPI or 3-wire interface. PIN 4 GND Ground pin. Serial Data Output When SPI communication is selected, the SDO pin is the serial data output for the SPI bus. When 3-wire communication is PIN 5 SDO selected, this pin must be tied to the SDI pin (the SDI and SDO pins function as a single I/O pin when tied together.) Serial Data Input When SPI communication is selected, the SDI pin is the serial data input for the SPI bus. When 3-wire communication is selected, PIN 6 SDI this pin must be tied to the SDO pin (the SDI and SDO pins function as a single I/O pin when tied together.) Serial Interface Mode Input This pin selects which interface standard will PIN 7 SERMODE be used: SPI when connected to V standard 3-wire when connected to CC GND. PIN 8 V Analog Supply Voltage 2.65V 5.5V input power pin. DDA 2 of 14