LM95231 Datasheet | National Semiconductor

Description The LM95231 is a precision dual remote diode temperature sensor (RDTS) that uses National’s Tru Therm technology. The 2-wire serial interface of the LM95231 is patible 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 Tru Therm technology that reduces nonideality processor to processor 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. Tru Therm 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 in the 90nm process or 2N3904. The LM95231 resolution format for remote temperature readings can be programmed to be 11-bits signed or un Key Specifications signed with the digital filtering disabled. When the filtering is j Remote Diode Temperature Accuracy enabled the resolution increases to 13-bits signed or unsigned. In the unsigned mode the LM95231 remote diode TA=30˚C to 50˚C, TD=45˚C to 85˚C ± 0.75 ˚C (max) .. readings can resolve temperatures above 127˚C. Local tem± 2.0 ˚C (max) TA=0˚C to 85˚C, TD=25˚C to 140˚C perature readings have a resolution of 9-bits plus sign. j Local Temperature Accuracy n Remote temperature readings without digital filtering: - 0.125 ˚C LSb - 10-bits plus sign or 11-bits programmable resolution - 11-bits resolves temperatures above 127 ˚C n Remote temperature readings with digital filtering: - 0.03125 ˚C LSb with filtering - 12-bits plus sign or 13-bits programmable resolution - 13-bits resolves temperatures above 127 ˚C n Local temperature readings: - 0.25 ˚C - 9-bits plus sign n Status register support n Programmable conversion rate allows user optimization of power...