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LM90

www.ti.com

SNIS126A –MAY 2004–REVISED MARCH 2013

LM90 ±3°C Accurate, Remote Diode and Local Digital Temperature Sensor with Two-Wire

Interface

Check for Samples: LM90

FEATURES

DESCRIPTION

The LM90 is an 11-bit digital temperature sensor with

• Accurately Senses Die Temperature of Remote

a 2-wire System Management Bus (SMBus) serial

ICs or Diode Junctions

interface. The LM90 accurately measures its own

• Offset Register Allows Sensing a Variety of

temperature as well as the temperature of an external

Thermal Diodes Accurately

device, such as processor thermal diode or diode

connected transistor such as the 2N3904. The

• On-board Local Temperature Sensing

temperature of any ASIC can be accurately

• 10 Bit Plus Sign Remote Diode Temperature

determined using the LM90 as long as a dedicated

Data Format, 0.125°C Resolution

diode (semiconductor junction) is available on the

• Diode Fault Detection Circuitry

target die. The LM90 remote sensor accuracy of ±3°C

is factory trimmed for the 1.008 typical non-ideality

• T_CRIT_A Output Useful for System Shutdown

factor of the mobile Pentium III thermal diode. The

(Open Diode does not Activate T_CRIT_A)

LM90 has an Offset register to allow measuring other

• ALERT Output Supports SMBus 2.0 Protocol

diodes without requiring continuous software

• SMBus 2.0 Compatible Interface, Supports

management.

TIMEOUT

Activation of the ALERT output occurs when any

• 8-pin VSSOP Package

temperature goes outside a preprogrammed window

set by the HIGH and LOW temperature limit registers

APPLICATIONS

or exceeds the T_CRIT temperature limit. Activation

of the T_CRIT_A occurs when any temperature

• System Thermal Management

exceeds the T_CRIT programmed limit. The LM90 is

(e.g. Laptop, Desktop, Workstations, Server)

pin and register compatible with the LM86, Analog

• Electronic Test Equipment

Devices ADM1032 and Maxim MAX6657/8.

• Office Electronics

KEY SPECIFICATIONS

• Supply Voltage 3.0 to 3.6 V

• Supply Current 0.8 mA (Typ)

• Local Temp Accuracy (Includes Quantization

Error)

– T

=25°C to 125°C, ±4.0 °C (Max)

• Remote Diode Temp Accuracy (Includes

Quantization Error)

– T

=30°C to 50°C, T

=60°C to 100°C, ±3.0 °C

(Max)

– T

=0°C to 85°C, T

=25°C to 125°C, ±4.0 °C

(Max)

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.

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 (31 pages)

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LM90 www.ti.com SNIS126A – MAY 2004 – REVISED MARCH 2013 LM90 ±3°C Accurate, Remote Diode and Local Digital Temperature Sensor with Two-Wire Interface Check for Samples: LM90 FEATURES DESCRIPTION • The LM90 is an 11-bit digital temperature sensor with a 2-wire System Management Bus (SMBus) serial interface. The LM90 accurately measures its own temperature as well as the temperature of an external device, such as processor thermal diode or diode connected transistor such as the 2N3904.
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LM90 SNIS126A – MAY 2004 – REVISED MARCH 2013 www.ti.com LM90 Simplified Block Diagram Connection Diagram Figure 1. 8-Lead VSSOP - TOP VIEW See DGK Package PIN DESCRIPTIONS 2 Label Pin # VDD 1 Function Typical Connection Positive Supply Voltage Input DC Voltage from 3.0 V to 3.6 V Diode Current Source To Diode Anode. Connected to remote discrete diode conected transistor junction or to the diode connected transistor junction on a remote IC whose die temperature is being sensed.
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LM90 www.ti.
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LM90 SNIS126A – MAY 2004 – 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) −0.3 V to 6.0 V Supply Voltage −0.5 V to 6.0 V Voltage at SMBData, SMBCLK, ALERT, T_CRIT_A −0.3 V to (VDD + 0.
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LM90 www.ti.com SNIS126A – MAY 2004 – REVISED MARCH 2013 Temperature-to-Digital Converter Characteristics (continued) 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. Typical (1) Limits (2) Units (Limit) 31.25 34.4 ms (max) SMBus Inactive, 16Hz conversion rate 0.8 1.
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LM90 SNIS126A – 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 LM90 fully meet or exceed the published specifications of the SMBus version 2.0.
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LM90 www.ti.com Pin Name VDD SNIS126A – MAY 2004 – REVISED MARCH 2013 PIN # D1 D2 D3 D4 D5 D6 D7 R1 SNP 1 x x (1) x x x D+ 2 D− 3 T_CRIT_ A 4 x x x ALERT 6 x x x SMBData 7 x x x SMBCLK 8 (1) ESD CLAMP x x x x x x x x x Note: An “x” indicates that the diode exists. Figure 2.
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LM90 SNIS126A – MAY 2004 – REVISED MARCH 2013 www.ti.com FUNCTIONAL DESCRIPTION The LM90 temperature sensor incorporates a delta VBE based temperature sensor using a Local or Remote and a 10-bit plus sign ADC (Delta-Sigma Analog-to-Digital Converter). The LM90 is compatible with the serial SMBus version 2.0 two-wire interface. Digital comparators compare the measured Local Temperature (LT) to the Local High (LHS), Local Low (LLS) and Local T_CRIT (LCS) user-programmable temperature limit registers.
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LM90 www.ti.com SNIS126A – MAY 2004 – REVISED MARCH 2013 THE ALERT OUTPUT The LM90's ALERT pin is an active-low open-drain output that is triggered by a temperature conversion that is outside the limits defined by the temperature setpoint registers. Reset of the ALERT output is dependent upon the selected method of use.
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LM90 SNIS126A – MAY 2004 – REVISED MARCH 2013 www.ti.com Configuration register). 4. Master attends to conditions that caused the ALERT to be triggered. The fan is started, setpoint limits are adjusted, etc. 5. Master resets the ALERT mask (D7 in the Configuration register). Figure 5.
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LM90 www.ti.com SNIS126A – MAY 2004 – REVISED MARCH 2013 fan started, setpoint limits adjusted, etc. 8. Master resets the ALERT mask (D7 in the Configuration register). The ARA, 000 1100, is a general call address. No device should ever be assigned this address. Bit D0 (the ALERT configure bit) in the FILTER and ALERT CONFIGURE REGISTER (xBF) must be set low in order for the LM90 to respond to the ARA command.
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LM90 SNIS126A – MAY 2004 – REVISED MARCH 2013 www.ti.com 3. Remote Diode Temperature set to 0°C until the end of the first conversion. 4. Status Register set to 00h. 5. Configuration register set to 00h; ALERT enabled, Remote T_CRIT alarm enabled and Local T_CRIT alarm enabled 6. 85°C Local and Remote T_CRIT temperature setpoints 7. 70°C Local and Remote HIGH temperature setpoints 8. 0°C Local and Remote LOW temperature setpoints 9.
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LM90 www.ti.com SNIS126A – MAY 2004 – REVISED MARCH 2013 OPEN-DRAIN OUTPUTS The SMBData, ALERT and T_CRIT_A outputs are open-drain outputs and do not have internal pull-ups. A “high” level will not be observed on these pins until pull-up current is provided by some external source, typically a pullup resistor. Choice of resistor value depends on many system factors but, in general, the pull-up resistor should be as large as possible.
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LM90 SNIS126A – MAY 2004 – REVISED MARCH 2013 www.ti.com SMBus Timing Diagrams Figure 8. (a) Serial Bus Write to the internal Command Register followed by a the Data Byte Figure 9. (b) Serial Bus Write to the Internal Command Register Figure 10.
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LM90 www.ti.com SNIS126A – MAY 2004 – REVISED MARCH 2013 DIGITAL FILTER In order to suppress erroneous remote temperature readings due to noise, the LM90 incorporates a userconfigured digital filter. The filter is accessed in the FILTER and ALERT CONFIGURE REGISTER at BFh. The filter can be set according to the following table. D2 D1 Filter 0 0 No Filter 0 1 Level 1 1 0 Level 1 1 1 Level 2 Level 2 sets maximum filtering.
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LM90 SNIS126A – MAY 2004 – REVISED MARCH 2013 www.ti.com Fault Queue In order to suppress erroneous ALERT or T_CRIT triggering the LM90 incorporates a Fault Queue. The Fault Queue acts to insure a remote temperature measurement is genuinely beyond a HIGH, LOW or T_CRIT setpoint by not triggering until three consecutive out of limit measurements have been made, see Figure 14. The fault queue defaults off upon power-up and may be activated by setting bit D0 in the Configuration register (09h) to “1”.
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LM90 www.ti.
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LM90 SNIS126A – MAY 2004 – REVISED MARCH 2013 www.ti.com D7: Busy: When set to “1” ADC is busy converting. CONFIGURATION REGISTER Table 4. CONFIGURATION REGISTER (Read Address 03h /Write Address 09h): D7 D6 D5 D4 D3 D2 D1 D0 ALERT mask RUN/STOP 0 Remote T_CRIT_A mask 0 Local T_CRIT_A mask 0 Fault Queue Power up default is with all bits “0” (zero) D7: ALERT mask: When set to “1” ALERT interrupts are masked. D6: RUN/STOP: When set to “1” SHUTDOWN is enabled.
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LM90 www.ti.com SNIS126A – MAY 2004 – REVISED MARCH 2013 For LHS and RHSHB: HIGH setpoint temperature data. Power up default is LHIGH = RHIGH = 70°C. 1LSB = 1°C. Two's complement format. Table 7. LOCAL and REMOTE HIGH SETPOINT REGISTERS (RHSLB) (Read/Write Address 13h): BIT D7 D6 D5 D4 D3 D2 D1 D0 Value 0.5 0.25 0.125 0 0 0 0 0 For RHSLB: Remote HIGH Setpoint Low Byte temperature data. Power up default is 0°C. 1LSB = 0.125°C. Two's complement format.
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LM90 SNIS126A – MAY 2004 – REVISED MARCH 2013 www.ti.com D7–D0: T_CRIT setpoint temperature data. Power up default is T_CRIT = 85°C. 1 LSB = 1°C, two's complement format. T_CRIT HYSTERESIS REGISTER (TH) Table 13. T_CRIT HYSTERESIS REGISTER (TH) (Read and Write Address 21h): BIT D7 D6 D5 D4 D3 D2 D1 D0 16 8 4 2 1 Value D7–D0: T_CRIT Hysteresis temperature. Power up default is TH = 10°C. 1 LSB = 1°C, maximum value = 31. FILTER and ALERT CONFIGURE REGISTER Table 14.
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LM90 www.ti.com SNIS126A – MAY 2004 – REVISED MARCH 2013 Figure 15. Mobile Pentium III or 3904 Temperature vs LM90 Temperature Reading Most silicon diodes do not lend themselves well to this application. It is recommended that a 2N3904 transistor base emitter junction be used with the collector tied to the base. A diode connected 2N3904 approximates the junction available on a Pentium III microprocessor for temperature measurement. Therefore, the LM90 can sense the temperature of this diode effectively.
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LM90 SNIS126A – MAY 2004 – REVISED MARCH 2013 www.ti.com 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 Pentium III Intel specifies a ±1% variation in η from part to part.
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LM90 www.ti.com SNIS126A – MAY 2004 – REVISED MARCH 2013 Figure 18. Compensating for an Untargeted Non-Ideality Factor Temperature errors associated with non-ideality may be reduced in a specific temperature range of concern through use of the offset registers (11h and 12h). Figure 18 shows how the offset register may be used to compensate for the non-ideality errors shown in Figure 17. For the case of non-ideality=1.008, the offset register was set to −0.
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LM90 SNIS126A – MAY 2004 – REVISED MARCH 2013 www.ti.com kept at least 2cm 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 LM90's GND pin is as close as possible to the Processors GND associated with the sense diode. 9. Leakage current between D+ and GND should be kept to a minimum.
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LM90 www.ti.com SNIS126A – MAY 2004 – REVISED MARCH 2013 REVISION HISTORY Changes from Original (March 2013) to Revision A • 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 continues to take reasonable steps to provide representative and accurate information but may not have conducted destructive testing or chemical analysis on incoming materials and chemicals. TI and TI suppliers consider certain information to be proprietary, and thus CAS numbers and other limited information may not be available for release.
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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 LM90CIMM VSSOP DGK 8 1000 178.0 12.4 5.3 3.4 1.4 8.0 12.0 Q1 LM90CIMM/NOPB VSSOP DGK 8 1000 178.0 12.4 5.3 3.4 1.4 8.0 12.0 Q1 LM90CIMMX/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) LM90CIMM VSSOP DGK 8 1000 210.0 185.0 35.0 LM90CIMM/NOPB VSSOP DGK 8 1000 210.0 185.0 35.0 LM90CIMMX/NOPB VSSOP DGK 8 3500 367.0 367.0 35.
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