ADM1023

a FEATURES Next Generation Upgrade to ADM1021 On-Chip and Remote Temperature Sensing Offset Registers for System Calibration 1 ؇ C Accuracy and Resolution on Local Channel 0.125؇ C Resolution/1؇ C Accuracy on Remote Channel Programmable Over/Under Temperature Limits Programmable Conversion Rate Supports System Management Bus (SMBus) Alert 2-Wire SMBus Serial Interface 200 ␮A Max Operating Current (0.25 Conversions/ Seconds) 1 ␮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 ACPI-Compliant High-Accuracy Microprocessor System Temperature Monitor ADM1023* PRODUCT DESCRIPTION The ADM1023 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. Optimized for the Pentium® III; the higher accuracy offered allows systems designers to safely reduce temperature guard banding and increase system performance. 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 III 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 measu...