19-1495; Rev 1; 12/99 Remote Temperature Sensorwith SMBus Serial InterfaceMAX1618________________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 transistor—typically a low-cost, easily mounted 2N3904 NPN type—that replaces conventional ♦ No Calibration Required thermistors or thermocouples. Remote accuracy is ±3°C ♦ SMBus 2-Wire Serial Interface for multiple transistor manufacturers, with no calibration needed. The MAX1618 can also measure the die temper- ♦ Programmable Under/Overtemperature Alarms 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 ♦ Management Bus (SMBus™) Write Byte, Read Byte, Send Supports SMBus Alert Response Accuracy Byte, and Receive Byte commands to program the alarm ±3°C (+60°C to +100°C) thresholds and to read temperature data. The data format ±5°C (-55°C to +120°C) is 7 bits plus sign, with each bit corresponding to 1°C, in ♦ 3µA (typ) Standby Supply Current two’s complement format. Measurements can be done automatically and autonomously, with the 16Hz conversion ♦ 900µA (max) Supply Current in Autoconvert Mode 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 µMAX 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. The MAX1618 is available in a small (1.1mm high) 10-pin PARTTEMP. RANGEPIN-PACKAGE µMAX package. MAX1618MUB -55°C to +125°C 10 µMAX ________________________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 0.1µF 200Ω TOP VIEW VCC STBY 10k EACH ADD0 1 10 ALERT MAX1618 DXP SMBCLK CLOCK ADD1 2 9 SMBDATA MAX1618 SMBDATA DATA GND 3 8 SMBCLK DXN ALERT INTERRUPT DXN 4 7 STBY 2N3904 2200pF TO µC DXP 5 6 VCC ADD0 ADD1 GND µ MAX SMBus is a trademark of Intel Corp. †Patents Pending ________________________________________________________________ Maxim Integrated Products1For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at 1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com.