LM95231

LM95231 TruTherm Precision Dual Remote Diode Temperature Sensor with SMBus Interface ADVANCE INFORMATION February 2005 LM95231 TruTherm™ Precision Dual Remote Diode Temperature Sensor with SMBus Interface General Description The LM95231 is a precision dual remote diode temperature sensor (RDTS) that uses National’s 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 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. 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 in the 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. 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 consumption n Shutdown mode one-shot conversion control n SMBus 2.0 compatible interface, supports TIMEOUT n 8-pin MSOP package Key Specifications j Remote Diode Temperature Accuracy TA=30˚C to 50˚C, TD=45˚C to 85˚C j Local Temperature Accuracy ± 0.75 ˚C (max) ± 2.0 ˚C (max) TA=0˚C to 85˚C, TD=25˚C to 140˚C TA=0˚C to 85˚C Features n Accurately senses die temperature of remote ICs or diode junctions n Uses TruTherm technology for precision “thermal diode” temperature measurement n Thermal diode input stage with analog filtering n Thermal diode digital filtering n Pentium 4 90nm or 2N3904 non-ideality selection n Remote diode fault detection n On-board local temperature sensing j Supply Voltage j Supply Current ± 3.0 ˚C (max) 3.0 V to 3.6 V 2 mA (typ) Applications n Processor/Computer System Thermal Management (e.g. Laptop, Desktop, Workstations, Server) n Electronic Test Equipment n Office Electronics Connection Diagram MSOP-8 20120202 TOP VIEW TruTherm™ is a trademark of National Semiconductor Corporation. I2C ® is a registered trademark of Phillips Corporation. Pentium™ is a trademark of Intel Corporation. © 2005 National Semiconductor Corporation DS201202 www.national.com LM95231 Ordering Information Part Number LM95231CIMM LM95231CIMMX Package Marking LM95231CIMM LM95231CIMM NS Package Number MUA08A (MSOP-8) MUA08A (MSOP-8) Transport Media 1000 Units on Tape and Reel 3500 Units on Tape and Reel SMBus Device Address 010 1011 010 1011 Pin Descriptions Label D1+ Pin # 1 Function Diode Current Source Typical Connection To Diode Anode. Connected to remote discrete diode-connected transistor junction or to the diode-connected transistor junction on a remote IC whose die temperature is being sensed. A capacitor is not required between D1+ and D1-. A 100 pF capacitor between D1+ and D1− can be added and may improve performance in noisy systems. To Diode Cathode. A capacitor is not required between D1+ and D1-. A 100 pF capacitor between D1+ and D1− can be added and may improve performance in noisy systems. To Diode Anode. Connected to remote discrete diode-connected transistor junction or to the diode-connected transistor junction on a remote IC whose die temperature is being sensed. A capacitor is not required between D2+ and D2-. A 100 pF capacitor between D2+ and D2− can be added and may improve performance in noisy systems. To Diode Cathode. A capacitor is not required between D2+ and D2-. A 100 pF capacitor between D2+ and D2− can be added and may improve performance in noisy systems. System low noise ground DC Voltage from 3.0 V to 3.6 V. VDD should be bypassed with a 0.1 µF capacitor in parallel with 100 pF. The 100 pF capacitor should be placed as close as possible to the power supply pin. Noise should be kept below 200 mVp-p, a 10 µF capacitor may be required to achieve this. From and to Controller; may require an external pull-up resistor From Controller; may require an external pull-up resistor D1− 2 Diode Return Current Sink D2+ 3 Diode Current Source D2− 4 Diode Return Current Sink GND VDD 5 6 Power Supply Ground Positive Supply Voltage Input SMBDAT SMBCLK 7 8 SMBus Bi-Directional Data Line, Open-Drain Output SMBus Clock Input www.national.com 2 LM95231 Typical Application 20120203 3 www.national.com LM95231 TruTherm Precision Dual Remote Diode Temperature Sensor with SMBus Interface Physical Dimensions inches (millimeters) unless otherwise noted 8-Lead Molded Mini-Small-Outline Package (MSOP), JEDEC Registration Number MO-187 Order Number LM95231CIMM or LM95231CIMMX NS Package Number MUA08A National does not assume any responsibility for use of any circuitry described, no circuit patent licenses are implied and National reserves the right at any time without notice to change said circuitry and specifications. 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