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LM95235

LM95235-Q1

www.ti.com

SNIS142F –APRIL 2006–REVISED MARCH 2013

Precision Remote Diode Temperature Sensor with SMBus Interface and TruTherm™

Technology

Check for Samples: LM95235, LM95235-Q1

FEATURES

KEY SPECIFICATIONS

• Remote and Local Temperature Channels

• Supply Voltage 3.0 to 3.6 V

• TruTherm BJT Beta Compensation Technology • Supply Current, Conv. Rate = 1 Hz 350 µA (typ)

• LM95235Q is AEC-Q100 Grade 3 Compliant • Remote Diode Temperature Accuracy

and is Manufactured on an Automotive Grade

– T

= 25°C to 85°C; T

= 60°C to 100°C, ±0.75

Flow

°C (max)

• Diode Model Selection Bit - MMBT3904 or

– T

= 25°C to 90°C; T

= 40°C to 125°C, ±1.5

65/90-nm Processor Diodes

°C (max)

• Two Formats: -128°C to 127.875°C and 0°C to

• Local Temperature Accuracy

255.875°C

– T

= 25°C to 100°C, ±2.0 °C (max)

• Digital Filter for Remote Channel

• Conversion Rate, Both Channels 16 to 0.4 Hz

• Programmable TCRIT and OS Thresholds

• Programmable Shared Hysteresis Register DESCRIPTION

The LM95235 is an 11-bit digital temperature sensor

• Diode Fault Detection

with a 2-wire System Management Bus (SMBus)

• Mask, Offset, and Status Registers

interface and TruTherm technology that can monitor

• SMBus 2.0 Compatible Interface, Supports

the temperature of a remote diode as well as its own

TIMEOUT

temperature. The LM95235 can be used to very

accurately monitor the temperature of external

• Programmable Conversion Rate for Best

devices such as microprocessors, graphics

Power Consumption

processors, or a diode-connected MMBT3904

• Three-Level Address Pin

transistor. For automotive applications the LM95235Q

• Standby Mode One-Shot Conversion Control

is available that is AEC-Q100 Grade3 compliant and

is manufactured on an Automotive Grade Flow.

• Pin-for-Pin Compatible With the LM86 and

TruTherm BJT (transistor) beta compensation

LM89

technology allows the LM95235 to precisely monitor

• 8-Pin VSSOP Package

thermal diodes found in 90 nm and smaller geometry

processes. LM95235 reports temperature in two

APPLICATIONS

different formats for +127.875°C/-128°C range and

0°C/255°C range. The LM95235 T_CRIT and OS

• Processor/Computer System Thermal

outputs are asserted when either unmasked channel

Management (For Example, Laptops,

exceeds its programmed limit and can be used to

Desktops, Workstations, Servers)

shutdown the system, to turn on the system fans, or

• Electronic Test Equipment and Office

as a microcontroller interrupt function. The current

Electronics

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

The remote temperature channel of the LM95235 has

a programmable digital filter. The LM95235 contains

a diode model selection bit to select between a

typical Intel® processor on a 65 nm or 90 nm process

or MMBT3904, as well as an offset register for

maximum flexibility and best accuracy.

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 (35 pages)

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LM95235 LM95235-Q1 www.ti.
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LM95235 LM95235-Q1 SNIS142F – APRIL 2006 – REVISED MARCH 2013 www.ti.com DESCRIPTION (CONTINUED) The LM95235 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 LM95235 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.
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LM95235 LM95235-Q1 www.ti.com SNIS142F – APRIL 2006 – REVISED MARCH 2013 Table 1. Pin Descriptions Pin Number Name Type Description 1 VDD Power 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. 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 Critical temperature output.
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LM95235 LM95235-Q1 SNIS142F – APRIL 2006 – 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. Absolute Maximum Ratings (1) 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 Input Current at D- Pin (VDD +0.
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LM95235 LM95235-Q1 www.ti.com SNIS142F – APRIL 2006 – REVISED MARCH 2013 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 LM95235. TA is the ambient temperature of the LM95235. TD is the junction temperature of the remote thermal diode.
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LM95235 LM95235-Q1 SNIS142F – APRIL 2006 – 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. Symbol Parameter Typical (1) Test Conditions 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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LM95235 LM95235-Q1 www.ti.com SNIS142F – APRIL 2006 – REVISED MARCH 2013 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 LM95235 fully meet or exceed the published specifications of the SMBus version 2.0.
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LM95235 LM95235-Q1 SNIS142F – APRIL 2006 – 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 65nm Process or 90nm Process Thermal Diode Performance Comparison Figure 5. Figure 6.
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LM95235 LM95235-Q1 www.ti.com SNIS142F – APRIL 2006 – REVISED MARCH 2013 FUNCTIONAL DESCRIPTION The LM95235 is a temperature sensor that measures Local and Remote temperature zones. The LM95235 uses a ΔVbe temperature sensing method. A differential voltage, representing temperature, is digitized using a SigmaDelta analog to digital converter. TruTherm Technology allows the LM95235 to accurately sense the temperature of a thermal diode found on die fabricated using a sub-micron process.
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LM95235 LM95235-Q1 SNIS142F – APRIL 2006 – REVISED MARCH 2013 www.ti.com CONVERSION SEQUENCE In the power-up default state the LM95235 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.
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LM95235 LM95235-Q1 www.ti.com SNIS142F – APRIL 2006 – REVISED MARCH 2013 Table 3. Address Selection SMBus Device Address State of the A0 Pin HEX Binary Low 18 001 1000 Mid-Supply 29 010 1001 High 4C 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.
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LM95235 LM95235-Q1 SNIS142F – APRIL 2006 – REVISED MARCH 2013 www.ti.com Figure 10. Filter Impulse and Step Response Curve Impulse Response with Input Transients Greater Than 4°C Figure 11 shows the filter in use in a typical Intel processor on a 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.
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LM95235 LM95235-Q1 www.ti.com SNIS142F – APRIL 2006 – REVISED MARCH 2013 Table 4. 11-Bit, 2's Complement (10-Bit Plus Sign) (continued) Temperature Digital Output Binary Hex FF00h -1°C 1111 1111 0000 0000 -25°C 1110 0111 0000 0000 E700h -55°C 1100 1001 0000 0000 C900h Table 5. 11-Bit, Unsigned Binary Temperature Digital Output Binary Hex +255.
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LM95235 LM95235-Q1 SNIS142F – APRIL 2006 – REVISED MARCH 2013 www.ti.com Table 8. 11-Bit, 2's Complement (10-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 +0.125°C 0000 0000 0010 0000 0020h 0°C 0000 0000 0000 0000 0000h -0.
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LM95235 LM95235-Q1 www.ti.com SNIS142F – APRIL 2006 – REVISED MARCH 2013 OS OUTPUT AND OS LIMIT The LM95235'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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LM95235 LM95235-Q1 SNIS142F – APRIL 2006 – REVISED MARCH 2013 www.ti.com The data byte has the most significant bit first. At the end of a read, the LM95235 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.
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LM95235 LM95235-Q1 www.ti.
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LM95235 LM95235-Q1 SNIS142F – APRIL 2006 – REVISED MARCH 2013 www.ti.com LM95235 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 9. Register Summary Register Name Read Address (Hex) Write Address (Hex) No.
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LM95235 LM95235-Q1 www.ti.com SNIS142F – APRIL 2006 – REVISED MARCH 2013 LOCAL and REMOTE MSB and LSB TEMPERATURE REGISTERS Table 10. 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 11. 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 12.
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LM95235 LM95235-Q1 SNIS142F – APRIL 2006 – REVISED MARCH 2013 www.ti.com Table 17. 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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LM95235 LM95235-Q1 www.ti.com SNIS142F – APRIL 2006 – REVISED MARCH 2013 GENERAL CONFIGURATION REGISTERS Table 21. 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 Name Reserved 6 STOP/RUN 5 Reserved 4 Remote T_CRIT Mask 3 Remote OS Mask 2 Local T_CRIT Mask 1 Local OS Mask 0 Reserved D2 Local T_CRIT Mask D1 Local OS Mask D0 0 Description Reports "0" when read.
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LM95235 LM95235-Q1 SNIS142F – APRIL 2006 – REVISED MARCH 2013 www.ti.com STATUS REGISTERS Table 24. Status Register 1 (Read Only Address 02h): D7 Busy Bits 7 6-5 4 3 2 D6 0 D5 0 Name Busy Reserved ROS Reserved D3 0 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, and/or VDD, and/or D-; or D+ is floating.
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LM95235 LM95235-Q1 www.ti.com SNIS142F – APRIL 2006 – REVISED MARCH 2013 Table 29. 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 30. Manufacturers ID Register (Read Only Address FEh): Always returns 01h. D7 0 D6 0 D5 0 D4 0 D3 0 Table 31. Revision ID Register (Read Only Address FFh): Default is B1h.
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LM95235 LM95235-Q1 SNIS142F – APRIL 2006 – REVISED MARCH 2013 www.ti.com APPLICATIONS HINTS The LM95235 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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LM95235 LM95235-Q1 www.ti.com SNIS142F – APRIL 2006 – REVISED MARCH 2013 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 18 it will yield a wide non-ideality spread.
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LM95235 LM95235-Q1 SNIS142F – APRIL 2006 – REVISED MARCH 2013 www.ti.com TrueTherm technology uses the transistor equation, Equation 5, 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 Pentium 4 processor on 90 nm process. The resulting accuracy when using TruTherm technology improves to: TACC = ±0.75°C + (±0.39% of 353 K) = ± 2.
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LM95235 LM95235-Q1 www.ti.com SNIS142F – APRIL 2006 – REVISED MARCH 2013 Temperature errors associated with non-ideality of different processor types may be reduced in a specific temperature range of concern through use of software calibration. Typical Non-ideality specification differences cause a gain variation of the transfer function, therefore the center of the temperature range of interest should be the target temperature for calibration purposes.
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LM95235 LM95235-Q1 SNIS142F – APRIL 2006 – REVISED MARCH 2013 www.ti.com 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 LM95235'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.
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LM95235 LM95235-Q1 www.ti.com SNIS142F – APRIL 2006 – REVISED MARCH 2013 REVISION HISTORY Changes from Revision E (March 2013) to Revision F • 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 (4) 1-Nov-2013 There may be additional marking, which relates to the logo, the lot trace code information, or the environmental category on the device. (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.
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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 LM95235CIMM/NOPB VSSOP DGK 8 1000 178.0 12.4 5.3 3.4 1.4 8.0 12.0 Q1 LM95235CIMMX/NOPB VSSOP DGK 8 3500 330.0 12.4 5.3 3.4 1.4 8.0 12.0 Q1 LM95235DIMM/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) LM95235CIMM/NOPB VSSOP DGK 8 1000 210.0 185.0 35.0 LM95235CIMMX/NOPB VSSOP DGK 8 3500 367.0 367.0 35.0 LM95235DIMM/NOPB VSSOP DGK 8 1000 210.0 185.0 35.0 LM95235DIMMX/NOPB VSSOP DGK 8 3500 367.0 367.0 35.0 LM95235EIMM/NOPB VSSOP DGK 8 1000 210.0 185.0 35.
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