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  • LMT89 2.4-V, 10-µA, SC70 Temperature Sensor

    • SNIS176A March   2013  – January 2015 LMT89

      PRODUCTION DATA.  

  • CONTENTS
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  • LMT89 2.4-V, 10-µA, SC70 Temperature Sensor
  1. 1 Features
  2. 2 Applications
  3. 3 Description
  4. 4 Revision History
  5. 5 Pin Configuration and Functions
  6. 6 Specifications
    1. 6.1 Absolute Maximum Ratings
    2. 6.2 ESD Ratings
    3. 6.3 Recommended Operating Conditions
    4. 6.4 Thermal Information
    5. 6.5 Electrical Characteristics
    6. 6.6 Typical Characteristics
  7. 7 Detailed Description
    1. 7.1 Overview
    2. 7.2 Functional Block Diagram
    3. 7.3 Feature Description
      1. 7.3.1 LMT89 Transfer Function
    4. 7.4 Device Functional Modes
  8. 8 Application and Implementation
    1. 8.1 Application Information
      1. 8.1.1 Capacitive Loads
    2. 8.2 Typical Applications
      1. 8.2.1 Full-Range Centigrade Temperature Sensor
        1. 8.2.1.1 Design Requirements
        2. 8.2.1.2 Detailed Design Procedure
        3. 8.2.1.3 Application Curve
      2. 8.2.2 Centigrade Thermostat
        1. 8.2.2.1 Design Requirements
        2. 8.2.2.2 Detailed Design Procedure
        3. 8.2.2.3 Application Curve
    3. 8.3 System Examples
      1. 8.3.1 Conserving Power Dissipation With Shutdown
      2. 8.3.2 Analog-to-Digital Converter Input Stage
  9. 9 Power Supply Recommendations
  10. 10Layout
    1. 10.1 Layout Guidelines
    2. 10.2 Layout Example
  11. 11Device and Documentation Support
    1. 11.1 Trademarks
    2. 11.2 Electrostatic Discharge Caution
    3. 11.3 Glossary
  12. 12Mechanical, Packaging, and Orderable Information
  13. IMPORTANT NOTICE

Package Options

Mechanical Data (Package|Pins)
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    • MPDS025K
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DATA SHEET

LMT89 2.4-V, 10-µA, SC70 Temperature Sensor

1 Features

  • Cost-Effective Alternative to Thermistors
  • Rated for full −55°C to 130°C Range
  • Available in an SC70 Package
  • Predictable Curvature Error
  • Suitable for Remote Applications

2 Applications

  • Industrial
  • HVAC
  • Automotive
  • Disk Drives
  • Portable Medical Instruments
  • Computers
  • Battery Management
  • Printers
  • Power Supply Modules
  • FAX Machines
  • Mobile Phones
  • Automotive

3 Description

The LMT89 device is a precision analog output CMOS integrated-circuit temperature sensor that operates over a −55°C to 130°C temperature range. The power supply operating range is 2.4 V to 5.5 V. The transfer function of LMT89 device is predominately linear, yet has a slight predictable parabolic curvature. The accuracy of the LMT89 device, when specified to a parabolic transfer function, is typically ±1.5°C at an ambient temperature of 30°C. The temperature error increases linearly and reaches a maximum of ±2.5°C at the temperature range extremes. The temperature range is affected by the power supply voltage. At a power supply voltage of 2.7 V to 5.5 V, the temperature range extremes are 130°C and −55°C. Decreasing the power supply voltage to 2.4 V changes the negative extreme to −30°C, while the positive remains at 130°C.

The quiescent current of the LMT89 device is less than 10 μA. Therefore, self-heating is less than 0.02°C in still air. Shutdown capability for the LMT89 device is intrinsic because its inherent low power consumption allows it to be powered directly from the output of many logic gates or does not necessitate shutdown at all.

The LMT89 device is a cost-competitive alternative to thermistors.

Device Information(1)

PART NUMBER PACKAGE BODY SIZE (NOM)
LMT89 SOT (5) 2.00 mm × 1.25 mm
  1. For all available packages, see the orderable addendum at the end of the datasheet.

Simplified Schematic

typ_app_nis176.gif

Output Voltage vs Temperature

output_voltage_vs_temperature_nis176.gif

4 Revision History

Changes from * Revision (March 2013) to A Revision

  • Added Pin Configuration and Functions section, ESD Ratings table, Feature Description section, Device Functional Modes, Application and Implementation section, Power Supply Recommendations section, Layout section, Device and Documentation Support section, and Mechanical, Packaging, and Orderable Information sectionGo

5 Pin Configuration and Functions

SC70-5 Top View
top_view_pack_number_nis176.gif

Pin Functions

PIN I/O DESCRIPTION
NO. NAME
1 NC — NC (pin 1) must be left floating or grounded. Other signal traces must not be connected to this pin.
2 GND GND Device substrate and die attach paddle, connect to power supply negative terminal. For optimum thermal conductivity to the PC board ground plane, pin 2 must be grounded. This pin may also be left floating.
3 VO Analog Output Temperature sensor analog output
4 V+ Power Positive power supply pin
5 GND GND Device ground pin, connect to power supply negative terminal.

6 Specifications

6.1 Absolute Maximum Ratings

over operating free-air temperature range (unless otherwise noted)(1)(3)
MIN MAX UNIT
Supply Voltage −0.2 6.5 V
Output Voltage (V+ + 0.6 V) −0.6 V
Output Current 10 mA
Input Current at any pin(2) 5 mA
Maximum Junction Temperature (TJMAX) 150 °C
Storage temperature (Tstg) −65 150 °C
(1) Stresses beyond those listed under Absolute Maximum Ratings may cause permanent damage to the device. These are stress ratings only, which do not imply functional operation of the device at these or any other conditions beyond those indicated under Recommended Operating Conditions. Exposure to absolute-maximum-rated conditions for extended periods may affect device reliability.
(2) When the input voltage (VI) at any pin exceeds power supplies (VI < GND or VI > V+), the current at that pin should be limited to 5 mA.
(3) Soldering process must comply with the Reflow Temperature Profile specifications. Refer to http://www.ti.com/packaging.. Reflow temperature profiles are different for lead-free and non-lead-free packages.

6.2 ESD Ratings

VALUE UNIT
V(ESD)(3) Electrostatic discharge Human-body model (HBM), per ANSI/ESDA/JEDEC JS-001(1) ±2500 V
Charged-device model (CDM), per JEDEC specification JESD22-C101(2) ±250
(1) JEDEC document JEP155 states that 500-V HBM allows safe manufacturing with a standard ESD control process.
(2) JEDEC document JEP157 states that 250-V CDM allows safe manufacturing with a standard ESD control process.
(3) Accuracy is defined as the error between the measured and calculated output voltage at the specified conditions of voltage, current, and temperature (expressed in°C).

6.3 Recommended Operating Conditions

over operating free-air temperature range (unless otherwise noted)
MIN MAX UNIT
LMT89 with 2.4 V ≤ V+ ≤ 2.7 V −30 130 °C
LMT89 with 2.7 V ≤ V+ ≤ 5.5 V −55 130 °C
Supply Voltage Range (V+) 2.4 5.5 V

6.4 Thermal Information

THERMAL METRIC(1) LMT89 UNIT
SOT
5 PINS
RθJA Junction-to-ambient thermal resistance 282 °C/W
RθJC(top) Junction-to-case (top) thermal resistance 93
RθJB Junction-to-board thermal resistance 62
ψJT Junction-to-top characterization parameter 1.6
ψJB Junction-to-board characterization parameter 62
RθJC(bot) Junction-to-case (bottom) thermal resistance —
(1) For more information about traditional and new thermal metrics, see the IC Package Thermal Metrics application report, SPRA953. For measured thermal resistance using specific printed circuit board layouts for the LMT89, see Layout.

6.5 Electrical Characteristics

Unless otherwise noted, these specifications apply for V+ = 2.7 VDC. All limits TA = TJ = TMIN to TMAX, unless otherwise noted.
PARAMETER TEST CONDITIONS MIN(2) TYP(1) MAX(2) UNIT
Temperature to Voltage Error
VO = (−3.88 × 10−6× T2) + (−1.15 × 10−2 × T) + 1.8639 V(3)		 –2.5 ±1.5 2.5 °C
Output Voltage at 0°C 1.8639 V
Variance from Curve ±1.0 °C
Non-Linearity (4) –20°C ≤ TA ≤ 80°C ±0.4%
Sensor Gain (Temperature Sensitivity or Average Slope) to equation:
VO = −11.77 mV/°C × T + 1.860 V		 –30°C ≤ TA ≤ 100°C –12.2 –11.77 –11.4 mV/°C
Output Impedance Sourcing IL 0 μA to 16 μA (6)(7) 160 Ω
Load Regulation(5) Sourcing IL 0 μA to 16 μA (6)(7) –2.5 mV
Line Regulation(8) 2.4 V ≤ V+ ≤ 5.0 V 3.3 mV/V
5.0 V ≤ V+ ≤ 5.5 V 11 mV
Quiescent Current 2.4V ≤ V+ ≤ 5.0 V; TA = 25°C 4.5 7 μA
5.0V ≤ V+ ≤ 5.5 V; TA = 25°C 4.5 9 μA
2.4V ≤ V+ ≤ 5.0 V 4.5 10 μA
Change of Quiescent Current 2.4 V ≤ V+ ≤ 5.5 V 0.7 μA
Temperature Coefficient of Quiescent Current –11 nA/°C
Shutdown Current V+ ≤ 0.8 V 0.02 μA
(1) Typical values are at TJ = TA = 25°C and represent most likely parametric norm.
(2) Limits are specified to TI's AOQL (Average Outgoing Quality Level).
(3) Accuracy is defined as the error between the measured and calculated output voltage at the specified conditions of voltage, current, and temperature (expressed in°C).
(4) Non-Linearity is defined as the deviation of the calculated output-voltage-versus-temperature curve from the best-fit straight line, over the temperature range specified.
(5) Regulation is measured at constant junction temperature, using pulse testing with a low duty cycle. Changes in output due to heating effects can be computed by multiplying the internal dissipation by the thermal resistance.
(6) The LMT89 can at most sink 1 μA and source 16 μA.
(7) Load regulation or output impedance specifications apply over the supply voltage range of 2.4 V to 5.5 V.
(8) Line regulation is calculated by subtracting the output voltage at the highest supply input voltage from the output voltage at the lowest supply input voltage.

6.6 Typical Characteristics

C001_SNIS176.png
Figure 1. Temperature Sensor Accuracy

7 Detailed Description

7.1 Overview

The LMT89 device is a precision analog output CMOS integrated-circuit temperature sensor that operates over a temperature range of −55°C to 130°C . The power supply operating range is 2.4 V to 5.5 V. The transfer function of LMT89 is predominately linear, yet has a slight predictable parabolic curvature. The accuracy of the LMT89 device, when specified to a parabolic transfer function, is typically ±1.5°C at an ambient temperature of 30°C. The temperature error increases linearly and reaches a maximum of ±5°C at the temperature range extremes. The temperature range is affected by the power supply voltage. At a power supply voltage of 2.7 V to 5.5 V, the temperature range extremes are 130°C and −55°C. Decreasing the power supply voltage to 2.4 V changes the negative extreme to −30°C, while the positive remains at 130°C.

The LMT89 quiescent current is less than 10 μA. Therefore, self-heating is less than 0.02°C in still air. Shutdown capability for the LMT89 is intrinsic because its inherent low power consumption allows it to be powered directly from the output of many logic gates or does not necessitate shutdown at all.

The temperature sensing element is comprised of a simple base emitter junction that is forward biased by a current source. The temperature sensing element is then buffered by an amplifier and provided to the OUT pin. The amplifier has a simple class A output stage thus providing a low impedance output that can source 16 µA and sink 1 µA.

7.2 Functional Block Diagram

FBD_01_SNIS176.gif

7.3 Feature Description

7.3.1 LMT89 Transfer Function

The transfer function of the LMT89 device can be described in different ways with varying levels of precision. A simple linear transfer function with good accuracy near 25°C is shown in Equation 1.

Equation 1. VO = −11.69 mV/°C × T + 1.8663 V

Over the full operating temperature range of −55°C to 130°C, best accuracy can be obtained by using the parabolic transfer function.

Equation 2. VO = (−3.88 × 10−6 × T2) + (−1.15 × 10−2 × T) + 1.8639

Using Equation 2 the following temperature to voltage output characteristic table can be generated.

Table 1. Temperature to Voltage Output Characteristic Table

TEMP
(°C)		 VOUT
(V)		 TEMP
(°C)		 VOUT
(V)		 TEMP
(°C)		 VOUT
(V)		 TEMP
(°C)		 VOUT
(V)		 TEMP
(°C)		 VOUT
(V)		 TEMP
(°C)		 VOUT
(V)		 TEMP
(°C)		 VOUT
(V)
–55 2.4847 –28 2.1829 –1 1.8754 26 1.5623 53 1.2435 80 0.9191 107 0.5890
–54 2.4736 –27 2.1716 0 1.8639 27 1.5506 54 1.2316 81 0.9069 108 0.5766
–53 2.4625 –26 2.1603 1 1.8524 28 1.5389 55 1.2197 82 0.8948 109 0.5643
–52 2.4514 –25 2.1490 2 1.8409 29 1.5271 56 1.2077 83 0.8827 110 0.5520
–51 2.4403 –24 2.1377 3 1.8294 30 1.5154 57 1.1958 84 0.8705 111 0.5396
–50 2.4292 –23 2.1263 4 1.8178 31 1.5037 58 1.1838 85 0.8584 112 0.5272
–49 2.4181 –22 2.1150 5 1.8063 32 1.4919 59 1.1719 86 0.8462 113 0.5149
–48 2.4070 –21 2.1037 6 1.7948 33 1.4802 60 1.1599 87 0.8340 114 0.5025
–47 2.3958 –20 2.0923 7 1.7832 34 1.4684 61 1.1480 88 0.8219 115 0.4901
–46 2.3847 –19 2.0810 8 1.7717 35 1.4566 62 1.1360 89 0.8097 116 0.4777
–45 2.3735 –18 2.0696 9 1.7601 36 1.4449 63 1.1240 90 0.7975 117 0.4653
–44 2.3624 –17 2.0583 10 1.7485 37 1.4331 64 1.1120 91 0.7853 118 0.4529
–43 2.3512 –16 2.0469 11 1.7369 38 1.4213 65 1.1000 92 0.7731 119 0.4405
–42 2.3401 –15 2.0355 12 1.7253 39 1.4095 66 1.0880 93 0.7608 120 0.4280
–41 2.3289 –14 2.0241 13 1.7137 40 1.3977 67 1.0760 94 0.7486 121 0.4156
–40 2.3177 –13 2.0127 14 1.7021 41 1.3859 68 1.0640 95 0.7364 122 0.4032
–39 2.3065 –12 2.0013 15 1.6905 42 1.3741 69 1.0519 96 0.7241 123 0.3907
–38 2.2953 –11 1.9899 16 1.6789 43 1.3622 70 1.0399 97 0.7119 124 0.3782
–37 2.2841 –10 1.9785 17 1.6673 44 1.3504 71 1.0278 98 0.6996 125 0.3658
–36 2.2729 –9 1.9671 18 1.6556 45 1.3385 72 1.0158 99 0.6874 126 0.3533
–35 2.2616 –8 1.9557 19 1.6440 46 1.3267 73 1.0037 100 0.6751 127 0.3408
–34 2.2504 –7 1.9442 20 1.6323 47 1.3148 74 0.9917 101 0.6628 128 0.3283
–33 2.2392 –6 1.9328 21 1.6207 48 1.3030 75 0.9796 102 0.6505 129 0.3158
–32 2.2279 –5 1.9213 22 1.6090 49 1.2911 76 0.9675 103 0.6382 130 0.3033
–31 2.2167 –4 1.9098 23 1.5973 50 1.2792 77 0.9554 104 0.6259 — —
–30 2.2054 –3 1.8984 24 1.5857 51 1.2673 78 0.9433 105 0.6136 — —
–29 2.1941 –2 1.8869 25 1.5740 52 1.2554 79 0.9312 106 0.6013 — —

Solving Equation 2 for T:

Equation 3. equation_3_nis176.gif

For other methods of calculating T, see Detailed Design Procedure.

7.4 Device Functional Modes

The only functional mode of the LMT89 device is that it has an analog output inversely proportional to temperature.

 
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