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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

• Remote and Local Temperature Channels

with a 2-wire System Management Bus (SMBus)

• Targeted for Intel 45nm Processor Diodes

interface and TruTherm technology that can monitor

• Two Formats: −128°C to +127.875°C and 0°C to

the temperature of a remote diode as well as its own

255.875°C

temperature. The LM95245 can be used to very

accurately monitor the temperature of external

• Digital Filter for Remote Channel

devices such as microprocessors. TruTherm

• Programmable TCRIT and OS Thresholds

technology allows the LM95245 to precisely monitor

• Programmable Shared Hysteresis Register

thermal diodes found in 90 nm and smaller geometry

processes. The LM95245 is specifically targeted for

• Diode Fault Detection

Intel processors on 45nm process. LM95245 reports

• Mask, Offset, and Status Registers

temperature in two different formats for +127.875°C/-

• SMBus 2.0 Compatible Interface, Supports

128°C range and 0°C/255°C range. The LM95245

TIMEOUT

T_CRIT and OS outputs are asserted when either

unmasked channel exceeds its programmed limit and

• Programmable Conversion Rate for Best

can be used to shutdown the system, to turn on the

Power Consumption

system fans, or as a microcontroller interrupt function.

• Three-Level Address Pin

The current status of the T_CRIT and OS pins can be

• Standby Mode One-Shot Conversion Control

read back from the status registers via the SMBus

interface. All limits have a shared programmable

• Pin-for-Pin Compatible With the LM95235 and

hysteresis register.

LM86, LM89, LM99

The remote temperature channel of the LM95245 has

• 8-Pin VSSOP and SOIC Packages

a programmable digital filter. The LM95245 is

targeted for a typical Intel® processor on a 45 nm, 65

APPLICATIONS

nm or 90nm process, and has an offset register for

• Processor/Computer System Thermal

maximum flexibility and best accuracy.

Management (For Example, Laptops,

The LM95245 has a three-level address pin to

Desktops, Workstations, Servers)

connect up to 3 devices to the same SMBus master,

• Electronic Test Equipment

that is shared with the OS output. The LM95245 has

• Office Electronics 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

KEY SPECIFICATIONS

• Supply Voltage 3.0 to 3.6 V

• Supply Current, Conv. Rate = 1 Hz 350 µA (typ)

• Remote Diode Temperature Accuracy

– T

= 25°C to 85°C; T

= 50°C to 105°C, ±0.75

°C (max)

– T

= 25°C to 85°C; T

= 40°C to 125°C, ±1.5

°C (max)

• Local Temperature Accuracy

– T

= 25°C to 100°C, ±2.0 °C (max)

• Conversion Rate, Both Channels 16 to 0.4 Hz

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.

2All 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.

Summary of content (36 pages)

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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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).
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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 ..........................................................................................................
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PACKAGE OPTION ADDENDUM www.ti.
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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.
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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.
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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.
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