DS1626/DS1726 High-Precision 3-Wire Digital Thermometer and Thermostat www.maxim-ic.com DESCRIPTION FEATURES The DS1626 and DS1726 digital Temperature Measurements Require No thermometers/thermostats provide temperature External Components measurements and stand-alone thermostat Measure Temperatures from -55C to capability over a -55C to +125C range. The +125C (-67F to +257F) DS1626 offers 0.5C accuracy from 0C to DS1626: 0.5C Accuracy from 0C to +70C and the DS1726 has 1C accuracy from +70C -10C to +85C. The resolution of the measured DS1726: 1C Accuracy from -10C to temperature is user selectable from 9 to 12 bits. +85C Communication with the DS1626 and DS1726 is Output Resolution is User Selectable to 9, achieved through a 3-wire serial bus. 10, 11, or 12 Bits Wide Power-Supply Range (2.7V to 5.5V) The DS1626 and DS1726 offer thermostatic Convert Temperature to Digital Word in functionality with three dedicated thermostat 750ms (max) outputs (T , T , and T ), and HIGH LOW COM Stand-Alone Thermostat Capability overtemperature (T ) and undertemperature (T ) H L Thermostatic Settings are User Definable and user-programmable thresholds stored in on-chip Nonvolatile (NV) EEPROM. For stand-alone thermostat operation, Data is Read/Written Through a 3-Wire T and T can be programmed prior to H L Serial Interface installation, and the DS1626/DS1726 can be Available in 8-Pin SOP Package configured to automatically begin taking temperature measurements at power-up. Table 1 PIN CONFIGURATION summarizes the user-accessible registers. Figure 1 shows a functional diagram. TOP VIEW 1 8 V APPLICATIONS DQ DD DS1626 Thermostatic Controls 2 DS1726 7 T CLK/CNV HIGH Industrial Controls 3 6 RST T LOW Consumer Products 4 5 GND T COM Any Space-Constrained Thermally Sensitive Application SOP ORDERING INFORMATION PART TEMP RANGE PIN-PACKAGE TOP MARK DS1626U -55C to +125C 1626 8 SOP DS1626U+ -55C to +125C 8 SOP 1626 DS1626U/T&R -55C to +125C 8 SOP, 3000-Piece 1626 DS1626U+T&R -55C to +125C 1626 8 SOP, 3000-Piece DS1726U -55C to +125C 1726 8 SOP DS1726U+ -55C to +125C 8 SOP 1726 DS1726U/T&R -55C to +125C 8 SOP, 3000-Piece 1726 DS1726U+T&R -55C to +125C 8 SOP, 3000-Piece 1726 +Denotes a lead-free package. A + symbol will also be marked on the package near the Pin 1 indicator. T&R = Tape and reel. 1 of 12 REV: 071107 DS1626/DS1726 PIN DESCRIPTION PIN NAME FUNCTION 1 DQ Data Input/Output Pin (Tri-State) for 3-Wire Serial Communication Clock Input Pin for 3-Wire Serial Communication. Controls temperature 2 CLK/CNV measurements when the DS1626/DS1726 is configured as a stand-alone thermostat. 3 RST Reset Input Pin for 3-Wire Serial Communication 4 GND Ground Pin 5 T Thermostat Output Pin (Push-Pull) with Programmable Hysteresis COM 6 T Thermostat Output Pin (Push-Pull) with T Trip Point LOW L 7 T Thermostat Output Pin (Push-Pull) with T Trip Point HIGH H 8 V Supply Voltage. +2.7V to +5.5V input power pin. DD Table 1. DS1626/DS1726 REGISTER SUMMARY REGISTER NAME MEMORY REGISTER CONTENTS SIZE (USER ACCESS) TYPE AND POWER-UP/POR STATE Temperature Measured Temperature (Twos Complement) 12 Bits SRAM (Read Only) Power-Up/POR State: -60C (1100 0100 0000) Upper Alarm Trip Point (Twos Complement) T H 12 Bits EEPROM Power-Up/POR State: User Defined (Read/Write) Initial State from Factory: +15C (0000 1111 0000) Lower Alarm Trip Point (Twos Complement) T L 12 Bits EEPROM Power-Up/POR State: User Defined (Read/Write) Initial State from Factory: +10C (0000 1010 0000) Configuration Configuration and Status Information (Unsigned) (Various Bits are SRAM and 4MSbs = SRAM and 4LSbs = EEPROM 1 Byte Read/Write and Read EEPROM Power-Up/POR State: 1000XXXX (XXXX = User OnlySee Table 3) Defined) Figure 1. DS1626/DS1726 FUNCTIONAL DIAGRAM V DD CONFIGURATION REGISTER AND CONTROL LOGIC GND TEMPERATURE SENSOR AND ADC ADDRESS and TEMPERATURE REGISTER I/O CONTROL CLK/CNV T REGISTER H T COM SDA DIGITAL T HIGH RST COMPARATOR/LOGIC T LOW T REGISTER L 2 of 12