MAX6674 Cold-Junction-Compensated K-Thermocouple- to-Digital Converter (0C to +128C) General Description Features The MAX6674 cold-junction-compensation thermocou- Cold-Junction Compensation ple-to-digital converter performs cold-junction compensa- Simple SPI-Compatible Serial Interface tion and digitizes the signal from a type-K thermocouple. 10 Bit, 0.125C The data is output in a 10-bit resolution, SPI-compatible, read-only format. Open Thermocouple Detection This converter resolves temperatures to 0.125C, allows readings as high as +128C, and exhibits thermocouple accuracy of 2C for temperatures ranging from 0C to Ordering Information +125C. The MAX6674 is available in a small, 8-pin SO package. PART TEMP RANGE PIN-PACKAGE MAX6674ISA -20C to +85C 8 SO Applications Industrial Appliances HVAC Pin Configuration TOP VIEW GND 1 8 N.C. T- 2 7 SO MAX6674 T+ 3 6 CS V 4 5 SCK CC SO Typical Application Circuit Vcc 0.1F MICROCONTROLLER 68HC11A8 MAX6674 GND MISO SO SCK T+ SCK CS SSB T- 19-2241 Rev 2 4/14MAX6674 Cold-Junction-Compensated K-Thermocouple- to-Digital Converter (0C to +128C) Absolute Maximum Ratings Supply Voltage (V to GND) ................................ -0.3V to +6V Storage Temperature Range ............................ -65C to +150C CC SO, SCK, CS, T-, T+ to GND .....................-0.3V to V + 0.3V Junction Temperature ......................................................+150C CC SO Current ........................................................................50mA SO Package ESD Protection (Human Body Model) .......................... 2000V Vapor Phase (60s) ......................................................+215C Continuous Power Dissipation (T = +70C) Infrared (15s) ..............................................................+220C A 8-Pin SO (derate 5.88mW/C above +70C) ...............471mW Lead Temperature (soldering, 10s) ................................ +300C Operating Temperature Range ........................... -20C to +85C Stresses beyond those listed under Absolute Maximum Ratings may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability. Electrical Characteristics (V = +3.0V to +5.5V, T = -20C to +85C, unless otherwise noted. Typical values specified at +25C.) (Note 1) CC A PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS TTHERMOCOUPLE = VCC = +3.3V -1 +1 +100C, TA = +25C VCC = +5V -1.5 +1.5 (Note 2) Temperature Error C TTHERMOCOUPLE = VCC = +3.3V -2 +2 0C to +125C, TA = VCC = +5V -3 +3 +25C (Note 2) Temperature Conversion 5.125 v/LSB Constant TA = +25C VCC = +3.3V -1 +1 Cold-Junction Compensation C TA = -20C to +85C VCC = +3.3V and -3 +3 +5V (Note 2) Resolution 0.125 C Thermocouple Input Impedance 20 kW Supply Voltage VCC 3.0 5.5 V Supply Current ICC 1 2 mA Power-On Reset Threshold VCC rising 1 2 2.5 V Power-On Reset Hysteresis 50 mV Conversion Time (Note 2) 0.15 0.18 s SERIAL INTERFACE 0.3 x Input Low Voltage VIL V VCC 0.7 x Input High Voltage VIH V VCC Input Leakage Current ILEAK VIN = GND or VCC -5 5 A Input Capacitance CIN 5 pF Maxim Integrated 2 www.maximintegrated.com