LM95245 www.ti.com SNIS148G – OCTOBER 2007 – REVISED MARCH 2013 Precision Remote Diode Digital Temperature Sensor with TruTherm® BJT Beta Compensation Technology for 45nm Process Check for Samples: LM95245 FEATURES DESCRIPTION • • • The LM95245 is an 11-bit digital temperature sensor with a 2-wire System Management Bus (SMBus) interface and TruTherm technology that can monitor the temperature of a remote diode as well as its own temperature. The LM95245 can be used to very accurately monitor the temperature of external devices such as microprocessors. TruTherm technology allows the LM95245 to precisely monitor thermal diodes found in 90 nm and smaller geometry processes. The LM95245 is specifically targeted for Intel processors on 45nm process. LM95245 reports temperature in two different formats for +127.875°C/128°C range and 0°C/255°C range. The LM95245 T_CRIT and OS outputs are asserted when either unmasked channel exceeds its programmed 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 T_CRIT and OS pins can be read back from the status registers via the SMBus interface. All limits have a shared programmable hysteresis register. 1 2 • • • • • • • • • • • Remote and Local Temperature Channels Targeted for Intel 45nm Processor Diodes Two Formats: −128°C to +127.875°C and 0°C to 255.875°C Digital Filter for Remote Channel Programmable TCRIT and OS Thresholds Programmable Shared Hysteresis Register Diode Fault Detection Mask, Offset, and Status Registers SMBus 2.0 Compatible Interface, Supports TIMEOUT Programmable Conversion Rate for Best Power Consumption Three-Level Address Pin Standby Mode One-Shot Conversion Control Pin-for-Pin Compatible With the LM95235 and LM86, LM89, LM99 8-Pin VSSOP and SOIC Packages APPLICATIONS • • • Processor/Computer System Thermal Management (For Example, Laptops, Desktops, Workstations, Servers) Electronic Test Equipment Office Electronics KEY SPECIFICATIONS • • • • • Supply Voltage 3.0 to 3.6 V Supply Current, Conv. Rate = 1 Hz 350 µA (typ) Remote Diode Temperature Accuracy – TA = 25°C to 85°C; TD = 50°C to 105°C, ±0.75 °C (max) – TA = 25°C to 85°C; TD = 40°C to 125°C, ±1.5 °C (max) Local Temperature Accuracy – TA = 25°C to 100°C, ±2.0 °C (max) Conversion Rate, Both Channels 16 to 0.4 Hz The remote temperature channel of the LM95245 has a programmable digital filter. The LM95245 is targeted for a typical Intel® processor on a 45 nm, 65 nm or 90nm process, and has an offset register for maximum flexibility and best accuracy. The LM95245 has a three-level address pin to connect up to 3 devices to the same SMBus master, that is shared with the OS output. The LM95245 has a programmable conversion rate register and a standby mode to save power. One conversion can be triggered in standby mode by writing to the one-shot register. 1 2 Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of Texas Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet. All trademarks are the property of their respective owners. PRODUCTION DATA information is current as of publication date. Products conform to specifications per the terms of the Texas Instruments standard warranty. Production processing does not necessarily include testing of all parameters. Copyright © 2007–2013, Texas Instruments Incorporated LM95245 SNIS148G – OCTOBER 2007 – REVISED MARCH 2013 www.ti.com Connection Diagram Top View VDD 1 8 SMBCLK D+ D- 2 7 SMBDAT 6 T_CRIT 4 OS/A0 GND 3 LM95245 5 Figure 1. VSSOP-8 and SOIC-8 Packages see package numbers DGK0008A, D0008A Simplified Block Diagram 3.0V-3.6V 1 LM95245 Local Diode Selector D+ D- 2 3 Temperature Sensor Circuitry Remote Diode Selector General Config Control Registers Logic 4 + - 6 ' Converter 6 + - TruTherm & Diode Config Registers Status Registers Limit & Hyst Registers Local Temp Registers Remote Temp Registers OS/A0 ID Registers 7 SMBus Serial Interface T_CRIT 8 SMBDAT SMBCLK 5 Table 1. Pin Descriptions 2 Pin Number Name Type 1 VDD Power 2 D+ Analog Input/Output Positive input from the thermal diode. 3 D- Analog Input/Output Negative input from the thermal diode. 4 T_CRIT Digital Output 5 GND Ground Description Device power supply. Requires bypass capacitor of 10 µF in parallel with 0.1 µF and 100 pF. Place 100 pF closest to device pin. Critical temperature output. Open-drain output requires pull-up resistor. Active low. Device ground. 6 OS/A0 Digital Input/Output Over-temperature shutdown comparator output or SMBus slave address input. Defaults as an SMBus slave address input that selects one of three addresses. Can be tied to VDD, GND, or to the middle of a resistor divider connected between VDD and GND. When programmed as an OS comparator output it is active low and open drain. 7 SMBDAT Digital Input/Output SMBus interface data pin. Open-drain output requires pull-up resistor. 8 SMBCLK Digital Input SMBus interface clock pin. Submit Documentation Feedback Copyright © 2007–2013, Texas Instruments Incorporated Product Folder Links: LM95245 LM95245 www.ti.com SNIS148G – OCTOBER 2007 – REVISED MARCH 2013 Typical Application +3.3V Standby C4 10 µF C3 0.1 µF C2 100 pF R1 1.3k Place capacitor C2 close to LM95245 2 Processor Place close to LM95245 Main CPU Voltage R3 1.3k R4 1.3k SMBus Master LM95245 1 C1 100 pF R2 1.3k 3 4 VDD SMBCLK D+ SMBDAT D- T_CRIT OS/A0 GND 8 7 6 5 SMBCLK SMBDAT ALERT SMI Shutdown Control Power Supply Submit Documentation Feedback Copyright © 2007–2013, Texas Instruments Incorporated Product Folder Links: LM95245 3 LM95245 SNIS148G – OCTOBER 2007 – REVISED MARCH 2013 www.ti.com These devices have limited built-in ESD protection. The leads should be shorted together or the device placed in conductive foam during storage or handling to prevent electrostatic damage to the MOS gates. (1) (2) Absolute Maximum Ratings Supply Voltage, VDD −0.3V to 6.0V Voltage at SMBDAT, SMBCLK, T_CRIT, OS/A0 Pins −0.5V to 6.0V Voltage at Other Pins (VDD +0.3V) (3) Input Current at D− Pin ±1 mA Input Current at All Other Pins ±5 mA (3) Output Sink Current, SMBDAT, T_Crit, OS Pins Package Input Current 10 mA (3) 30 mA Human Body Model ESD Susceptibility (4) 2500V Machine Model 250V Charged Device Model Junction Temperature 1000V (5) +125°C −65°C to +150°C Storage Temperature (1) (2) (3) (4) (5) Absolute Maximum Ratings indicate limits beyond which damage to the device may occur. Operating Ratings indicate conditions for which the device is guaranteed to be functional, but do not guarantee specific performance limits. For guaranteed specifications and test conditions, see the Electrical Characteristics. The guaranteed specifications apply only for the test conditions listed. Some performance characteristics may degrade when the device is not operated under the listed test conditions. Operation of the device beyond the maximum Operating Ratings is not recommended. Soldering process must comply with Reflow Temperature Profile specifications. Refer to www.ti.com/packaging. Reflow temperature profiles are different for packages containing lead (Pb) than for those that do not. When the input voltage (VI) at any pin exceeds the power supplies (VI < GND or VI > VDD), the current at that pin should be limited to 5 mA. Parasitic components and or ESD protection circuitry are shown in Table 2 for the LM95245's pins. Care should be taken not to forward bias the parasitic diodes on pins 2 and 3. Doing so by more than 50 mV may corrupt the temperature measurements. SNP refers to Snap-back device. Human body model (HBM) is a charged 100 pF capacitor discharged into a 1.5 kΩ resistor. Machine model (MM), is a charged 200 pF capacitor discharged directly into each pin. Charged Device Model (CDM) simulates a pin slowly acquiring charge (such as from a device sliding down the feeder in an automated assembler) then rapidly being discharged. Thermal resistance junction-to-ambient when attached to a printed circuit board with 1 oz. foil and no airflow is: θJA for VSSOP-8 package = 210°C/WθJA for SOIC-8 package = 168°C/W Table 2. ESD Protection Pin No. Label Circuit 1 VDD B 2 D+ A Pin ESD Protection Structure Circuits V+ V+ D2 ESD Clamp PIN 3 D− A D1 D3 6.5V ESD CLAMP T_CRIT C 5 GND B 6 OS/A0 C 160 k D3 80 k GND GND 4 D2 D1 6.5V Circuit A Circuit B PIN D1 SNP 7 SMBDAT C GND 8 4 SMBCLK C Circuit C Submit Documentation Feedback Copyright © 2007–2013, Texas Instruments Incorporated Product Folder Links: LM95245 LM95245 www.ti.com SNIS148G – OCTOBER 2007 – REVISED MARCH 2013 Operating Ratings (1) Operating Temperature Range -40°C to +125°C Electrical Characteristics Temperature Range, TMIN ≤ TA ≤ TMAX -40°C ≤ TA ≤ +85°C Supply Voltage (VDD) (1) +3.0V to +3.6V Absolute Maximum Ratings indicate limits beyond which damage to the device may occur. Operating Ratings indicate conditions for which the device is guaranteed to be functional, but do not guarantee specific performance limits. For guaranteed specifications and test conditions, see the Electrical Characteristics. The guaranteed specifications apply only for the test conditions listed. Some performance characteristics may degrade when the device is not operated under the listed test conditions. Operation of the device beyond the maximum Operating Ratings is not recommended. Temperature-to-Digital Converter Characteristics Unless otherwise noted, these specifications apply for VDD = +3.0 Vdc to 3.6 Vdc. Boldface limits apply for TA = TJ = TMIN ≤ TA ≤ TMAX; all other limits TA = TJ = +25°C, unless otherwise noted. TJ is the junction temperature of the LM95245. TD is the junction temperature of the remote thermal diode. Parameter Test Conditions Typ (1) Limits (2) Unit (Limit) ±1 ±2 °C (max) ±6 °C (max) Temperature Accuracy Using Local Diode (3) TA = 25°C to +100°C Temperature Accuracy Using Remote Diode (4) TA = +25°C to +85°C; TD = +50°C to +105°C 45nm Intel Processor ±0.5 ±0.75 °C (max) TA = +25°C to +85°C; TD = +40°C to +120°C 45nm Intel Processor ±0.75 ±1.5 °C (max) TA = -40°C to +25°C; TD = +25°C to +125°C 45nm Intel Processor ±3.0 °C (max) TA = -40°C to +25°C 11 Digital Filter Off Remote Diode Measurement Resolution Digital Filter On Local Diode Measurement Resolution Bits 0.125 °C 13 Bits 0.03125 °C 11 Bits 0.125 Conversion Time, Fastest Setting (5) Local and Remote Channels 63 Local or Remote Channels Quiescent Current SMBus Inactive, 1 Hz conversion rate 33 (6) Standby Mode D− Source Voltage External Diode Current Source °C 72 350 ms 670 µA (max) 300 µA 400 mV High-level 172 Low-level 10.75 Diode Source Current Ratio ms (max) 225 µA (max) µA 16 Power-On Reset Voltage 2.8 V (max) 1.6 V (min) T_CRIT Pin Temperature Threshold Default +110 °C OS Pin Temperature Threshold Default +85 °C (1) (2) (3) (4) (5) (6) Typical figures are at TA = 25°C and represent most likely parametric norms at the time of product characterization. The typical specifications are not guaranteed. Limits are guaranteed to TI's AOQL (Average Outgoing Quality Level). Local temperature accuracy does not include the effects of self-heating. The rise in temperature due to self-heating is the product of the internal power dissipation of the LM95245 and the thermal resistance. See () for the thermal resistance to be used in the self-heating calculation. The accuracy of the LM95245 is guaranteed when using a typical thermal diode of an Intel processor on a 45 nm process, as selected in the Remote Diode Model Select register. See typical performance curve for performance with Intel processor on a 65nm or 90nm process. This specification is provided only to indicate how often temperature data is updated. The LM95245 can be read at any time without regard to conversion state (and will yield last conversion result). Quiescent current will not increase substantially when the SMBus is active. Submit Documentation Feedback Copyright © 2007–2013, Texas Instruments Incorporated Product Folder Links: LM95245 5 LM95245 SNIS148G – OCTOBER 2007 – REVISED MARCH 2013 www.ti.com Logic Electrical Characteristics Digital DC Characteristics Unless otherwise noted, these specifications apply for VDD= +3.0 Vdc to 3.6 Vdc. Boldface limits apply for TA = TJ = TMIN to TMAX; all other limits TA= TJ= +25°C, unless otherwise noted. Parameter Test Conditions Typ (1) Limits (2) Unit (Limit) SMBDAT, SMBCLK INPUTS VIN(1) Logical “1” Input Voltage 2.1 V (min) VIN(0) Logical “0” Input Voltage 0.8 V (max) VIN(HYST) SMBDAT and SMBCLK Digital Input Hysteresis IIN(1) Logical “1” Input Current VIN = VDD −0.005 −10 µA (max) IIN(0) Logical “0” Input Current VIN = 0 V 0.005 +10 µA (max) CIN Input Capacitance 400 mV 5 pF A0 DIGITAL INPUT VIH Input High Voltage VIM Input Middle Voltage VIL Input Low Voltage IIN(1) Logical “1” Input Current VIN = VDD IIN(0) Logical “0” Input Current VIN = 0 V CIN Input Capacitance 0.90 × VDD V (min) 0.57 × VDD V (max) 0.43 × VDD V (min) 0.10 × VDD V (max) −0.005 −10 µA (max) 0.005 +10 µA (max) 5 pF SMBDAT, T_CRIT, OS DIGITAL OUTPUTS IOH High Level Output Leakage Current VOUT = VDD 10 µA (max) VOL(T_CRIT, OS) T_CRIT, OS Low Level Output Voltage IOL = 6 mA 0.4 V (max) VOL(SMBDAT) SMBDAT Low Level Output Voltage IOL = 4 mA IOL = 6 mA 0.4 0.6 V (max) V (max) COUT Digital Output Capacitance (1) (2) 6 5 pF Typical figures are at TA = 25°C and represent most likely parametric norms at the time of product characterization. The typical specifications are not guaranteed. Limits are guaranteed to TI's AOQL (Average Outgoing Quality Level). Submit Documentation Feedback Copyright © 2007–2013, Texas Instruments Incorporated Product Folder Links: LM95245 LM95245 www.ti.com SNIS148G – OCTOBER 2007 – REVISED MARCH 2013 SMBus Digital Switching Characteristics Unless otherwise noted, these specifications apply for VDD= +3.0 Vdc to +3.6 Vdc, CL (load capacitance) on output lines = 80 pF. Boldface limits apply for TA = TJ = TMIN to TMAX; all other limits TA = TJ = +25°C, unless otherwise noted. The switching characteristics of the LM95245 fully meet or exceed the published specifications of the SMBus version 2.0. The following parameters are the timing relationships between SMBCLK and SMBDAT signals related to the LM95245. They adhere to, but are not necessarily, the SMBus specifications. Parameter Typ (1) Test Conditions Limits (2) Unit (Limit) 100 10 kHz (max) kHz (min) 4.7 25 µs (min) ms (max) fSMB SMBus Clock Frequency tLOW SMBus Clock Low Time from VIN(0)max to VIN(0)max tHIGH SMBus Clock High Time from VIN(1)min to VIN(1)min tR,SMB SMBus Rise Time (3) 1 µs (max) tF,SMB SMBus Fall Time (4) 0.3 µs (max) tOF Output Fall Time tTIMEOUT tSU;DAT 4.0 CL = 400 pF, IO = 3 mA, (4) µs (min) 250 ns (max) SMBDAT and SMBCLK Time Low for Reset of Serial Interface (5) 25 35 ms (min) ms (max) Data In Setup Time to SMBCLK High 250 ns (min) tHD;DAT Data Out Stable after SMBCLK Low 300 1075 ns (min) ns (max) tHD;STA Start Condition SMBDAT Low to SMBCLK Low (Start condition hold before the first clock falling edge) 100 ns (min) tSU;STO Stop Condition SMBCLK High to SMBDAT Low (Stop Condition Setup) 100 ns (min) tSU;STA SMBus Repeated Start-Condition Setup Time, SMBCLK High to SMBDAT Low 0.6 µs (min) tBUF SMBus Free Time Between Stop and Start Conditions 1.3 µs (min) (1) (2) (3) (4) (5) Typical figures are at TA = 25°C and represent most likely parametric norms at the time of product characterization. The typical specifications are not guaranteed. Limits are guaranteed to TI's AOQL (Average Outgoing Quality Level). The output rise time is measured from (VIN(0)max - 0.15V) to (VIN(1)min + 0.15V). The output fall time is measured from (VIN(1)min + 0.15V) to (VIN(0)max - 0.15V). Holding the SMBDAT and/or SMBCLK lines Low for a time interval greater than tTIMEOUT will reset the LM95245's SMBus state machine, therefore setting SMBDAT and SMBCLK pins to a high impedance state. tLOW tR tF VIH SMBCLK VIL tHD;STA tHD;DAT tBUF tHIGH tSU;STA tSU;DAT tSU;STO VIH SMBDAT VIL P S S P Figure 2. SMBus Communication Submit Documentation Feedback Copyright © 2007–2013, Texas Instruments Incorporated Product Folder Links: LM95245 7 LM95245 SNIS148G – OCTOBER 2007 – REVISED MARCH 2013 www.ti.com Typical Performance Characteristics 8 Thermal Diode Capacitor or PCB Leakage Current Effect Remote Diode Temperature Reading Remote Temperature Reading Sensitivity to Thermal Diode Filter Capacitance, TruTherm Enabled Figure 3. Figure 4. Conversion Rate Effect on Average Power Supply Current Intel Processor on 45nm, 65nm, or 90 nm Porcess Thermal Diode Performance Comparison Figure 5. Figure 6. Submit Documentation Feedback Copyright © 2007–2013, Texas Instruments Incorporated Product Folder Links: LM95245 LM95245 www.ti.com SNIS148G – OCTOBER 2007 – REVISED MARCH 2013 FUNCTIONAL DESCRIPTION The LM95245 is a temperature sensor that measures Local and Remote temperature zones. The LM95245 uses a ΔVbe temperature sensing method. A differential voltage, representing temperature, is digitized using a SigmaDelta analog to digital converter. TruTherm BJT (Transistor) Beta Compensation Technology allows the LM95245 to accurately sense the temperature of a thermal diode found on die fabricated using a sub-micron process. For more information on TruTherm Technology see Applications Hints . The LM95245 is compatible with the serial SMBus version 2.0 two-wire serial interface. The LM95245 has OS and TCRIT open-drain digital outputs that indicate the state of the local and remote temperature readings when compared to user-programmable limits. If enabled, the local temperature is compared to the user-programmable Local Shared OS and TCRIT Limit Register (Default Value = 85°C). The comparison result can trigger the T_CRIT pin and/or the OS pin depending on the settings of the Local TCRIT Mask and OS Mask bits found in Configuration Register 1. The comparison result can also be read back from Status Register 1. If enabled, the remote temperature is compared to the user-programmable Remote TCRIT Limit Register (Default Value = 110°C), and the Remote OS Limit Register (Default Value = 85°C) values. The comparison result can trigger the T_CRIT pin and/or the OS pin depending on the settings of Configuration Register 1. The following table describes the default temperature settings for each measured temperature that triggers T_CRIT and/or OS pins: Output Pin Remote, °C Local, °C T_CRIT 110 85 OS 85 85 The following table describes the limit register mapping to the T_CRIT and/or OS pins: Output Pin Remote Local T_CRIT Remote TCRIT Limit Local Shared OS/TCRIT Limit OS Remote OS Limit Local Shared OS/TCRIT Limit The T_CRIT and OS outputs are open-drain, active low. The remote temperature readings support a programmable digital filter. Based on the settings in Configuration Register 2 a digital filter can be turned on to improve the noise performance of the remote temperature as well as to increase the resolution of the temperature reading. If the filter is enabled the filtered readings are used for TCRIT and OS comparisons. The LM95245 may be placed in low power consumption (Standby) mode by setting the STOP/RUN bit found in Configuration Register 1. In the Standby mode, the LM95245’s SMBus interface remains active while all circuitry not required is turned off. In the Standby mode the host can trigger one round of conversions by writing to the One-Shot Register. The value written into this register is not kept. Local and Remote temperatures will be converted once and the T_CRIT and OS pins will reflect the comparison results based on this set of conversions results. All the temperature readings are in 16-bit left-justified word format. The 10-bit plus sign local temperature reading is contained in two 8-bit registers: Local Temp MSB and Local Temp LSB Registers. The remote temperature supports both a 13-bit unsigned and a 12-bit plus sign format. These readings are available in their corresponding registers as described in Table 8. The lower 2-bits of the remote temperature reading will contain temperature information only if the digital filter is enabled. If the digital filter is disabled, these two bits will read back 0. The signed and unsigned remote temperature readings are available simultaneously in separate registers, therefore allowing both negative temperatures and temperatures 128°C and above to be measured. All Limit Registers support unsigned temperature format with 1°C LSb resolution. The Local Shared TCRIT and OS Limit Register is 7 bits for limits between 0°C and 127°C. The Remote Temperature TCRIT and OS Limit Registers are 8 bits each for limits between 0°C and 255°C. Submit Documentation Feedback Copyright © 2007–2013, Texas Instruments Incorporated Product Folder Links: LM95245 9 LM95245 SNIS148G – OCTOBER 2007 – REVISED MARCH 2013 www.ti.com CONVERSION SEQUENCE In the power-up default state the LM95245 takes a maximum of 1 second to convert the Local Temperature, Remote Temperature, and to update all of its registers. Only during the conversion process is the Busy bit (D7) in Status Register 1 (02h) high. These conversions are addressed in a round-robin sequence. The conversion rate may be modified by the Conversion Rate bits found in the Conversion Rate Register (R/W: 04h/0Ah). When the conversion rate is modified a delay is inserted between conversions, the actual maximum conversion time remains at 72 ms. Different conversion rates will cause the LM95245 to draw different amounts of supply current as shown in Figure 7. Figure 7. Conversion Rate Effect on Power Supply Current POWER-ON-DEFAULT STATES LM95245 always powers up to these known default states. The LM95245 remains in these states until after the first conversion. 1. Command Register set to 00h 2. Conversion Rate register defaults to 02h (1 second). 3. Local Temperature set to 0°C until the end of the first conversion 4. Remote Diode Temperature set to 0°C until the end of the first conversion 5. Remote OS limit default is 55h (85 °C). 6. Local Shared and TCRIT limit default is 55h (85 °C). 7. Remote TCRIT limit default is 6Eh (110 °C). 8. Remote Offset High and Low bytes default to 00h. 9. Configuration Register 1 defaults to 00h. This sets the LM95245 as follows: (a) The STOP/RUN defaults to the active/converting mode. (b) The Local and Remote TCRIT and OS Masks are reset to 0. 10. Configuration Register 2 defaults to 1Fh. This sets the LM95245 as follows: (a) Remote Diode digital filter defaults on. (b) The Remote Diode mode defaults to a typical Intel processor on 45/65/90 nm process. (c) Diode Fault Mask bit for TCRIT defaults to 1. (d) Diode Fault Mask bit for OS defaults to 0. (e) Pin 6 Function defaults to Address Input function (A0). 10 Submit Documentation Feedback Copyright © 2007–2013, Texas Instruments Incorporated Product Folder Links: LM95245 LM95245 www.ti.com SNIS148G – OCTOBER 2007 – REVISED MARCH 2013 SMBus INTERFACE The LM95245 operates as a slave on the SMBus, so the SMBCLK line is an input and the SMBDAT line is bidirectional. The LM95245 never drives the SMBCLK line and it does not support clock stretching. According to SMBus specifications, the LM95245 has a 7-bit slave address. Three SMBus addresses can be selected by connecting pin 6 (A0) to either Low, Mid-Supply or High voltages. The address selection table below shows two sets of possible selections for the LM95245CIMM and the LM95245CIMM-1. State of the A0 Pin LM95245CIMM SMBus Device Address LM95245CIMM-1 SMBus Device Address HEX Binary HEX Binary Low 18 001 1000 19 001 1001 Mid-Supply 29 010 1001 29 010 1001 High 4C 100 1100 4D 100 1100 The OS/A0 pin, after power-up, defaults as an address select input pin (A0). After power-up, the OS/A0 pin can only be programmed as an OS output when it is in the “High” state. Therefore, 4Ch is the only valid slave address that can be used when the OS/A0 pin is programmed to function as an OS output. When the OS/A0 pin is programmed to function as an A0 input the LM95245 will immediately detect the state of this pin to determine its SMBus slave address. The LM95245 does not latch the state of the A0 pin when it is functioning as an input. If the OS/A0 pin is not used it must be externally connected through hardware to some state, as shown in the table, in order to guarantee that the proper address is selected and not in an indeterminate state. The OS/A0 does not have an internal pull-up. DIGITAL FILTER In order to suppress erroneous remote temperature readings due to noise, the LM95245 incorporates a digital filter for the Remote Temperature Channel. The filter is accessed in the Configuration Register 2, bits D2 (FE1) and D1(FE0). The filter can be set according to the following table. FE1 FE0 0 0 Filter Setting Filter Off 0 1 Reserved 1 0 Reserved 1 1 Filter On Filter Impulse and Step Response Curves depicts the filter output in response to a step input and an impulse input. Filter Impulse and Step Response Curves Figure 8. Seventeen and Fifty Degree Step Response Figure 9. Impulse Response with Input Transients Less Than 4°C Submit Documentation Feedback Copyright © 2007–2013, Texas Instruments Incorporated Product Folder Links: LM95245 11 LM95245 SNIS148G – OCTOBER 2007 – REVISED MARCH 2013 www.ti.com Figure 10. Impuse Response with Input Transients Greater Than 4°C Figure 11 shows the filter in use in a typical Intel processor on a 45/65/90 nm process system. Note that the two curves have been purposely offset for clarity. Inserting the filter does not induce an offset as shown. 45 LM95245 with Filter Off 43 TEMPERATURE (oC) 41 39 37 35 LM95245 with Filter On 33 31 29 27 25 0 50 100 150 200 SAMPLE NUMBER Figure 11. Digital Filter Response in a Typical Intel Processor on a 45nm, 65 nm or 90 nm Process (Filter Curves Were Purposely Offset for Clarity) TEMPERATURE DATA FORMAT Temperature data can only be read from the Local and Remote Temperature registers. Remote temperature data with the digital filter off is represented by an 10-bit plus sign, two's complement word and 11-bit unsigned binary word with an LSb (Least Significant Bit) equal to 0.125°C. The data format is a left justified 16-bit word available in two 8-bit registers. Unused bits report "0". Remote temperature data with the digital filter on is represented by a 12-bit plus sign, two's complement word and 13-bit unsigned binary word with an LSb (Least Significant Bit) equal to 0.03125°C (1/32°C). The data format is a left justified 16-bit word available in two 8-bit registers. Unused bits report "0". Table 3. 11-Bit, 2's Complement (10-Bit Plus Sign) Temperature 12 Digital Output Binary Hex +125°C 0111 1101 0000 0000 7D00h +25°C 0001 1001 0000 0000 1900h +1°C 0000 0001 0000 0000 0100h +0.125°C 0000 0000 0010 0000 0020h 0°C 0000 0000 0000 0000 0000h Submit Documentation Feedback Copyright © 2007–2013, Texas Instruments Incorporated Product Folder Links: LM95245 LM95245 www.ti.com SNIS148G – OCTOBER 2007 – REVISED MARCH 2013 Table 3. 11-Bit, 2's Complement (10-Bit Plus Sign) (continued) Temperature Digital Output Binary Hex −0.125°C 1111 1111 1110 0000 FFE0h −1°C 1111 1111 0000 0000 FF00h −25°C 1110 0111 0000 0000 E700h −55°C 1100 1001 0000 0000 C900h Table 4. 11-Bit, Unsigned Binary Temperature Digital Output Binary Hex +255.875°C 1111 1111 1110 0000 FFE0h +255°C 1111 1111 0000 0000 FF00h +201°C 1100 1001 0000 0000 C900h +125°C 0111 1101 0000 0000 7D00h +25°C 0001 1001 0000 0000 1900h +1°C 0000 0001 0000 0000 0100h +0.125°C 0000 0000 0010 0000 0020h 0°C 0000 0000 0000 0000 0000h Table 5. 13-Bit, 2's Complement (12-Bit Plus Sign) Temperature Digital Output Binary Hex +125°C 0111 1101 0000 0000 7D00h +25°C 0001 1001 0000 0000 1900h +1°C 0000 0001 0000 0000 0100h +0.03125°C 0000 0000 0000 1000 0008h 0°C 0000 0000 0000 0000 0000h −0.03125°C 1111 1111 1111 1000 FFF8h −1°C 1111 1111 0000 0000 FF00h −25°C 1110 0111 0000 0000 E700h −55°C 1100 1001 0000 0000 C900h Table 6. 13-Bit, Unsigned Binary Temperature Digital Output Binary Hex +255.875°C 1111 1111 1110 0000 FFE0h +255°C 1111 1111 0000 0000 FF00h +201°C 1100 1001 0000 0000 C900h +125°C 0111 1101 0000 0000 7D00h +25°C 0001 1001 0000 0000 1900h +1°C 0000 0001 0000 0000 0100h +0.03125°C 0000 0000 0000 1000 0008h 0°C 0000 0000 0000 0000 0000h Local Temperature data is represented by a 10-bit plus sign, two's complement word with an LSb (Least Significant Bit) equal to 0.125°C. The data format is a left justified 16-bit word available in two 8-bit registers. Unused bits will always report "0". Local temperature readings greater than +127.875°C are clamped to +127.875°C, they will not roll-over to negative temperature readings. Submit Documentation Feedback Copyright © 2007–2013, Texas Instruments Incorporated Product Folder Links: LM95245 13 LM95245 SNIS148G – OCTOBER 2007 – REVISED MARCH 2013 www.ti.com Table 7. 11-Bit, 2's Complement (10-Bit Plus Sign) Digital Output Temperature Binary Hex +125°C 0111 1101 0000 0000 7D00h +25°C 0001 1001 0000 0000 1900h +1°C 0000 0001 0000 0000 0100h +0.125°C 0000 0000 0010 0000 0020h 0°C 0000 0000 0000 0000 0000h −0.125°C 1111 1111 1110 0000 FFE0h −1°C 1111 1111 0000 0000 FF00h −25°C 1110 0111 0000 0000 E700h −55°C 1100 1001 0000 0000 C900h SMBDAT OPEN-DRAIN OUTPUT The SMBDAT output is an open-drain output and does not have internal pull-ups. A “high” level will not be observed on this pin until pull-up current is provided by some external source, typically a pull-up resistor. Choice of resistor value depends on many system factors but, in general, the pull-up resistor should be as large as possible without effecting the SMBus desired data rate. This will minimize any internal temperature reading errors due to internal heating of the LM95245. The maximum resistance of the pull-up to provide a 2.1V high level, based on LM95245 specification for High Level Output Current with the supply voltage at 3.0V, is 82 kΩ (5%) or 88.7 kΩ (1%). T_CRIT OUTPUT AND TCRIT LIMIT The LM95245's T_CRIT pin is an active-low open-drain output that is triggered when the local and/or the remote temperature conversion is above the limits defined by the Remote and/or Local Limit registers. The state of the T_CRIT pin will return to the HIGH state when both the Local and Remote temperatures are below the values programmed into the Limit Registers less the value in the Common Hysteresis Register. Additionally, if the remote temperature exceeds the value in the Remote TCRIT Limit Register the Status Bit for Remote TCRIT (RTCRIT), in Status Register 1, is set to 1. In the same way if the local temperature exceeds the value in the Local Shared OS and TCRIT Limit Register the Status Bit for the Shared Local OS and TCRIT (LOC) bit in Status Register 1 is set to 1.The T_CRIT output and the Status Register flags are updated after every Local and Remote temperature conversion. See Figure 12 Remote TCRIT Limit Hysteresis Remote TCRIT Limit Hysteresis Remote Temperature T_CRIT Output Pin Status bit RCRIT Figure 12. T_CRIT Comparator Temperature Response Diagram 14 Submit Documentation Feedback Copyright © 2007–2013, Texas Instruments Incorporated Product Folder Links: LM95245 LM95245 www.ti.com SNIS148G – OCTOBER 2007 – REVISED MARCH 2013 OS OUTPUT AND OS LIMIT The LM95245's OS/A0 pin is selected as an OS digital output as described in SMBus INTERFACE. As an OS pin, it is activated whenever the local and/or remote temperature conversion is above the limits defined by the Limit registers. If the remote temperature exceeds the value in the Remote OS Limit Register the Status Bit for Remote OS (ROS) in Status Register 1 is set to 1. In the same way if the local temperature exceeds the value in the Local Shared OS and TCRIT Limit Register the Status Bit for the Shared Local OS and TCRIT (LOC) bit in Status Register 1 is set to 1. The state of the T_CRIT pin output will return to the HIGH state when both the Local and Remote temperatures are below the values programmed into the Limit Registers less the value in the Common Hysteresis Register. The OS output and the Status Register flags are updated after every Local and Remote temperature conversion. See Figure 13. Remote OS Limit Hysteresis Remote Temperature Remote OS Limit Hysteresis OS Output Pin Status bit ROS Figure 13. OS Temperature Response Diagram DIODE FAULT DETECTION The LM95245 is equipped with operational circuitry designed to detect fault conditions concerning the remote diodes. In the event that the D+ pin is detected as shorted to GND, VDD or D+ is floating, the Remote Temperature reading is –128.000 °C if signed format is selected and +255.875 °C if unsigned format is selected. In addition, the Status Register 1 bit D2 is set. COMMUNICATING with the LM95245 SMBus Timing Diagrams for Access of Data (Default Address of 4Ch is Shown) 1 9 1 9 SMBCLK SMBDAT A6 A5 A4 A3 A2 A1 A0 R/W Start by Master D7 Ack by LM95245 D6 D5 Frame 1 Serial Bus Address Byte D4 D3 D2 Frame 2 Command Byte D1 D0 Ack by Stop LM95245 by Master Figure 14. (a) Serial Bus Write to the Internal Command Register Submit Documentation Feedback Copyright © 2007–2013, Texas Instruments Incorporated Product Folder Links: LM95245 15 LM95245 SNIS148G – OCTOBER 2007 – REVISED MARCH 2013 www.ti.com 1 9 1 9 SMBCLK SMBDAT A6 A5 A4 A3 A2 A1 A0 R/W D7 Ack by LM95245 Start by Master D6 D5 D4 Frame 1 Serial Bus Address Byte D3 D2 SMBDAT (Continued) D0 Ack by LM95245 Frame 2 Command Byte 1 SMBCLK (Continued) D1 9 D7 D6 D5 D4 D3 D2 D1 D0 Ack by Stop LM95245 by Master Frame 3 Data Byte Figure 15. (b) Serial Bus Write to the Internal Command Register Followed by a Data Byte 1 9 1 9 SMBCLK SMBDAT A6 A5 A4 A3 A2 A1 A0 R/W D7 Ack by LM95245 Start by Master D6 Frame 1 Serial Bus Address Byte D5 D4 D3 D2 D1 D0 NoAck Stop by by Master Master Frame 2 Data Byte from the LM95245 Figure 16. (c) Serial Bus byte Read from a Register with the Internal Command Register Preset to Desired Value 1 9 1 9 SMBCLK SMBDAT A6 A5 A4 A3 A2 A1 A0 R/W D7 Ack by LM95245 Start by Master D6 D5 Frame 1 Serial Bus Address Byte SMBCLK (Continued) SMBDAT (Continued) 9 A5 A4 A3 A2 A1 D3 D2 D1 D0 Ack Repeat by Start by LM95245 Master Frame 2 Command Byte 1 A6 D4 A0 R/W Frame 3 Serial Bus Address Byte 1 D7 Ack by LM95245 9 D6 D5 D4 D3 D2 D1 D0 Frame 4 Data Byte from the LM95245 No Ack Stop by by Master Master Figure 17. (d) Serial Bus Write followed by a Repeat Start and Immediate Read The data registers in the LM95245 are selected by the Command Register. At power-up the Command Register is set to “00”, the location for the Read Local Temperature Register. The Command Register latches the last location it was set to. Each data register in the LM95245 falls into one of four types of user accessibility: 1. Read only 2. Write only 16 Submit Documentation Feedback Copyright © 2007–2013, Texas Instruments Incorporated Product Folder Links: LM95245 LM95245 www.ti.com SNIS148G – OCTOBER 2007 – REVISED MARCH 2013 3. Write/Read same address 4. Write/Read different address A Write to the LM95245 will always include the address byte and the command byte. A write to any register requires one data byte. Reading the LM95245 can take place either of two ways: 1. If the location latched in the Command Register is correct (most of the time it is expected that the Command Register will point to one of the Read Temperature Registers because that will be the data most frequently read from the LM95245), then the read can simply consist of an address byte, followed by retrieving the data byte. 2. If the Command Register needs to be set, then an address byte, command byte, repeat start, and another address byte will accomplish a read. The data byte has the most significant bit first. At the end of a read, the LM95245 can accept either acknowledge or No Acknowledge from the Master (No Acknowledge is typically used as a signal for the slave that the Master has read its last byte). When retrieving all 11 bits from a previous remote diode temperature measurement, the master must insure that all 11 bits are from the same temperature conversion. This may be achieved by reading the MSB register first. The LSB will be locked after the MSB is read. The LSB will be unlocked after being read. If the user reads MSBs consecutively, each time the MSB is read, the LSB associated with that temperature will be locked in and override the previous LSB value locked-in. SERIAL INTERFACE RESET In the event that the SMBus Master is RESET while the LM95245 is transmitting on the SMBDAT line, the LM95245 must be returned to a known state in the communication protocol. This may be done in one of two ways: 1. When SMBDAT is LOW, the LM95245 SMBus state machine resets to the SMBus idle state if either SMBDAT or SMBCLK are held low for more than 35 ms (tTIMEOUT). Note that according to SMBus specification 2.0 all devices are to timeout when either the SMBCLK or SMBDAT lines are held low for 25 35 ms. Therefore, to insure a timeout of all devices on the bus the SMBCLK or SMBDAT lines must be held low for at least 35 ms. 2. When SMBDAT is HIGH, have the master initiate an SMBus start. The LM95245 will respond properly to an SMBus start condition at any point during the communication. After the start the LM95245 will expect an SMBus Address address byte. ONE-SHOT CONVERSION The One-Shot register is used to initiate a single conversion and comparison cycle when the device is in standby mode, after which the device returns to standby. This is not a data register and it is the write operation that causes the one-shot conversion. The data written to this address is irrelevant and is not stored. A zero will always be read from this register. Submit Documentation Feedback Copyright © 2007–2013, Texas Instruments Incorporated Product Folder Links: LM95245 17 LM95245 SNIS148G – OCTOBER 2007 – REVISED MARCH 2013 www.ti.com LM95245 REGISTERS Command register selects which registers will be read from or written to. Data for this register should be transmitted during the Command Byte of the SMBus write communication. POR means Power-On Reset. P0-P7: Command P7 P6 P5 P4 P3 P2 P1 P0 Command Table 8. Register Summary Register Name Read Address (Hex) Write Address (Hex) No. of bits POR Default (Hex) Read/ Write Description TEMPERATURE SIGNED VALUE REGISTERS Local Temp MSB 0x00 NA 8 − RO Supports SMBus byte Local Temp LSB 0x30 NA 3 − RO All unused bits are reported as "0". Remote Temp MSB – Signed 0x01 NA 8 − RO Supports SMBus byte Remote Temp LSB – Signed 0x10 NA 5/3 − RO All unused bits are reported as "0". TEMPERATURE UNSIGNED VALUE REGISTERS Remote Temp MSB – Unsigned 0x31 NA 8 − RO Supports SMBus byte reads Remote Temp LSB – Unsigned 0x32 NA 5/3 − RO All unused bits are reported as "0". DIODE CONFIGURATION REGISTERS Configuration Register 2 0xBF 0xBF 5 0x1F R/W Filter Enable, Diode Model Select, Diode Fault Mask; Pin 6 OS/A0 function select Remote Offset High Byte 0x11 0x11 8 0x00 R/W 2's Complement Remote Offset Low Byte 0x12 0x12 3 0x00 R/W 2's Complement All unused bits are reported as "0". 0x03/ 0x09 0x09/ 0x03 5 0x00 R/W STOP/RUN , Remote TCRIT mask, Remote OS mask, Local TCRIT mask, Local OS mask 0x04/0x0A 0x04/0x0A 2 0x02 R/W Continuous or specific settings NA 0x0F − − WO A write to this register activates one conversion if STOP/RUN bit = 1. Status Register 1 0x02 NA 5 − RO Busy bit, and status bits Status Register 2 0x33 NA 2 − RO Not Ready bit Remote OS Limit 0x07/ 0x0D 0x0D/ 0x07 8 0x55 R/W Unsigned 0 to 255 °C Default 85 °C Local Shared OS and T_Crit Limit 0x20 0x20 7 0x55 R/W Unsigned 0 to 127 °C Default 85 °C Remote T_Crit Limit 0x19 0x19 8 0x6E R/W Unsigned 0 to 255 °C Default 110 °C Common Hysteresis 0x21 0x21 5 0x0A R/W up to 31°C GENERAL CONFIGURATION REGISTERS Configuration Register 1 Conversion Rate One-Shot STATUS REGISTERS LIMIT REGISTERS IDENTIFICATION REGISTERS Manufacturer ID 0xFE 0x01 RO Always returns 0x01 Revision ID 0xFF 0xB3 RO Returns revision number. 18 Submit Documentation Feedback Copyright © 2007–2013, Texas Instruments Incorporated Product Folder Links: LM95245 LM95245 www.ti.com SNIS148G – OCTOBER 2007 – REVISED MARCH 2013 LOCAL and REMOTE MSB and LSB TEMPERATURE REGISTERS Table 9. Local Temperature MSB (Read Only Address 00h) 10-bit plus sign format: BIT Value D7 SIGN D6 64 D5 32 D4 16 D3 8 D2 4 D1 2 D0 1 D2 0 D1 0 D0 0 D2 4 D1 2 D0 1 Temperature Data: LSb = 1°C. Table 10. Local Temperature LSB (Read Only Address 30h) 10-bit plus sign format: BIT Value D7 0.5 D6 0.25 D5 0.125 D4 0 D3 0 Temperature Data: LSb = 0.125°C. Table 11. Signed Remote Temperature MSB (Read Only Address 01h) 12-bit plus sign format: BIT Value D7 SIGN D6 64 D5 32 D4 16 D3 8 Temperature Data: LSb = 1°C. Table 12. Signed Remote Temperature LSB, Filter On (Read Only Address 10h) 12-bit plus sign binary formats with filter on: BIT Value D7 0.5 D6 0.25 D5 0.125 D4 0.0625 D3 0.03125 D2 0 D1 0 D0 0 Table 13. Signed Remote Temperature LSB, Filter Off (Read Only Address 10h) 12-bit plus sign binary formats with filter off: BIT Value D7 0.5 D6 0.25 D5 0.125 D4 0 D3 0 D2 0 D1 0 D0 0 D2 4 D1 2 D0 1 Temperature Data: LSb = 0.125°C filter off or 0.03125°C filter on. Table 14. Unsigned Remote Temperature MSB (Read Only Address 31h) 13-bit unsigned format: BIT Value D7 128 D6 64 D5 32 D4 16 D3 8 Temperature Data: LSb = 1°C. Table 15. Unsigned Remote Temperature LSB, Filter On (Read Only Address 32h) 13-bit unsigned binary formats with filter on: BIT Value D7 0.5 D6 0.25 D5 0.125 D4 0.0625 D3 0.03125 D2 0 D1 0 Submit Documentation Feedback Copyright © 2007–2013, Texas Instruments Incorporated Product Folder Links: LM95245 D0 0 19 LM95245 SNIS148G – OCTOBER 2007 – REVISED MARCH 2013 www.ti.com Table 16. Unsigned Remote Temperature LSB, Filter Off (Read Only Address 32h) 13-bit unsigned binary formats with filter off: BIT Value D7 0.5 D6 0.25 D5 0.125 D4 0 D3 0 D2 0 D1 0 D0 0 Temperature Data: LSb = 0.125°C filter off or 0.03125°C filter on. For data synchronization purposes, the MSB register should be read first if the user wants to read both MSB and LSB registers. The LSB will be locked after the MSB is read. The LSB will be unlocked after being read. If the user reads MSBs consecutively, each time the MSB is read, the LSB associated with that temperature will be locked in and override the previous LSB value locked-in. DIODE CONFIGURATION REGISTERS Table 17. Configuration Register 2 (Read/write Address BFh): D7 0 D6 OS/A0 Function Select Bits 7 D5 OS Fault Mask Name Reserved 6 OS/A0 Function Select 5 Diode Fault Mask for OS 4 Diode Fault Mask for T_CRIT 3 Remote Diode TruTherm Mode Select 2-1 0 Remote Filter Enable Reserved D4 T_CRIT Mask D3 TruTherm Select D2 RFE1 D1 RFE0 D0 1 Description Reports "0" when read. 0: Address (A0) function is enabled 1: Over-temperature Shutdown (OS) is enabled 0: Off 1: On 0: Off 1: On 0: Selects Diode Model 2, MMBT3904, with TruTherm technology disabled. Note, performance in this mode is not guaranteed. 1: Selects Diode Model 1, A typical Intel Processor, with 45nm, 65 nm or 90 nm technology, and TruTherm technology enabled. 00: Filter Disable 01: Reserved 10: Reserved 11: Filter Enable Reports "1" when read. Power up default is 1Fh. Table 18. Remote Offset High Byte (2's Complement) (R/W Address 11h) 10-bit plus sign format: BIT Value D7 SIGN D6 64 D5 32 D4 16 D3 8 D2 4 D1 2 D0 1 D1 0 D0 0 Power up default is 00h. Table 19. Remote Offset Low Byte (2's Complement) (R/W Address 12h) 10-bit plus sign format: BIT Value D7 0.50 D6 0.25 D5 0.125 D4 0 D3 0 D2 0 Power up default is 00h. LSb = 0.125 °C. 20 Submit Documentation Feedback Copyright © 2007–2013, Texas Instruments Incorporated Product Folder Links: LM95245 LM95245 www.ti.com SNIS148G – OCTOBER 2007 – REVISED MARCH 2013 GENERAL CONFIGURATION REGISTERS Table 20. Configuration Register 1 (Read/write Address 03h/09h or 09h/03h): D7 0 D6 STOP/RUN Bits 7 D5 0 D4 Remote T_CRIT Mask D3 Remote OS Mask D2 Local T_CRIT Mask Name STOP/RUN 5 Reserved 4 Remote T_CRIT Mask 3 Remote OS Mask 2 Local T_CRIT Mask 1 Local OS Mask 0 Reserved D0 0 Description Reserved 6 D1 Local OS Mask Reports "0" when read. 0: Active / Converting 1: Standby Reports "0" when read. 0: Off 1: On 0: Off 1: On 0: Off 1: On 0: Off 1: On Reports "0" when read. Power up default is 00h. Table 21. Conversion Rate Register (Read/write Address 04h/0Ah or 0Ah/04h): 2-bit format: BIT Value D7 0 D6 0 Bits 7:2 Name Reserved 1:0 Conversion Rate D5 0 D4 0 D3 0 D2 0 D1 MSb D0 LSb Description Reports "0" when read. 00: Continuous (33 ms typical when remote diode is missing or fault or 63 ms typical with remote diode connected) 01: 0.364 seconds 10: 1 second 11: 2.5 seconds Power up default is 02h (1 second). Table 22. One Shot Register (Write Only Address 0Fh): Writing to this register will start one conversion if the device is in standby mode (i.e. STOP/RUN bit = 1). Submit Documentation Feedback Copyright © 2007–2013, Texas Instruments Incorporated Product Folder Links: LM95245 21 LM95245 SNIS148G – OCTOBER 2007 – REVISED MARCH 2013 www.ti.com STATUS REGISTERS Table 23. Status Register 1 (Read Only Address 02h): D7 Busy Bits 7 6-5 4 3 2 D6 0 D5 0 D4 ROS Name Busy Reserved ROS Reserved D2 Diode Fault D1 RTCRIT D0 LOC Description When set to "1" the part is converting. Report "0" when read. Status Bit for Remote OS Reports "0" when read. Status bit for missing diode (Either D+ is shorted to GND, or VDD; or D+ is floating.) Note: The unsigned registers will report 0°C if read; the signed value registers will report −128.000°C. Status bit for Remote TCRIT. Status bit for the shared Local OS and TCRIT . Diode Fault 1 0 D3 0 RTCRIT LOC Table 24. Status Register 2 (Read Only Address 33h): D7 Not Ready Bits 7 6 5-0 D6 Reserved Name D5 0 D4 0 D3 0 D2 0 D1 0 D0 0 Description Waiting for 30 ms power-up sequence to end. Can report "0" or "1" when read. Reports "0" when read. Not Ready Reserved Reserved LIMIT REGISTERS Table 25. Unsigned Remote OS Limit - 0°C to 255°C (Read/Write Address 07h/0Dh or 0Dh/07h): D7 128 D6 64 D5 32 D4 16 D3 8 D2 4 D1 2 D0 1 Power on Reset default is 55h (85°C). Table 26. Unsigned Local Shared OS and T_CRIT Limit - 0°C to 127°C (Read/Write Address 20h): D7 128 D6 64 D5 32 D4 16 D3 8 D2 4 D1 2 D0 1 D1 2 D0 1 Power on Reset default is 55h (85°C). Table 27. Unsigned Remote T_CRIT Limit - 0°C to 255°C (Read/Write Address 19h): D7 128 D6 64 D5 32 D4 16 D3 8 D2 4 Power on Reset default is 6Eh (110°C). 22 Submit Documentation Feedback Copyright © 2007–2013, Texas Instruments Incorporated Product Folder Links: LM95245 LM95245 www.ti.com SNIS148G – OCTOBER 2007 – REVISED MARCH 2013 Table 28. Common Hysteresis Register (Read/Write Address 21h): D7 0 D6 0 D5 0 D4 16 D3 8 D2 4 D1 2 D0 1 D2 0 D1 0 D0 1 Power on Reset default is 0Ah (10°C). IDENTIFICATION REGISTERS Table 29. Manufacturers ID Register (Read Only Address FEh): Always returns 01h. D7 0 D6 0 D5 0 D4 0 D3 0 Table 30. Revision ID Register (Read Only Address FFh) Default is B3h. This register will increment by 1 every time there is a revision to the die by Texas Instruments. The initial revision bits for B3h are shown below. D7 1 D6 0 D5 1 D4 1 D3 0 D2 0 D1 1 D0 1 Submit Documentation Feedback Copyright © 2007–2013, Texas Instruments Incorporated Product Folder Links: LM95245 23 LM95245 SNIS148G – OCTOBER 2007 – REVISED MARCH 2013 www.ti.com APPLICATIONS HINTS The LM95245 can be applied easily in the same way as other integrated-circuit temperature sensors, and its remote diode sensing capability allows it to be used in new ways as well. It can be soldered to a printed circuit board, and because the path of best thermal conductivity is between the die and the pins, its temperature will effectively be that of the printed circuit board lands and traces soldered to the LM95245's pins. This presumes that the ambient air temperature is almost the same as the surface temperature of the printed circuit board; if the air temperature is much higher or lower than the surface temperature, the actual temperature of the LM95245 die will be at an intermediate temperature between the surface and air temperatures. Again, the primary thermal conduction path is through the leads, so the circuit board temperature will contribute to the die temperature much more strongly than will the air temperature. To measure temperature external to the LM95245's die, use a remote diode. This diode can be located on the die of a target IC, allowing measurement of the IC's temperature, independent of the LM95245's temperature. A discrete diode can also be used to sense the temperature of external objects or ambient air. Remember that a discrete diode's temperature will be affected, and often dominated, by the temperature of its leads. Most silicon diodes do not lend themselves well to this application. It is recommended that an MMBT3904 transistor baseemitter junction be used with the collector tied to the base. Accuracy using the MMBT3904 is not guaranteed. For applications requiring the use of the MMBT3904 use the LM95235. The LM95245's BJT Beta Compensation TruTherm technology allows accurate sensing of integrated thermal diodes, such as those found on most processors. The LM95245 has been optimized to measure the remote thermal diode integrated in a typical Intel processor on 45 nm, 65 nm or 90 nm process. Using the Remote Diode Model Select register the remote inputs must be assigned to sense a typical Intel processor on 45nm, 65 nm or 90 nm process. The typical performance of the LM95245 with these processors is shown in Figure 18. The Remote Offset register can be used to compensate for temperature errors further. Figure 18. LM95245 Typical Performance with a Variety of Intel Processors DIODE NON-IDEALITY Diode Non-Ideality Factor Effect on Accuracy When a transistor is connected as a diode, the following relationship holds for variables VBE, T and IF: IF = IS x ª §KVxBEV · º «e© t¹ -1» « » ¬ ¼ where • 24 kT Vt = q Submit Documentation Feedback Copyright © 2007–2013, Texas Instruments Incorporated Product Folder Links: LM95245 LM95245 www.ti.com SNIS148G – OCTOBER 2007 – REVISED MARCH 2013 • • • • • • • q = 1.6×10−19 Coulombs (the electron charge), T = Absolute Temperature in Kelvin k = 1.38×10−23 joules/K (Boltzmann's constant), η is the non-ideality factor of the process the diode is manufactured on, IS = Saturation Current and is process dependent, If = Forward Current through the base-emitter junction VBE = Base-Emitter Voltage drop (1) In the active region, the -1 term is negligible and may be eliminated, yielding the following equation IF = IS x ª §KVxBEV ·º «e© t¹» « » ¬ ¼ (2) In Equation 2, η and IS are dependant upon the process that was used in the fabrication of the particular diode. By forcing two currents with a very controlled ratio(IF2 / IF1) and measuring the resulting voltage difference, it is possible to eliminate the IS term. Solving for the forward voltage difference yields the relationship: IF2 kT 'VBE = K x § q · x ln § I · F1 © ¹ © ¹ (3) Solving Equation 3 for temperature yields: q x 'VBE T= § IF2 · K x k x ln ¨¨ ¸ © IF1 ¹ (4) Equation 4 holds true when a diode connected transistor such as the MMBT3904 is used. When this “diode” equation is applied to an integrated diode such as a processor transistor with its collector tied to GND as shown in Figure 19 it will yield a wide non-ideality spread. This wide non-ideality spread is not due to true process variation but due to the fact that Equation 4 is an approximation. TruTherm technology uses the transistor (BJT) equation, Equation 5, which is a more accurate representation of the topology of the thermal diode found in an FPGA or processor. T= q x 'VBE §I · K x k x ln¨¨ C2 ¸ © IC1 ¹ (5) TruTherm should only be enabled when measuring the temperature of a transistor integrated as shown in the processor of Figure 19, because Equation 5 only applies to this topology. Submit Documentation Feedback Copyright © 2007–2013, Texas Instruments Incorporated Product Folder Links: LM95245 25 LM95245 SNIS148G – OCTOBER 2007 – REVISED MARCH 2013 www.ti.com 2 IE = IF D+ 100 pF 3 PROCESSOR IC IR D- LM95245 IF MMBT3904 2 D+ 100 pF 3 IR D- LM95245 Figure 19. Thermal Diode Current Paths Calculating Total System Accuracy The voltage seen by the LM95245 also includes the IFRS voltage drop of the series resistance. The non-ideality factor, η, is the only other parameter not accounted for and depends on the diode that is used for measurement. Since ΔVBE is proportional to both η and T, the variations in η cannot be distinguished from variations in temperature. Since the non-ideality factor is not controlled by the temperature sensor, it will directly add to the inaccuracy of the sensor. For the for Intel processor on 65nm process, Intel specifies a +4.06%/−0.897% variation in η from part to part when the processor diode is measured by a circuit that assumes diode equation, Equation 4, as true. As an example, assume a temperature sensor has an accuracy specification of ±1.0°C at a temperature of 80°C (353 Kelvin) and the processor diode has a non-ideality variation of +4.06%/−0.89%. The resulting system accuracy of the processor temperature being sensed will be: TACC = + 1.0°C + (+4.06% of 353 K) = +15.3 °C (6) TACC = - 1.0°C + (−0.89% of 353 K) = −4.1 °C (7) and TrueTherm technology uses the transistor equation, Equation 4, resulting in a non-ideality spread that truly reflects the process variation which is very small. The transistor equation non-ideality spread is ±0.39% for the 65nm thermal diode. The resulting accuracy when using TruTherm technology improves to: TACC = ±0.75°C + (±0.39% of 353 K) = ± 2.16 °C (8) Intel does not specify the diode model ideality and series resistance of the thermal diodes on 45nm so a similar comparison cannot be calculated, but lab experiments have shown similar improvement. For the 45nm processor the ideality spread as specified by Intel is -0.399% to +0.699%. The resulting spread in accuracy when using TruTherm technology with the thermal diode on Intel processors with 45nm process is: TACC = -0.75°C + (-0.39% of 353 K) = -2.16 °C (9) to TACC = +0.75°C + (+0.799% of 353 K) = +4.32 °C (10) The next error term to be discussed is that due to the series resistance of the thermal diode and printed circuit board traces. The thermal diode series resistance is specified on most processor data sheets. For Intel processors in 45 nm process, this is specified at 4.5Ω typical with a minimum of 3Ω and a maximum of 7Ω. The LM95245 accommodates the typical series resistance of Intel Processor on 45 nm process. The error that is not accounted for is the spread of the processor's series resistance. The equation used to calculate the temperature error due to series resistance (TER) for the LM95245 is simply: ºC · § TER = ¨0.62 : ¸ x RPCB © ¹ 26 (11) Submit Documentation Feedback Copyright © 2007–2013, Texas Instruments Incorporated Product Folder Links: LM95245 LM95245 www.ti.com SNIS148G – OCTOBER 2007 – REVISED MARCH 2013 Solving Equation 11 for RPCB equal to -1.5Ω to 2.5Ω results in the additional error due to the spread in this series resistance of -0.93°C to +1.55°C. The spread in error cannot be canceled out, as it would require measuring each individual thermal diode device. This is quite difficult and impractical in a large volume production environment. Equation 11 can also be used to calculate the additional error caused by series resistance on the printed circuit board. Since the variation of the PCB series resistance is minimal, the bulk of the error term is always positive and can simply be cancelled out by subtracting it from the output readings of the LM95245. Transistor Equation ηT, non-ideality Processor Family Series R,Ω min typ max Intel Processor on 45 nm process 0.997 1.001 1.008 4.5 Intel Processor on 65 nm process 0.997 1.001 1.005 4.52 Note: NA = Not Available at publication of this document. PCB LAYOUT FOR MINIMIZING NOISE Figure 20. Ideal Diode Trace Layout In a noisy environment, such as a processor mother board, layout considerations are very critical. Noise induced on traces running between the remote temperature diode sensor and the LM95245 can cause temperature conversion errors. Keep in mind that the signal level the LM95245 is trying to measure is in microvolts. The following guidelines should be followed: 1. 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. A bulk capacitance of approximately 10 µF needs to be in the near vicinity of the LM95245. 2. A 100 pF diode bypass capacitor is recommended to filter high frequency noise but may not be necessary. The LM95245 can handle capacitance up to 3.3 nF (see Typical Performance Curve "Remote Temperature Reading Sensitivity to Thermal Diode Filter Capacitance"). Place the filter capacitors close to the LM95245 pins and make sure the traces to this capacitor are matched. 3. Ideally, the LM95245 should be placed within 10 cm of the Processor diode pins with the traces being as straight, short and identical as possible. Trace resistance of 1Ω can cause as much as 0.62°C of error. This error can be compensated by using simple software offset compensation. 4. Diode traces should be surrounded by a GND guard ring to either side, above and below if possible. This GND guard should not be between the D+ and D− lines. In the event that noise does couple to the diode lines it would be ideal if it is coupled common mode. That is equally to the D+ and D− lines. 5. Avoid routing diode traces in close proximity to power supply switching or filtering inductors. 6. Avoid running diode traces close to or parallel to high speed digital and bus lines. Diode traces should be kept at least 2 cm apart from the high speed digital traces. 7. If it is necessary to cross high speed digital traces, the diode traces and the high speed digital traces should cross at a 90 degree angle. 8. The ideal place to connect the LM95245's GND pin is as close as possible to the Processors GND associated with the sense diode. 9. Leakage current between D+ and GND and between D+ and D− should be kept to a minimum. Thirteen nano-amperes of leakage can cause as much as 0.2°C of error in the diode temperature reading. Keeping the printed circuit board as clean as possible will minimize leakage current. Submit Documentation Feedback Copyright © 2007–2013, Texas Instruments Incorporated Product Folder Links: LM95245 27 LM95245 SNIS148G – OCTOBER 2007 – REVISED MARCH 2013 www.ti.com Noise coupling into the digital lines greater than 400 mVp-p (typical hysteresis) and undershoot less than 500 mV below GND, may prevent successful SMBus communication with the LM95245. SMBus no acknowledge is the most common symptom, causing unnecessary traffic on the bus. Although the SMBus maximum frequency of communication is rather low (100 kHz max), care still needs to be taken to ensure proper termination within a system with multiple parts on the bus and long printed circuit board traces. An RC lowpass filter with a 3 dB corner frequency of about 40 MHz is included on the LM95245's SMBCLK input. Additional resistance can be added in series with the SMBDAT and SMBCLK lines to further help filter noise and ringing. Minimize noise coupling by keeping digital traces out of switching power supply areas as well as ensuring that digital lines containing high speed data communications cross at right angles to the SMBDAT and SMBCLK lines. 28 Submit Documentation Feedback Copyright © 2007–2013, Texas Instruments Incorporated Product Folder Links: LM95245 LM95245 www.ti.com SNIS148G – OCTOBER 2007 – REVISED MARCH 2013 REVISION HISTORY Changes from Revision F (March 2013) to Revision G • Page Changed layout of National Data Sheet to TI format .......................................................................................................... 28 Submit Documentation Feedback Copyright © 2007–2013, Texas Instruments Incorporated Product Folder Links: LM95245 29 PACKAGE OPTION ADDENDUM www.ti.com 1-Nov-2013 PACKAGING INFORMATION Orderable Device Status (1) LM95245CIM/NOPB Package Type Package Pins Package Drawing Qty ACTIVE SOIC D 8 95 Eco Plan Lead/Ball Finish MSL Peak Temp (2) (6) (3) Green (RoHS & no Sb/Br) CU SN Level-1-260C-UNLIM Op Temp (°C) Device Marking (4/5) 95245 CIM LM95245CIMM NRND VSSOP DGK 8 1000 TBD Call TI Call TI -40 to 125 T45C LM95245CIMM-1/NOPB ACTIVE VSSOP DGK 8 1000 Green (RoHS & no Sb/Br) CU SN Level-1-260C-UNLIM -40 to 125 T46C LM95245CIMM/NOPB ACTIVE VSSOP DGK 8 1000 Green (RoHS & no Sb/Br) CU SN Level-1-260C-UNLIM -40 to 125 T45C LM95245CIMMX-1/NOPB ACTIVE VSSOP DGK 8 3500 Green (RoHS & no Sb/Br) CU SN Level-1-260C-UNLIM -40 to 125 T46C LM95245CIMMX/NOPB ACTIVE VSSOP DGK 8 3500 Green (RoHS & no Sb/Br) CU SN Level-1-260C-UNLIM -40 to 125 T45C LM95245CIMX/NOPB ACTIVE SOIC D 8 2500 Green (RoHS & no Sb/Br) CU SN Level-1-260C-UNLIM 95245 CIM (1) The marketing status values are defined as follows: ACTIVE: Product device recommended for new designs. LIFEBUY: TI has announced that the device will be discontinued, and a lifetime-buy period is in effect. NRND: Not recommended for new designs. Device is in production to support existing customers, but TI does not recommend using this part in a new design. PREVIEW: Device has been announced but is not in production. Samples may or may not be available. OBSOLETE: TI has discontinued the production of the device. (2) Eco Plan - The planned eco-friendly classification: Pb-Free (RoHS), Pb-Free (RoHS Exempt), or Green (RoHS & no Sb/Br) - please check http://www.ti.com/productcontent for the latest availability information and additional product content details. TBD: The Pb-Free/Green conversion plan has not been defined. Pb-Free (RoHS): TI's terms "Lead-Free" or "Pb-Free" mean semiconductor products that are compatible with the current RoHS requirements for all 6 substances, including the requirement that lead not exceed 0.1% by weight in homogeneous materials. Where designed to be soldered at high temperatures, TI Pb-Free products are suitable for use in specified lead-free processes. Pb-Free (RoHS Exempt): This component has a RoHS exemption for either 1) lead-based flip-chip solder bumps used between the die and package, or 2) lead-based die adhesive used between the die and leadframe. The component is otherwise considered Pb-Free (RoHS compatible) as defined above. Green (RoHS & no Sb/Br): TI defines "Green" to mean Pb-Free (RoHS compatible), and free of Bromine (Br) and Antimony (Sb) based flame retardants (Br or Sb do not exceed 0.1% by weight in homogeneous material) (3) MSL, Peak Temp. - The Moisture Sensitivity Level rating according to the JEDEC industry standard classifications, and peak solder temperature. (4) There may be additional marking, which relates to the logo, the lot trace code information, or the environmental category on the device. Addendum-Page 1 Samples PACKAGE OPTION ADDENDUM www.ti.com 1-Nov-2013 (5) Multiple Device Markings will be inside parentheses. Only one Device Marking contained in parentheses and separated by a "~" will appear on a device. If a line is indented then it is a continuation of the previous line and the two combined represent the entire Device Marking for that device. (6) Lead/Ball Finish - Orderable Devices may have multiple material finish options. Finish options are separated by a vertical ruled line. Lead/Ball Finish values may wrap to two lines if the finish value exceeds the maximum column width. Important Information and Disclaimer:The information provided on this page represents TI's knowledge and belief as of the date that it is provided. TI bases its knowledge and belief on information provided by third parties, and makes no representation or warranty as to the accuracy of such information. Efforts are underway to better integrate information from third parties. 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Addendum-Page 2 PACKAGE MATERIALS INFORMATION www.ti.com 23-Sep-2013 TAPE AND REEL INFORMATION *All dimensions are nominal Device Package Package Pins Type Drawing SPQ Reel Reel A0 Diameter Width (mm) (mm) W1 (mm) B0 (mm) K0 (mm) P1 (mm) W Pin1 (mm) Quadrant LM95245CIMM VSSOP DGK 8 1000 178.0 12.4 5.3 3.4 1.4 8.0 12.0 Q1 LM95245CIMM-1/NOPB VSSOP DGK 8 1000 178.0 12.4 5.3 3.4 1.4 8.0 12.0 Q1 LM95245CIMM/NOPB VSSOP DGK 8 1000 178.0 12.4 5.3 3.4 1.4 8.0 12.0 Q1 LM95245CIMMX-1/NOPB VSSOP DGK 8 3500 330.0 12.4 5.3 3.4 1.4 8.0 12.0 Q1 LM95245CIMMX/NOPB VSSOP DGK 8 3500 330.0 12.4 5.3 3.4 1.4 8.0 12.0 Q1 LM95245CIMX/NOPB SOIC D 8 2500 330.0 12.4 6.5 5.4 2.0 8.0 12.0 Q1 Pack Materials-Page 1 PACKAGE MATERIALS INFORMATION www.ti.com 23-Sep-2013 *All dimensions are nominal Device Package Type Package Drawing Pins SPQ Length (mm) Width (mm) Height (mm) LM95245CIMM VSSOP DGK 8 1000 210.0 185.0 35.0 LM95245CIMM-1/NOPB VSSOP DGK 8 1000 210.0 185.0 35.0 LM95245CIMM/NOPB VSSOP DGK 8 1000 210.0 185.0 35.0 LM95245CIMMX-1/NOPB VSSOP DGK 8 3500 367.0 367.0 35.0 LM95245CIMMX/NOPB VSSOP DGK 8 3500 367.0 367.0 35.0 LM95245CIMX/NOPB SOIC D 8 2500 367.0 367.0 35.0 Pack Materials-Page 2 IMPORTANT NOTICE Texas Instruments Incorporated and its subsidiaries (TI) reserve the right to make corrections, enhancements, improvements and other changes to its semiconductor products and services per JESD46, latest issue, and to discontinue any product or service per JESD48, latest issue. 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