MAX1618 19-1495 Rev 1 12/99 Remote Temperature Sensor with SMBus Serial Interface General Description Features The MAX1618 precise digital thermometer reports the Single Channel: Measures Remote CPU temperature of a remote sensor. The remote sensor is a Temperature diode-connected transistortypically a low-cost, easily No Calibration Required mounted 2N3904 NPN typethat replaces conventional thermistors or thermocouples. Remote accuracy is 3C SMBus 2-Wire Serial Interface for multiple transistor manufacturers, with no calibration Programmable Under/Overtemperature Alarms needed. The MAX1618 can also measure the die temper- ature of other ICs, such as microprocessors, that contain Overtemperature Output for Fan Control an on-chip, diode-connected transistor. (Thermostat Mode) The 2-wire serial interface accepts standard System Supports SMBus Alert Response Accuracy Management Bus (SMBus) Write Byte, Read Byte, Send 3C (+60C to +100C) Byte, and Receive Byte commands to program the alarm 5C (-55C to +120C) thresholds and to read temperature data. The data format is 7 bits plus sign, with each bit corresponding to 1C, in 3A (typ) Standby Supply Current twos complement format. Measurements can be done 900A (max) Supply Current in Autoconvert Mode automatically and autonomously, with the 16Hz conversion rate or programmed to operate in a single-shot mode. +3V to +5.5V Supply Range The thermostat mode configures the ALERT output as an Small 10-Pin MAX Package interrupt or as a temperature reset that remains active only while the temperature is above the maximum temperature limit or below the minimum temperature limit. The ALERT output polarity in thermostat mode can be configured for active high or active low. Fan control is implemented using Ordering Information this ALERT output. PART TEMP. RANGE PIN-PACKAGE The MAX1618 is available in a small (1.1mm high) 10-pin MAX1618MUB -55C to +125C 10 MAX MAX package. Applications Desktop and Notebook Central Office Computers Telecom Equipment Smart Battery Packs Test and Measurement LAN Servers Multichip Modules Industrial Controls Typical Operating Circuit Pin Configuration 3V TO 5.5V 0.1 F 200 TOP VIEW V STBY CC 10k EACH MAX1618 ADD0 1 10 ALERT DXP CLOCK SMBCLK ADD1 2 9 SMBDATA MAX1618 DATA SMBDATA GND 3 8 SMBCLK DXN ALERT INTERRUPT DXN 4 7 STBY 2N3904 2200pF TO C DXP 5 6 V CC ADD0 ADD1 GND MAX SMBus is a trademark of Intel Corp. Patents Pending Maxim Integrated Products 1 For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct at 1-888-629-4642, or visit Maxims website at www.maxim-ic.com.Remote Temperature Sensor with SMBus Serial Interface ABSOLUTE MAXIMUM RATINGS V to GND..............................................................-0.3V to +6V Continuous Power Dissipation (T = +70C) CC A DXP, ADD to GND ....................................-0.3V to (V + 0.3V) MAX (derate 5.6mW/C above +70C) ....................444mW CC DXN to GND ..........................................................-0.3V to +0.8V Operating Temperature Range (extended)......-55C to +125C SMBCLK, SMBDATA, ALERT, STBY to GND ...........-0.3V to +6V Junction Temperature.....................................................+150C SMBDATA Current.................................................-1mA to 50mA Storage Temperature Range ............................-65C to +150C DXN Current.....................................................................1mA Lead Temperature (soldering, 10s) ................................+300C ESD Protection (all pins, Human Body Model)............... 2000V 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 = +3.3V, configuration byte register = X8h, T = 0C to +85C, unless otherwise noted.) CC A PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS ADC AND POWER SUPPLY Temperature Resolution Monotonicity guaranteed 8 Bits (Note 1) -3 3 T = +60C to +100C Temperature Error, R C Remote Diode (Note 2) T = +55C to +125C -5 5 R Supply-Voltage Range V 3 5.5 V CC Undervoltage Lockout V input, disables A/D conversion, CC UVLO 2.6 2.8 2.95 V Threshold rising edge Undervoltage Lockout Hysteresis 50 mV Power-On Reset Threshold V , falling edge 1 1.7 2.5 V CC POR Threshold Hysteresis 50 mV Standby Supply Current SMBus static 310 A Hardware or software standby, Standby Supply Current 5 A SMBCLK at 10kHz Average Operating Autoconvert mode, average measured overAutoconvert 450 900 A Supply Current 4sec, 16 conv/sec mode, average Conversion Time t From stop bit to conversion complete 47 62 78 ms CONV Conversion Rate Timing Error Autoconvert mode -25 25 % High level 80 100 120 DXP forced to DXN + 0.65V, Remote-Diode Source Current A ID = 1 (high) Low level 810 12 DXN Source Voltage 0.7 V ADDO, ADD1 Bias Current Momentary upon power-on reset 160 A SMBus INTERFACE STBY SMBCLK, SMBDATA V V = 3.0V 2.2 V IH CC Input High Voltage STBY, SMBCLK, SMBDATA V V = 3.0V to 5.5V 0.8 V IL CC Input Low Voltage STBY, SMBCLK, SMBDATA Logic inputs forced to V or GND -1 1 A CC Input Current SMBCLK, SMBDATA SMBCLK, SMBDATA forced to 0.4V 6 mA Output Low Sink Current 2 MAX1618