ADM1021

a FEATURES Improved Replacement for MAX1617 On-Chip and Remote Temperature Sensing No Calibration Necessary 1؇ C Accuracy for On-Chip Sensor 3؇ C Accuracy for Remote Sensor Programmable Over/Under Temperature Limits Programmable Conversion Rate 2-Wire SMBus Serial Interface Supports System Management Bus (SMBus™) Alert 70 ␮A Max Operating Current 3 ␮ A Standby Current 3 V to 5.5 V Supply Small 16-Lead QSOP Package APPLICATIONS Desktop Computers Notebook Computers Smart Batteries Industrial Controllers Telecomms Equipment Instrumentation Low Cost Microprocessor System Temperature Monitor ADM1021 PRODUCT DESCRIPTION The ADM1021 is a two-channel digital thermometer and under/ over temperature alarm, intended for use in personal computers and other systems requiring thermal monitoring and management. The device can measure the temperature of a microprocessor using a diode-connected PNP transistor, which may be provided on-chip in the case of the Pentium® II or similar processors, or can be a low cost discrete NPN/PNP device such as the 2N3904/2N3906. A novel measurement technique cancels out the absolute value of the transistor’s base emitter voltage, so that no calibration is required. The second measurement channel measures the output of an on-chip temperature sensor, to monitor the temperature of the device and its environment. The ADM1021 communicates over a two-wire serial interface compatible with SMBus standards. Under and over temperature limits can be programmed into t...