LM95234

LM95234 Quad Remote Diode and Local Temperature Sensor with SMBus Interface and TruTherm Technology ADVANCE INFORMATION August 2006 LM95234 Quad Remote Diode and Local Temperature Sensor with SMBus Interface and TruTherm™ Technology General Description LM95234 is an 11-bit digital temperature sensor with a 2-wire System Management Bus (SMBus) interface that can monitor the temperature of four remote diodes as well as its own temperature. The LM95234 can be used to very accurately monitor the temperature of up to four external devices such as microprocessors, graphics processors or diodeconnected 2N3904s. The LM95234’s TruTherm technology allows sensing of 90nm or 65nm process thermal diodes accurately. The LM95234 reports temperature in two different formats for +127.875˚C/–128˚C range and 0˚C/255˚C range. The LM95234 TCRIT1, TCRIT2 and TCRIT3 outputs are triggered when any unmasked channel exceeds its corresponding programmable limit and can be used to shutdown the system, to turn on the system fans or as a microcontroller interrupt function. The current status of the TCRIT1, TCRIT2 and TCRIT3 pins can be read back from the status registers. Mask registers are available for further control of the TCRIT outputs. Two LM95234 remote temperature channels have programmable digital filters while the other two remote channels utilize a fault-queue to minimize unwanted TCRIT events when temperature spikes are encountered. For optimum flexibility and accuracy, each LM95234 channel includes registers for sub-micron process or 2N3904 diode model selection as well as offset correction. A three level address pin allows connection of up to 3 LM95234s to the same SMBus master. The LM95234 includes power saving functions such as: programmable conversion rate, shutdown mode, and turn off of unused channels. n TruTherm technology accurately senses sub-micron process thermal diodes n Programmable digital filters and analog front end filter n 0.125˚C LSb temperature resolution n 0.03125˚C LSb remote temperature resolution with digital filter enabled n +127.875˚C/–128˚C and 0˚C/255˚C remote ranges n Remote diode fault detection, model selection and offset correction n Mask and status register support n 3 programmable TCRIT outputs with programmable shared hysteresis and Fault-Queue n Programmable conversion rate and shutdown mode one-shot conversion control n SMBus 2.0 compatible interface, supports TIMEOUT n Three-level address pin n 14-pin LLP package Key Specifications j Local Temperature Accuracy j Remote Diode Temperature Accuracy j Supply Voltage j Average Supply Current (1Hz ± 2.0 ˚C (max) ± 0.75 ˚C (max) 3.0 V to 3.6 V 0.5 mA (typ) conversion rate) Applications n Processor/Computer System Thermal Management (e.g. Laptop, Desktop, Workstations, Server) n Electronic Test Equipment n Office Electronics Features n Accurately senses die temperature of 4 remote ICs or diode junctions and local temperature Connection Diagram LLP-14 20106301 TOP VIEW TruTherm™ is a trademark of National Semiconductor Corporation. © 2006 National Semiconductor Corporation DS201063 www.national.com LM95234 Ordering Information Part Number LM95234CISD LM95234CISDX Package Marking 95234CI 95234CI NS Package Number SDA14B (LLP-14) SDA14B (LLP-14) Transport Media 1000 Units on Tape and Reel 4500 Units on Tape and Reel Simplified Block Diagram 20106302 Pin Descriptions Label NC VDD Pin # 1 2 Function No Connect Positive Supply Voltage Input Typical Connection Not connected. May be left floating, connected to GND or VDD. DC Voltage from 3.0 V to 3.6 V. VDD should be bypassed with a 0.1µF capacitor in parallel with 100pF. The 100pF 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. www.national.com 2 LM95234 Pin Descriptions Label D4+ (Continued) Pin # 3 Function Diode Current Source Typical Connection To fourth 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 D4+ and D-. A 100 pF capacitor between D4+ and D- can be added and may improve perfomance in noisy systems. Float this pin if this thermal diode is not used. To third 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 D3+ and D-. A 100 pF capacitor between D3+ and D- can be added and may improve perfomance in noisy systems. Float this pin if this thermal diode is not used. To all Diode Cathodes. Common D- pin for all four remote diodes. To second 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 D-. A 100 pF capacitor between D2+ and D- can be added and may improve perfomance in noisy systems. Float this pin if this thermal diode is not used. To first 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 D-. A 100 pF capacitor between D1+ and D- can be added and may improve perfomance in noisy systems. Float this pin if this thermal diode is not used. System low noise ground. SMBus slave address select pin. Selects one of three addresses. Can be tied to VDD, GND, or to the middle of a resistor divider connected between VDD and GND. Critical temperature output 1. Requires pull-up resistor. Active "LOW". Critical temperature output 2. Requires pull-up resistor. Active "LOW". From and to Controller; may require an external pull-up resistor From Controller; may require an external pull-up resistor Critical temperature output 3. Requires pull-up resistor. Active "LOW". D3+ 4 Diode Current Source D− D2+ 5 6 Diode Return Current Sink Diode Current Source D1+ 7 Diode Current Source GND A0 8 9 Power Supply Ground Dgital Input TCRIT1 TCRIT2 SMBDAT SMBCLK TCRIT3 10 11 12 13 14 Digital Output, Open-Drain Digital Output, Open-Drain SMBus Bi-Directional Data Line, Open-Drain Output SMBus Clock Input Digital Output, Open-Drain 3 www.national.com LM95234 Typical Application 20106303 www.national.com 4 LM95234 Quad Remote Diode and Local Temperature Sensor with SMBus Interface and TruTherm Technology Physical Dimensions unless otherwise noted inches (millimeters) 14-Lead Molded Leadless Leadframe Package (LLP), Order Number LM95234CISD or LM95234CISDX NS Package Number SDA14B 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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