Precision Temperature Sensor with Beta Compensation (for

The ADT7421 is a dual−channel digital thermometer and under/overtemperature alarm, intended for use in PCs and thermal

management systems. It is pin−and register−compatible with the ADM1032, ADT7461 and ADT7461A. The ADT7421 includes Beta Cancellation Technology. This enables accurate measurement of temperature from very small geometry

(45 nm) processes. Significant variations in the Beta factor can be observed when different currents are applied to transistors embedded in small geometry CPU’s. This leads to large temperature errors. The ADT7421 automatically cancels the effects of error induced by beta variations.

Features

•On−Chip and Remote Temperature Sensor

•0.25°C Resolution on Remote Channel

•1°C Resolution on Local Channel

•Automatically Cancels the Effect of Beta Variation in Thermal Transistors on Small Geometry CPU’s

•Automatically Cancels Up to 50 (Typical) of Resistance in Series with Remote Transistor

•Extended, Switchable Temperature Measurement Range 0°C to +125°C (default) or −40°C to +125°C

•Pin−and Register−Compatible with ADM1032, ADT7461, ADT7461A, EMC1402, and aSC7525

•2−Wire SMBus Serial Interface with SMBus Alert Support

•Programmable Over/Undertemperature Limits

•Offset Registers for System Calibration

•Up to Two Overtemperature Fail−Safe THERMOutputs

•Small 8−lead MSOP and SOP Packages

•These are Pb−Free Devices

Applications

•Desktop and Notebook Computers

•Industrial Controllers

•Smart Batteries

•Automotive