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LM95241

www.ti.com

SNIS143E –AUGUST 2006–REVISED MARCH 2013

LM95241 Dual Remote Diode Temperature Sensor with SMBus Interface and TruTherm™

Technology (65nm/90nm)

Check for Samples: LM95241

FEATURES

KEY SPECIFICATIONS

• Accurately Senses Die Temperature of Remote

• Remote Diode Temperature Accuracy

ICs or Diode Junctions

– T

= 20°C to 40°C, T

= 45°C to 85°C ±1.25

• Uses TruTherm Technology for Precision °C (Max)

“Thermal Diode” Temperature Measurement

– T

= 0°C to 85°C, T

= 25°C to 140°C ±2.5 °C

• Thermal Diode Input Stage with Analog (Max)

Filtering

• Local Temperature Accuracy

• Thermal Diode Digital Filtering

– T

= 0°C to 85°C ±3.0 °C (Max)

• Intel Processor on 65nm or 90nm Process or

• Supply Voltage 3.0 V to 3.6 V

2N3904 Non-Ideality Selection

• Average Supply Current 471 μA (Typ)

• Remote Diode Fault Detection

• On-board Local Temperature Sensing APPLICATIONS

• Remote Temperature Readings Without Digital

• Processor/Computer System Thermal

Filtering:

Management

– 0.125 °C LSb

– (e.g. Laptop, Desktop, Workstations,

Server)

– 10-bits Plus Sign or 11-bits Programmable

Resolution

• Electronic Test Equipment

– 11-bits Resolves Temperatures Above

• Office Electronics

127 °C

DESCRIPTION

• Remote Temperature Readings with Digital

Filtering:

The LM95241 is a precision dual remote diode

temperature sensor (RDTS) that uses TI's TruTherm

– 0.03125 °C LSb with Filtering

technology. The 2-wire serial interface of the

– 12-bits Plus Sign or 13-bits Programmable

LM95241 is compatible with SMBus 2.0. The

Resolution

LM95241 can sense three temperature zones, it can

– 13-bits Resolves Temperatures Above

measure the temperature of its own die as well as

two diode connected transistors. The LM95241

127 °C

includes digital filtering and an advanced input stage

• Local Temperature Readings:

that includes analog filtering and TruTherm

– 0.25 °C

technology that reduces processor-to-processor non-

– 9-bits Plus Sign

ideality spread. The diode connected transistors can

be a “thermal diode” as found in Intel and AMD

• Status Register Support

processors or can simply be a diode connected

• Programmable Conversion Rate Allows User

MMBT3904 transistor. TruTherm technology allows

Optimization of Power Consumption

accurate measurement of “thermal diodes” found on

• Shutdown Mode One-shot Conversion Control

small geometry processes such as 90nm and 65nm.

The LM95241 supports user selectable thermal diode

• SMBus 2.0 Compatible Interface, Supports

non-ideality of either Intel processor on 90nm or

TIMEOUT

65nm process or 2N3904.

• 8-pin VSSOP Package

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 (29 pages)

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LM95241 www.ti.
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LM95241 SNIS143E – AUGUST 2006 – REVISED MARCH 2013 www.ti.com DESCRIPTION (CONTINUED) The LM95241 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 LM95241 remote diode readings can resolve temperatures above 127°C. Local temperature readings have a resolution of 9-bits plus sign.
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LM95241 www.ti.com SNIS143E – AUGUST 2006 – REVISED MARCH 2013 Simplified Block Diagram 3.0V-3.
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LM95241 SNIS143E – AUGUST 2006 – REVISED MARCH 2013 www.ti.com Absolute Maximum Ratings (1) −0.3 V to 6.0 V Supply Voltage −0.5V to 6.0V Voltage at SMBDAT, SMBCLK −0.3 V to (VDD + 0.
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LM95241 www.ti.com SNIS143E – AUGUST 2006 – REVISED MARCH 2013 Temperature-to-Digital Converter Characteristics Unless otherwise noted, these specifications apply for VDD=+3.0Vdc to 3.6Vdc. 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 LM95241. TD is the junction temperature of the remote thermal diode.
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LM95241 SNIS143E – AUGUST 2006 – REVISED MARCH 2013 www.ti.com Logic Electrical Characteristics Digital DC Characteristics Unless otherwise noted, these specifications apply for VDD=+3.0 to 3.6 Vdc. Boldface limits apply for TA = TJ = TMIN to TMAX; all other limits TA= TJ=+25°C, unless otherwise noted. Symbol Parameter Conditions Typical (1) Limits (2) Units (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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LM95241 www.ti.com SNIS143E – AUGUST 2006 – REVISED MARCH 2013 Logic Electrical Characteristics SMBus Digital Switching Characteristics (continued) 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 LM95241 fully meet or exceed the published specifications of the SMBus version 2.0.
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LM95241 SNIS143E – AUGUST 2006 – REVISED MARCH 2013 www.ti.com Typical Performance Characteristics 8 Intel Processor on 65nm Process or 90nm Process Thermal Diode Performance Comparison Thermal Diode Capacitor or PCB Leakage Current Effect Remote Diode Temperature Reading Figure 3. Figure 4. Remote Temperature Reading Sensitivity to Thermal Diode Filter Capacitance Conversion Rate Effect on Average Power Supply Current Figure 5. Figure 6.
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LM95241 www.ti.com SNIS143E – AUGUST 2006 – REVISED MARCH 2013 FUNCTIONAL DESCRIPTION The LM95241 is a digital sensor that can sense the temperature of 3 thermal zones using a sigma-delta analogto-digital converter. It can measure its local die temperature and the temperature of two external transistor junctions using a ΔVbe temperature sensing method. The LM95241 can support two external transistor types, a Intel processor on 65nm or 90mn process thermal diode or a 2N3904 diode connected transistor.
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LM95241 SNIS143E – AUGUST 2006 – REVISED MARCH 2013 www.ti.com CONVERSION SEQUENCE In the power up default state the LM95241 typically takes 77.8 ms to convert the Local Temperature, Remote Temperature 1 and 2, and to update all of its registers. Only during the conversion process is the busy bit (D7) in the Status register (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 Configuration Register (03h).
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LM95241 www.ti.com SNIS143E – AUGUST 2006 – REVISED MARCH 2013 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 11-bit, two's complement word or 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 will always report "0". Table 2.
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LM95241 SNIS143E – AUGUST 2006 – REVISED MARCH 2013 www.ti.com Table 5. 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.
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LM95241 www.ti.com SNIS143E – AUGUST 2006 – REVISED MARCH 2013 A Write to the LM95241 will always include the address byte and the command byte. A write to any register requires one data byte. Reading the LM95241 can take place either of two ways: 1.
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LM95241 SNIS143E – AUGUST 2006 – REVISED MARCH 2013 www.ti.com 1 9 1 9 SMBCLK SMBDAT A6 A4 A5 A3 A2 A1 A0 D7 R/W D6 D5 D4 D3 D2 D1 D0 Ack by LM95241 Start by Master NoAck Stop by by Master Master Frame 1 Serial Bus Address Byte Frame 2 Data Byte from the LM95241 Figure 10. Serial Bus byte Read from a Register with the internal Command Register preset to desired value.
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LM95241 www.ti.com SNIS143E – AUGUST 2006 – REVISED MARCH 2013 P7 P6 P5 P4 P3 P2 P1 P0 Command P0-P7: Command Table 6.
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LM95241 SNIS143E – AUGUST 2006 – REVISED MARCH 2013 www.ti.com Bits Name Description 0 Remote Diode 1 Missing (RD1M) When set to "1" Remote Diode 1 is missing. (See DIODE FAULT DETECTION for further details.) Temperature Reading is FFE0h which converts to 255.875 °C if unsigned format is selected or 8000h which converts to –128.000 °C if signed format is selected. Note, connecting a 3904 transistor to Remote 1 inputs with TruTherm mode active may also cause this bit to be set.
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LM95241 www.ti.com SNIS143E – AUGUST 2006 – REVISED MARCH 2013 Bits Name Description 7-3 Reserved Reports "0" when read. 2 Remote Diode 2 Model Select (R2MS) 0: 2N3904 model (make sure TruTherm mode is disabled) 1: Intel processor on 65nm or 90nm process model (make sure TruTherm mode is enabled) Power up default is 0. 1 Reserved Reports "0" when read.
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LM95241 SNIS143E – AUGUST 2006 – REVISED MARCH 2013 www.ti.com Remote Temperature MSB (Read Only Address 11h, 12h) 10-bit plus sign format: BIT D7 D6 D5 D4 D3 D2 D1 D0 Value SIGN 64 32 16 8 4 2 1 Temperature Data: LSb = 1°C. Remote Temperature MSB (Read Only Address 11h, 12h) 11-bit plus sign format: BIT D7 D6 D5 D4 D3 D2 D1 D0 Value 128 64 32 16 8 4 2 1 Temperature Data: LSb = 1°C.
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LM95241 www.ti.com SNIS143E – AUGUST 2006 – REVISED MARCH 2013 To measure temperature external to the LM95241'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 LM95241'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.
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LM95241 SNIS143E – AUGUST 2006 – REVISED MARCH 2013 T= www.ti.com 'VBE x q IC2 K x k x ln IC1 (5) 65nm/90nm PROCESSOR IE = IF 100 pF 1 2 3 IC IR 100 pF 4 D1+ D1D2+ D2- LM95241 IF Q1 MMBT3904 IR Figure 12. Thermal Diode Current Paths TruTherm should only be enabled when measuring the temperature of a transistor integrated as shown in the processor of Figure 12, because Equation 5 only applies to this topology.
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LM95241 www.ti.com SNIS143E – AUGUST 2006 – REVISED MARCH 2013 Diode Equation ηD, non-ideality Processor Family Pentium III CPUID 67h Series R min typ max 1 1.0065 1.0125 Pentium III CPUID 68h/PGA370Socket/ Celeron 1.0057 1.008 1.0125 Pentium 4, 423 pin 0.9933 1.0045 1.0368 Pentium 4, 478 pin 0.9933 1.0045 1.0368 Pentium 4 on 0.13 micron process, 2-3.06GHz 1.0011 1.0021 1.0030 3.64 Ω Pentium 4 on 90 nm process 1.0083 1.011 1.023 3.
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LM95241 SNIS143E – AUGUST 2006 – REVISED MARCH 2013 www.ti.com PCB LAYOUT FOR MINIMIZING NOISE Figure 13. 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 LM95241 can cause temperature conversion errors. Keep in mind that the signal level the LM95241 is trying to measure is in microvolts. The following guidelines should be followed: 1.
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LM95241 www.ti.com SNIS143E – AUGUST 2006 – REVISED MARCH 2013 REVISION HISTORY Changes from Revision D (March 2013) to Revision E • 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 7-Oct-2013 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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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 LM95241CIMM-1/NOPB VSSOP DGK 8 1000 178.0 12.4 5.3 3.4 1.4 8.0 12.0 Q1 LM95241CIMM-2/NOPB VSSOP DGK 8 1000 178.0 12.4 5.3 3.4 1.4 8.0 12.0 Q1 LM95241CIMM/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) LM95241CIMM-1/NOPB VSSOP DGK 8 1000 210.0 185.0 35.0 LM95241CIMM-2/NOPB VSSOP DGK 8 1000 210.0 185.0 35.0 LM95241CIMM/NOPB VSSOP DGK 8 1000 210.0 185.0 35.0 LM95241CIMMX-1/NOPB VSSOP DGK 8 3500 367.0 367.0 35.0 LM95241CIMMX-2/NOPB VSSOP DGK 8 3500 367.0 367.0 35.
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