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LM95221

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SNIS134B –MAY 2004–REVISED MARCH 2013

LM95221 Dual Remote Diode Digital Temperature Sensor with SMBus Interface

Check for Samples: LM95221

FEATURES

APPLICATIONS

• Accurately Senses Die Temperature of Remote

• Processor/Computer System Thermal

ICs or Diode Junctions Management (e.g. Laptop, Desktop,

Workstations, Server)

• Remote Diode Fault Detection

• Electronic Test Equipment

• On-board Local Temperature Sensing

• Office Electronics

• Remote Temperature Readings

– 0.125°C LSb

DESCRIPTION

– 10-bits Plus Sign or 11-bits Programmable

The LM95221 is a dual remote diode temperature

Resolution

sensor in an 8-lead VSSOP package. The 2-wire

– 11-bits Resolves Temperatures Above

serial interface of the LM95221 is compatible with

127°C

SMBus 2.0. The LM95221 can sense three

temperature zones, it can measure the temperature

• Local Temperature Readings

of its own die as well as two diode connected

– 0.25°C

transistors. The diode connected transistors can be a

– 9-bits Plus Sign

thermal diode as found in Pentium and AMD

processors or can simply be a diode connected

• Status Register Support

MMBT3904 transistor. The LM95221 resolution

• Programmable Conversion Rate Allows User

format for remote temperature readings can be

Optimization of Power Consumption

programmed to be 10-bits plus sign or 11-bits

• Shutdown Mode One-shot Conversion Control

unsigned. In the unsigned mode the LM95221 remote

diode readings can resolve temperatures above

• SMBus 2.0 Compatible Interface, Supports

127°C. Local temperature readings have a resolution

TIMEOUT

of 9-bits plus sign.

• 8-pin VSSOP Package

The temperature of any ASIC can be accurately

determined using the LM95221 as long as a

KEY SPECIFICATIONS

dedicated diode (semiconductor junction) is available

• Local Temperature Accuracy

on the target die. The LM95221 remote sensor

– T

= 0°C to 85°C ± 3.0°C (max) accuracy of ±1°C is factory trimmed for a series

resistance of 2.7 ohms and 1.008 non-ideality factor.

• Remote Diode Temperature Accuracy

– T

= 30°C to 50°C, TD = 45°C to 85°C

±1.0 °C (Max)

– T

= 0°C to 85°C, TD = 25°C to 140°C

±3.0°C (Max)

• Supply Voltage 3.0 V to 3.6 V

• Supply Current 2 mA (Typ)

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 (24 pages)

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LM95221 www.ti.com SNIS134B – MAY 2004 – REVISED MARCH 2013 LM95221 Dual Remote Diode Digital Temperature Sensor with SMBus Interface Check for Samples: LM95221 FEATURES APPLICATIONS • • 1 2 • • • • • • • • • Accurately Senses Die Temperature of Remote ICs or Diode Junctions Remote Diode Fault Detection On-board Local Temperature Sensing Remote Temperature Readings – 0.
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LM95221 SNIS134B – MAY 2004 – REVISED MARCH 2013 www.ti.com Simplified Block Diagram 3.0V-3.
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LM95221 www.ti.com SNIS134B – MAY 2004 – REVISED MARCH 2013 Typical Application +3.3V Standby C3* 2.2 nF Pentium® 4 PROCESSOR 1 2 3 C4* 2.2 nF 4 D1+ SMBCLK D1- SMBDAT R1 1.3k 8 R2 1.3k SMBCLK 7 SMBDAT 6 D2+ VDD 5 GND D2- LM95221 C1* 100 pF C2 0.1 PF SMBus Master Q1 MMBT3904 * Note, place close to LM95221 pins. These devices have limited built-in ESD protection.
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LM95221 SNIS134B – MAY 2004 – REVISED MARCH 2013 www.ti.com Temperature-to-Digital Converter Characteristic 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 LM95221. TD is the junction temperature of the remote thermal diode.
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LM95221 www.ti.com SNIS134B – MAY 2004 – REVISED MARCH 2013 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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LM95221 SNIS134B – MAY 2004 – REVISED MARCH 2013 www.ti.com 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 LM95221 fully meet or exceed the published specifications of the SMBus version 2.0.
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LM95221 www.ti.com SNIS134B – MAY 2004 – REVISED MARCH 2013 Typical Performance Characteristics Thermal Diode Capacitor or PCB Leakage Current Effect Remote Diode Temperature Reading Remote Temperature Reading Sensitivity to Thermal Diode Filter Capacitance Figure 4. Figure 5. Conversion Rate Effect on Average Power Supply Current Figure 6.
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LM95221 SNIS134B – MAY 2004 – REVISED MARCH 2013 www.ti.com FUNCTIONAL DESCRIPTION The LM95221 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 diode connected MMBT3904 transistors using a ΔVbe temperature sensing method. The 2-wire serial interface, of the LM95221, is compatible with SMBus 2.0 and I2C. Please see the SMBus 2.
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LM95221 www.ti.com SNIS134B – MAY 2004 – REVISED MARCH 2013 Figure 7. Conversion Rate Effect on Power Supply Current POWER-ON-DEFAULT STATES LM95221 always powers up to these known default states. The LM95221 remains in these states until after the first conversion. 1. Command Register set to 00h 2. Local Temperature set to 0°C 3. Remote Diode Temperature set to 0°C until the end of the first conversion 4. Status Register depends on state of thermal diode inputs 5.
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LM95221 SNIS134B – MAY 2004 – REVISED MARCH 2013 www.ti.com Table 1. 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 −0.125°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 2.
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LM95221 www.ti.com SNIS134B – MAY 2004 – REVISED MARCH 2013 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.
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LM95221 SNIS134B – MAY 2004 – REVISED MARCH 2013 www.ti.com SMBus Timing Diagrams 1 9 1 9 SMBCLK SMBDAT A6 A5 A4 A3 A2 D7 Ack by LM95221 A1 D6 A0 R/W Start by Master D5 D4 Frame 1 Serial Bus Address Byte D3 D2 SMBDAT (Continued) D0 Ack by LM95221 Frame 2 Command Byte 1 SMBCLK (Continued) D1 9 D7 D6 D5 D4 D3 D2 D1 D0 Ack by Stop LM95221 by Master Frame 3 Data Byte Figure 8.
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LM95221 www.ti.com SNIS134B – MAY 2004 – REVISED MARCH 2013 SERIAL INTERFACE RESET In the event that the SMBus Master is RESET while the LM95221 is transmitting on the SMBDAT line, the LM95221 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 LM95221 SMBus state machine resets to the SMBus idle state if either SMBDAT or SMBCLK are held low for more than 35ms (tTIMEOUT). Note that according to SMBus specification 2.
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LM95221 SNIS134B – MAY 2004 – REVISED MARCH 2013 www.ti.com STATUS REGISTER (Read Only Address 02h) D7 D6 D5 0 0 Busy D4 D3 D2 0 0 Reserved 0 D1 D0 RD2M RD1M Bits Name Description 7 Busy When set to "1" the part is converting. 6-2 Reserved Reports "0" when read. 1 Remote diode 2 missing (RD2M) Remote Diode 2 is missing. (i.e. D2+ shorted to VDD, Ground or D2-, or D2+ is floating). Temperature Reading is FFE0h which converts to 255.
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LM95221 www.ti.com SNIS134B – MAY 2004 – REVISED MARCH 2013 Table 6. Remote Temperature MSB (Read Only Address 11h, 12h) 10 bit plus sign format (1): (1) BIT D7 D6 D5 D4 D3 D2 D1 D0 Value SIGN 64 32 16 8 4 2 1 Temperature Data: LSb = 1°C. Table 7. Remote Temperature MSB (Read Only Address 11h, 12h) 11-bit unsigned format (1): BIT D7 D6 D5 D4 D3 D2 D1 D0 Value 128 64 32 16 8 4 2 1 (1) Table 8.
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LM95221 SNIS134B – MAY 2004 – REVISED MARCH 2013 www.ti.com 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: Vbe IF = IS e KVt - 1 where • • • • • • • • Vt = kqT q = 1.6×10−19 Coulombs (the electron charge), T = Absolute Temperature in Kelvin k = 1.
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LM95221 www.ti.com SNIS134B – MAY 2004 – REVISED MARCH 2013 The additional inaccuracy in the temperature measurement caused by η, can be eliminated if each temperature sensor is calibrated with the remote diode that it will be paired with. η, non-ideality Processor Family Series R min typ max Pentium II 1 1.0065 1.0173 Pentium III CPUID 67h 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.
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LM95221 SNIS134B – MAY 2004 – REVISED MARCH 2013 www.ti.com PCB LAYOUT FOR MINIMIZING NOISE Figure 12. 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 LM95221 can cause temperature conversion errors. Keep in mind that the signal level the LM95221 is trying to measure is in microvolts. The following guidelines should be followed: 1.
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LM95221 www.ti.com SNIS134B – MAY 2004 – REVISED MARCH 2013 REVISION HISTORY Changes from Revision A (March 2013) to Revision B • Page Changed layout of National Data Sheet to TI format ..........................................................................................................
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PACKAGE OPTION ADDENDUM www.ti.
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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 LM95221CIMM/NOPB VSSOP DGK 8 1000 178.0 12.4 5.3 3.4 1.4 8.0 12.0 Q1 LM95221CIMMX/NOPB VSSOP DGK 8 3500 330.0 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) LM95221CIMM/NOPB VSSOP DGK 8 1000 210.0 185.0 35.0 LM95221CIMMX/NOPB VSSOP DGK 8 3500 367.0 367.0 35.
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