Dual Remote and Local Temperature Sensor with TruTherm Technology and SMBus Interface

The LM95231 is a precision dual remote

diode temperature sensor (RDTS) that uses Texas Instruments’ TruTherm technology.

The 2-wire serial interface of the LM95231 is compatible with SMBus 2.0. The LM95231

can sense three temperature zones, it can measure the temperature of its own die as

well as two diode connected transistors. The LM95231 includes digital filtering and

an advanced input stage that includes analog filtering and TruTherm technology that

reduces processor-to-processor non-ideality spread. The diode connected transistors

can be a “thermal diode” as found in Intel and AMD processors or can simply be a

diode connected MMBT3904 transistor. TruTherm technology allows accurate measurement

of “thermal diodes” found on small geometry processes, 90nm and below. The LM95231

supports user selectable thermal diode non-ideality of either a Pentium 4 processor

on 90nm process or 2N3904.

The LM95231 resolution format for

remote temperature readings can be programmed to be 11-bits signed or unsigned with

the digital filtering disabled. When the filtering is enabled the resolution

increases to 13-bits signed or unsigned. In the unsigned mode the LM95231 remote

diode readings can resolve temperatures above 127°C. Local temperature readings have

a resolution of 9-bits plus sign.