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LM20
SNIS106Q –DECEMBER 1999–REVISED JANUARY 2015
LM20 2.4-V, 10-µA, SC70, DSBGA Temperature Sensor
1 Features 3 Description
The LM20 is a precision analog output CMOS
1• Rated for −55°C to 130°C Range integrated-circuit temperature sensor that operates
• Available in SC70 and DSBGA Package over −55°C to 130°C. The power supply operating
• Predictable Curvature Error range is 2.4 V to 5.5 V. The transfer function of LM20
is predominately linear, yet has a slight predictable
• Suitable for Remote Applications parabolic curvature. The accuracy of the LM20 when
• Accuracy at 30°C ±1.5 to ±4°C (Maximum) specified to a parabolic transfer function is ±1.5°C at
• Accuracy at 130°C and −55°C ±2.5 to ±5°C an ambient temperature of 30°C. The temperature
(Maximum) error increases linearly and reaches a maximum of
±2.5°C at the temperature range extremes. The
• Power Supply Voltage Range 2.4 V to 5.5 V temperature range is affected by the power supply
• Current Drain 10 μA (Maximum) voltage. At a power supply voltage of 2.7 V to 5.5 V,
• Nonlinearity ±0.4% (Typical) the temperature range extremes are 130°C and
• Output Impedance 160 Ω(Maximum) −55°C. Decreasing the power supply voltage to 2.4 V
changes the negative extreme to −30°C, while the
• Load Regulation positive extreme remains at 130°C.
0μA < IL< 16 μA−2.5 mV (Maximum) The LM20 quiescent current is less than 10 μA.
2 Applications Therefore, self-heating is less than 0.02°C in still air.
Shutdown capability for the LM20 is intrinsic because
• Cellular Phones its inherent low power consumption allows it to be
• Computers powered directly from the output of many logic gates
or does not necessitate shutdown.
• Power Supply Modules
• Battery Management Device Information(1)
• FAX Machines PART NUMBER PACKAGE BODY SIZE (NOM)
• Printers SC70 (5) 2.00 mm × 1.25 mm
LM20
• HVAC DSBGA (4) 0.96 mm × 0.96 mm
• Disk Drives (1) For all available packages, see the orderable addendum at
• Appliances the end of the data sheet.
Simplified Schematic Output Voltage vs Temperature
1
An IMPORTANT NOTICE at the end of this data sheet addresses availability, warranty, changes, use in safety-critical applications,
intellectual property matters and other important disclaimers. PRODUCTION DATA.
LM20
SNIS106Q –DECEMBER 1999–REVISED JANUARY 2015
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Table of Contents
7.3 Feature Description................................................... 8
1 Features.................................................................. 17.4 Device Functional Modes.......................................... 9
2 Applications ........................................................... 18 Application and Implementation ........................ 10
3 Description............................................................. 18.1 Application Information............................................ 10
4 Revision History..................................................... 28.2 Typical Applications ................................................ 11
5 Pin Configuration and Functions......................... 38.3 System Examples ................................................... 14
6 Specifications......................................................... 39 Power Supply Recommendations...................... 15
6.1 Absolute Maximum Ratings ...................................... 310 Layout................................................................... 15
6.2 ESD Ratings ............................................................ 410.1 Layout Guidelines ................................................. 15
6.3 Recommended Operating Conditions....................... 410.2 Layout Examples................................................... 15
6.4 Thermal Information.................................................. 410.3 Thermal Considerations........................................ 15
6.5 Electrical Characteristics: LM20B ............................ 411 Device and Documentation Support................. 17
6.6 Electrical Characteristics: LM20C ............................ 511.1 Trademarks........................................................... 17
6.7 Electrical Characteristics: LM20S ............................ 611.2 Electrostatic Discharge Caution............................ 17
6.8 Typical Characteristics ............................................. 711.3 Glossary................................................................ 17
7 Detailed Description.............................................. 812 Mechanical, Packaging, and Orderable
7.1 Overview................................................................... 8Information........................................................... 17
7.2 Functional Block Diagram......................................... 8
4 Revision History
Changes from Revision P (Feburary 2013) to Revision Q Page
• 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 section .............................. 1
Changes from Revision O (February 2013) to Revision P Page
• Changed layout of National Data Sheet to TI Format.......................................................................................................... 14
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5 Pin Configuration and Functions
DCK Package
5-Pin SC70
(Top View)
YZR Package
4-Pin DSBGA
(Top View)
Pin Functions
PIN TYPE DESCRIPTION
NAME DSBGA SC70
Device substrate and die attach paddle, connect to power supply negative
GND — 2 GND terminal. For optimum thermal conductivity to the PC board ground plane, pin
2 must be grounded. This pin may also be left floating.
GND A2 5 GND Device ground pin, connect to power supply negative terminal.
NC (pin 1) must be left floating or grounded. Other signal traces must not be
NC A1 1 — connected to this pin.
Analog
VOB1 3 Temperature sensor analog output
Output
V+B2 4 Power Positive power supply pin
6 Specifications
6.1 Absolute Maximum Ratings
over operating free-air temperature range (unless otherwise noted)(1)(2)
MIN MAX UNIT
Supply Voltage −0.2 6.5 V
Output Voltage −0.6 (V++ 0.6 ) V
Output Current 10 mA
Input Current at any pin(3) 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) Soldering process must comply with TI's Reflow Temperature Profile specifications. Refer to http://www.ti.com/packaging.
(3) 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.
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6.2 ESD Ratings VALUE UNIT
Human-body model (HBM), per ANSI/ESDA/JEDEC JS-001(1) ±2500
V(ESD) Electrostatic discharge 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.
6.3 Recommended Operating Conditions
over operating free-air temperature range (unless otherwise noted)(1)
MIN MAX UNIT
LM20B, LM20C with 2.4 V ≤V+≤2.7 V −30 130 °C
LM20B, LM20C with 2.7 V ≤V+≤5.5 V −55 130 °C
LM20S with 2.4 V ≤V+≤5.5 V −30 125 °C
LM20S with 2.7 V ≤V+≤5.5 V −40 125 °C
Supply Voltage Range (V+) 2.4 5.5 V
(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.
6.4 Thermal Information LM20
THERMAL METRIC(1) DCK (SC70) YZR (DSBGA) UNIT
5 PINS 4 PINS
RθJA Junction-to-ambient thermal resistance 282 197
RθJC(top) Junction-to-case (top) thermal resistance 93 2
RθJB Junction-to-board thermal resistance 62 40 °C/W
ψJT Junction-to-top characterization parameter 1.6 11
ψJB Junction-to-board characterization parameter 62 40
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.
6.5 Electrical Characteristics: LM20B
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(1) TYP(2) MAX(1) UNIT
TA= 25°C to 30°C –1.5 1.5 °C
TA= 130°C –2.5 2.5 °C
TA= 125°C –2.5 2.5 °C
TA= 100°C –2.2 2.2 °C
Temperature to Voltage Error TA= 85°C –2.1 2.1 °C
VO= (−3.88×10−6× T 2)+(−1.15×10−2×TA= 80°C –2.0 2.0 °C
T) + 1.8639 V(3)
TA= 0°C –1.9 1.9 °C
TA= –30°C –2.2 2.2 °C
TA= –40°C –2.3 2.3 °C
TA= –55°C –2.5 2.5 °C
Output Voltage at 0°C 1.8639 V
Variance from Curve ±1.0 °C
(1) Limits are ensured to TI's AOQL (Average Outgoing Quality Level).
(2) Typicals are at TJ= TA= 25°C and represent most likely parametric norm.
(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).
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Electrical Characteristics: LM20B (continued)
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(1) TYP(2) MAX(1) UNIT
Non-linearity(4) –20°C ≤TA≤80°C ±0.4%
Sensor Gain (Temperature Sensitivity or
Average Slope) to equation: –30°C ≤TA≤100°C –12.2 –11.77 –11.4 mV/°C
VO=−11.77 mV / °C×T+1.860 V
Output Impedance Sourcing IL0μA to 16 μA(5)(6) 160 Ω
Load Regulation(7) Sourcing IL0μA to 16 μA(3)(6) –2.5 mV
2.4 V ≤V+≤5.0 V 3.3 mV/V
Line Regulation(8) 5.0 V ≤V+≤5.5 V 11 mV
2.4 V ≤V+≤5.0 V; TA= 25°C 4.5 7 μA
Quiescent Current 5.0 V ≤V+≤5.5 V; TA= 25°C 4.5 9 μA
2.4 V ≤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 –11 nA/°C
Current
Shutdown Current V+≤0.8 V 0.02 μA
(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) The LM20 can at most sink 1 μA and source 16 μA.
(6) Load regulation or output impedance specifications apply over the supply voltage range of 2.4 V to 5.5 V.
(7) 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.
(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 Electrical Characteristics: LM20C
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(1) TYP(2) MAX(1) UNIT
TA= 25°C to 30°C –4 5 °C
TA= 130°C –5 5 °C
TA= 125°C –5 5 °C
TA= 100°C –4.7 4.7 °C
Temperature to Voltage Error TA= 85°C –4.6 4.6 °C
VO= (−3.88×10−6× T 2)+(−1.15×10−2×TA= 80°C –4.5 4.5 °C
T) + 1.8639 V(3)
TA= 0°C –4.4 4.4 °C
TA= –30°C –4.7 4.7 °C
TA= –40°C –4.8 4.8 °C
TA= –55°C –5.0 5.0 °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: –30°C ≤TA≤100°C –12.6 –11.77 –11.0 mV/°C
VO=−11.77 mV / °C×T+1.860 V
Output Impedance Sourcing IL0μA to 16 μA(5)(6) 160 Ω
(1) Limits are ensured to TI's AOQL (Average Outgoing Quality Level).
(2) Typicals are at TJ= TA= 25°C and represent most likely parametric norm.
(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) The LM20 can at most sink 1 μA and source 16 μA.
(6) Load regulation or output impedance specifications apply over the supply voltage range of 2.4 V to 5.5 V.
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Electrical Characteristics: LM20C (continued)
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(1) TYP(2) MAX(1) UNIT
Load Regulation(7) Sourcing IL0μA to 16 μA(5)(6) –2.5 mV
2.4 V ≤V+≤5.0 V 3.7 mV/V
Line Regulation(8) 5.0 V ≤V+≤5.5 V 11 mV
2.4 V ≤V+≤5.0 V; TA= 25°C 4.5 7 μA
Quiescent Current 5.0 V ≤V+≤5.5 V; TA= 25°C 4.5 9 μA
2.4 V ≤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 –11 nA/°C
Current
Shutdown Current V+≤0.8 V 0.02 μA
(7) 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.
(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.
6.7 Electrical Characteristics: LM20S
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(1) TYP(2) MAX(1) UNIT
TA= 25°C to 30°C –2.5 ±1.5 2.5 °C
TA= 125°C –3.5 3.5 °C
TA= 100°C –3.2 3.2 °C
Temperature to Voltage Error TA= 85°C –3.1 3.1 °C
VO= (−3.88×10−6×T 2)+(−1.15×10−2×TA= 80°C –3.0 3.0 °C
T) + 1.8639 V(3)
TA= 0°C –2.9 2.9 °C
TA= –30°C –3.3 3.3 °C
TA= –40°C –3.5 3.5 °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: –30°C ≤TA≤100°C –12.6 –11.77 –11.0 mV/°C
VO=−11.77 mV/ °C × T + 1.860 V
Output Impedance Sourcing IL0μA to 16 μA(5)(6) 160 Ω
Load Regulation(7) Sourcing IL0μA to 16 μA(5)(6) –2.5 mV
2.4 V ≤V+≤5.0 V 3.7 mV/V
Line Regulation(8) 5.0 V ≤V+≤5.5 V 11 mV
2.4 V ≤V+≤5.0 V; TA= 25°C 4.5 7 μA
Quiescent Current 5.0 V ≤V+≤5.5 V; TA= 25°C 4.5 9 μA
2.4 V ≤V+≤5.0 V 4.5 10 μA
(1) Limits are ensured to TI's AOQL (Average Outgoing Quality Level).
(2) Typicals are at TJ= TA= 25°C and represent most likely parametric norm.
(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) The LM20 can at most sink 1 μA and source 16 μA.
(6) Load regulation or output impedance specifications apply over the supply voltage range of 2.4 V to 5.5 V.
(7) 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.
(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.
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Electrical Characteristics: LM20S (continued)
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(1) TYP(2) MAX(1) UNIT
Change of Quiescent Current 2.4 V ≤V+≤5.5 V 0.7 μA
Temperature Coefficient of Quiescent –11 nA/°C
Current
Shutdown Current V+≤0.8 V 0.02 μA
6.8 Typical Characteristics
Figure 1. Temperature Error vs Temperature
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7 Detailed Description
7.1 Overview
The LM20 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 LM20 is predominately linear, yet has a slight predictable parabolic curvature. The accuracy of the LM20 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 for the LM20. 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 LM20 quiescent current is less than 10 μA. Therefore, self-heating is less than 0.02°C in still air. Shutdown
capability for the LM20 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
7.3 Feature Description
7.3.1 LM20 Transfer Function
The LM20 transfer function can be described in different ways with varying levels of precision. A simple linear
transfer function with good accuracy near 25°C is:
VO=−11.69 mV/°C × T + 1.8663 V (1)
Over the full operating temperature range of −55°C to 130°C, best accuracy can be obtained by using the
parabolic transfer function.
VO= (−3.88×10−6×T2)+(−1.15×10−2×T) + 1.8639 (2)
Using Equation 2, the following temperature to voltage output characteristic table can be generated.
Table 1. Temperature to Voltage Output Characteristic Table
TEMP VOUT TEMP VOUT TEMP VOUT TEMP VOUT TEMP VOUT TEMP VOUT TEMP VOUT
(°C) (V) (°C) (V) (°C) (V) (°C) (V) (°C) (V) (°C) (V) (°C) (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
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Feature Description (continued)
Table 1. Temperature to Voltage Output Characteristic Table (continued)
TEMP VOUT TEMP VOUT TEMP VOUT TEMP VOUT TEMP VOUT TEMP VOUT TEMP VOUT
(°C) (V) (°C) (V) (°C) (V) (°C) (V) (°C) (V) (°C) (V) (°C) (V)
-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:
(3)
7.4 Device Functional Modes
The only functional mode of the LM20 is that it has an analog output inversely proportional to temperature.
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8 Application and Implementation
NOTE
Information in the following applications sections is not part of the TI component
specification, and TI does not warrant its accuracy or completeness. TI’s customers are
responsible for determining suitability of components for their purposes. Customers should
validate and test their design implementation to confirm system functionality.
8.1 Application Information
The LM20 features make it suitable for many general temperature sensing applications. Multiple package options
expand on its, flexibility.
8.1.1 Capacitive Loads
The LM20 handles capacitive loading well. Without any precautions, the LM20 can drive any capacitive load less
than 300 pF as shown in Figure 2. Over the specified temperature range the LM20 has a maximum output
impedance of 160 Ω. In an extremely noisy environment, it may be necessary to add some filtering to minimize
noise pickup. It is recommended that 0.1 μF be added from V+to GND to bypass the power supply voltage, as
shown in Figure 4. In a noisy environment, it may even be necessary to add a capacitor from the output to
ground with a series resistor as shown in Figure 4. A 1-μF output capacitor with the 160-Ωmaximum output
impedance and a 200-Ωseries resistor will form a 442-Hz lowpass filter. Because the thermal time constant of
the LM20 is much slower, the overall response time of the LM20 will not be significantly affected.
In situations where a transient load current is placed on the circuit output the series resistance value may be
increased to compensate for any ringing that may be observed.
Figure 2. LM20 No Decoupling Required for Capacitive Loads Less Than 300 pF
Table 2. Capacitive Loading Isolation
Minimum R (Ω) C (µF)
200 1
470 0.1
680 0.01
1 k 0.001
Figure 3. LM20 With Compensation for Capacitive Loading Greater Than 300 pF
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Figure 4. LM20 With Filter for Noisy Environment and Capacitive Loading Greater Than 300 pF
NOTE
Either placement of resistor, as shown in Figure 3 and Figure 4, is just as effective.
8.1.2 LM20 DSBGA Light Sensitivity
Exposing the LM20 DSBGA package to bright sunlight may cause the output reading of the LM20 to drop by
1.5 V. In a normal office environment of fluorescent lighting the output voltage is minimally affected (less than a
millivolt drop). In either case, TI recommends that the LM20 DSBGA be placed inside an enclosure of some type
that minimizes its light exposure. Most chassis provide more than ample protection. The LM20 does not sustain
permanent damage from light exposure. Removing the light source will cause the output voltage of the LM20 to
recover to the proper value.
8.2 Typical Applications
8.2.1 Full-Range Celsius (Centigrade) Temperature Sensor (−55°C to 130°C) Operating from a Single Li-
Ion Battery Cell
The LM20 has a very low supply current and a wide supply range; therefore, it can easily be driven by a battery
as shown in Figure 5.
Figure 5. Full-Range Celsius (Centigrade) Temperature Sensor (−55°C To 130°C) Operating from a Single
Li-Ion Battery Cell
8.2.1.1 Design Requirements
Because the LM20 is a simple temperature sensor that provides an analog output, design requirements related
to layout are more important than electrical requirements. Refer to the Layout section for a detailed description.
8.2.1.2 Detailed Design Procedure
The LM20 transfer function can be described in different ways with varying levels of precision. A simple linear
transfer function with good accuracy near 25°C is:
VO=−11.69 mV/°C × T + 1.8663 V (4)
Over the full operating temperature range of −55°C to 130°C, best accuracy can be obtained by using the
parabolic transfer function.
VO= (−3.88×10−6×T2)+(−1.15×10−2×T) + 1.8639 (5)
Solving Equation 5 for T:
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LM20
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Typical Applications (continued)
(6)
An alternative to the quadratic equation a second order transfer function can be determined using the least-
squares method:
T = (−2.3654×VO2)+(−78.154×VO) + 153.857
where
• T is temperature express in °C and VOis the output voltage expressed in volts. (7)
A linear transfer function can be used over a limited temperature range by calculating a slope and offset that give
best results over that range. A linear transfer function can be calculated from the parabolic transfer function of
the LM20. The slope of the linear transfer function can be calculated using the Equation 8 equation:
m = −7.76 × 10−6× T −0.0115,
where
• T is the middle of the temperature range of interest and m is in V/°C. (8)
For example for the temperature range of TMIN =−30 to TMAX = 100°C:
T = 35°C (9)
and m = −11.77 mV/°C (10)
The offset of the linear transfer function can be calculated using the Equation 11 equation:
b = (VOP(TMAX)+VOP(T) −m × (TMAX+T))/2
where
• VOP(TMAX) is the calculated output voltage at TMAX using the parabolic transfer function for VO
• VOP(T) is the calculated output voltage at T using the parabolic transfer function for VO. (11)
The best fit linear transfer function for many popular temperature ranges was calculated in Table 3. As shown in
Table 3, the error introduced by the linear transfer function increases with wider temperature ranges.
Table 3. First Order Equations Optimized for Different Temperature Ranges
Temperature Range Maximum Deviation of Linear
Linear Equation Equation from Parabolic Equation (°C)
Tmin (°C) Tmax (°C)
−55 130 VO=−11.79 mV/°C × T + 1.8528 V ±1.41
−40 110 VO=−11.77 mV/°C × T + 1.8577 V ±0.93
−30 100 VO=−11.77 mV/°C × T + 1.8605 V ±0.70
-40 85 VO=−11.67 mV/°C × T + 1.8583 V ±0.65
−10 65 VO=−11.71 mV/°C × T + 1.8641 V ±0.23
35 45 VO=−11.81 mV/°C × T + 1.8701 V ±0.004
20 30 VO= –11.69 mV/°C × T + 1.8663 V ±0.004
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Product Folder Links: LM20
R1
4.1V
R3
R2
0.1 PF
U3LM4040
R4
VOUT
V+
VT
VTemp
+
-U1
LM20V+
U2
(High = overtemp alarm)
LM7211
LM20
www.ti.com
SNIS106Q –DECEMBER 1999–REVISED JANUARY 2015
Table 4. Output Voltage vs Temperature
Temperature (T) Typical VO
130°C 303 mV
100°C 675 mV
80°C 919 mV
30°C 1515 mV
25°C 1574 mV
0°C 1863.9 mV
–30°C 2205 mV
−40°C 2318 mV
−55°C 2485 mV
8.2.1.3 Application Curve
Figure 6. Output Voltage vs Temperature
8.2.2 Centigrade Thermostat
Figure 7. Centigrade Thermostat
8.2.2.1 Design Requirements
A simple thermostat can be created by using a reference (LM4040) and a comparator (LM7211) as shown in
Figure 7.
8.2.2.2 Detailed Design Procedure
The threshold values can be calculated using Equation 12 and Equation 13.
Copyright © 1999–2015, Texas Instruments Incorporated Submit Documentation Feedback 13
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VT1
VT2
VTEMP
VOUT
R1 + R2||R3
VT2 = (4.1)R2||R3
LM20
SNIS106Q –DECEMBER 1999–REVISED JANUARY 2015
www.ti.com
(12)
(13)
8.2.2.3 Application Curve
Figure 8. Thermostat Output Waveform
8.3 System Examples
8.3.1 Conserving Power Dissipation With Shutdown
The LM20 draws very little power; therefore, it can simply be shutdown by driving its supply pin with the output of
an logic gate as shown in Figure 9.
Figure 9. Conserving Power Dissipation With Shutdown
8.3.2 Analog-to-Digital Converter Input Stage
Most CMOS ADCs found in ASICs have a sampled data comparator input structure that is notorious for causing
grief to analog output devices such as the LM20 and many operational amplifiers. The cause of this grief is the
requirement of instantaneous charge of the input sampling capacitor in the ADC. This requirement is easily
accommodated by the addition of a capacitor. Because not all ADCsFigure 10 have identical input stages, the
charge requirements will vary necessitating a different value of compensating capacitor. This ADC is shown as
an example only. If a digital output temperature is required, refer to devices such as the LM74.
Figure 10. Suggested Connection to a Sampling Analog to Digital Converter Input Stage
14 Submit Documentation Feedback Copyright © 1999–2015, Texas Instruments Incorporated
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NC
GND
Vo
GND
NC
V+
NC
GND
Vo
GND
V+
LM20
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SNIS106Q –DECEMBER 1999–REVISED JANUARY 2015
9 Power Supply Recommendations
The LM20 has a very wide 2.4-V to 5.5-V power supply voltage range that makes ideal for many applications. In
noisy environments, TI recommends adding at minimum 0.1 μF from V+ to GND to bypass the power supply
voltage. Larger capacitances maybe required and are dependent on the power-supply noise.
10 Layout
10.1 Layout Guidelines
The LM20 can be easily applied in the same way as other integrated-circuit temperature sensors. It can be glued
or cemented to a surface. The temperature that the LM20 is sensing is within approximately 0.02°C of the
surface temperature to which the leads of the LM20 are attached.
Implementing the integrated-circuit temperature sensors presumes that the ambient air temperature is almost the
same as the surface temperature; if the air temperature were much higher or lower than the surface temperature,
the actual temperature measured would be at an intermediate temperature between the surface temperature and
the air temperature.
To ensure good thermal conductivity, the backside of the LM20 die is directly attached to the pin 2 GND. The
temperatures of the lands and traces to the other leads of the LM20 will also affect the temperature that is
sensed.
Alternatively, the LM20 can be mounted inside a sealed-end metal tube, and can then be dipped into a bath or
screwed into a threaded hole in a tank. As with any IC, the LM20 and accompanying wiring and circuits must be
kept insulated and dry, to avoid leakage and corrosion. This is especially true if the circuit may operate at cold
temperatures where condensation can occur. Printed-circuit coatings and varnishes such as a conformal coating
and epoxy paints or dips are often used to ensure that moisture cannot corrode the LM20 or its connections.
10.2 Layout Examples
Figure 11. Layout Used for No Heat Sink Measurements
Figure 12. Layout Used for Measurements With Small Heat Sink
10.3 Thermal Considerations
The thermal resistance junction to ambient (RθJA) is the parameter used to calculate the rise of a device junction
temperature due to its power dissipation. For the LM20, the equation used to calculate the rise in the die
temperature is as follows:
TJ= TA+ RθJA [(V+IQ) + (V+−VO) IL]
where
• IQis the quiescent current and ILis the load current on the output. Because the junction temperature of LM20 is
the actual temperature being measured, take care to minimize the load current that the LM20 is required to
drive. (14)
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Thermal Considerations (continued)
Table 5 summarizes the rise in die temperature of the LM20 without any loading and the thermal resistance for
different conditions.
Table 5. Temperature Rise of LM20 Due to Self-Heating and Thermal Resistance (RΘJA)
See more Layout Examples
SC70-5 SC70-5
No Heat Sink Small Heat Sink
RθJA TJ−TARθJA TJ−TA
(°C/W) (°C) (°C/W) (°C)
Still air 412 0.2 350 0.19
Moving air 312 0.17 266 0.15
DSBGA
No Heat Sink
RθJA TJ−TA
(°C/W) (°C)
Still air 340 0.18
16 Submit Documentation Feedback Copyright © 1999–2015, Texas Instruments Incorporated
Product Folder Links: LM20
LM20
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SNIS106Q –DECEMBER 1999–REVISED JANUARY 2015
11 Device and Documentation Support
11.1 Trademarks
All trademarks are the property of their respective owners.
11.2 Electrostatic Discharge Caution
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.
11.3 Glossary
SLYZ022 —TI Glossary.
This glossary lists and explains terms, acronyms, and definitions.
12 Mechanical, Packaging, and Orderable Information
The following pages include mechanical, packaging, and orderable information. This information is the most
current data available for the designated devices. This data is subject to change without notice and revision of
this document. For browser-based versions of this data sheet, refer to the left-hand navigation.
Copyright © 1999–2015, Texas Instruments Incorporated Submit Documentation Feedback 17
Product Folder Links: LM20
PACKAGE OPTION ADDENDUM
www.ti.com 11-Jan-2021
Addendum-Page 1
PACKAGING INFORMATION
Orderable Device Status
(1)
Package Type Package
Drawing Pins Package
Qty Eco Plan
(2)
Lead finish/
Ball material
(6)
MSL Peak Temp
(3)
Op Temp (°C) Device Marking
(4/5)
Samples
LM20BIM7 NRND SC70 DCK 5 1000 Non-RoHS
& Green Call TI Call TI -55 to 130 T2B
LM20BIM7/NOPB ACTIVE SC70 DCK 5 1000 RoHS & Green SN Level-1-260C-UNLIM -55 to 130 T2B
LM20BIM7X NRND SC70 DCK 5 3000 Non-RoHS
& Green Call TI Call TI -55 to 130 T2B
LM20BIM7X/NOPB ACTIVE SC70 DCK 5 3000 RoHS & Green Call TI | SN Level-1-260C-UNLIM -55 to 130 T2B
LM20CIM7/NOPB ACTIVE SC70 DCK 5 1000 RoHS & Green SN Level-1-260C-UNLIM -55 to 130 T2C
LM20CIM7X NRND SC70 DCK 5 3000 Non-RoHS
& Green Call TI Call TI -55 to 130 T2C
LM20CIM7X/NOPB ACTIVE SC70 DCK 5 3000 RoHS & Green SN Level-1-260C-UNLIM -55 to 130 T2C
LM20SITL/NOPB ACTIVE DSBGA YZR 4 250 RoHS & Green SNAGCU Level-1-260C-UNLIM -40 to 125
LM20SITLX/NOPB ACTIVE DSBGA YZR 4 3000 RoHS & Green SNAGCU Level-1-260C-UNLIM -40 to 125
(1) The marketing status values are defined as follows:
ACTIVE: Product device recommended for new designs.
LIFEBUY: TI has announced that the device will be discontinued, and a lifetime-buy period is in effect.
NRND: Not recommended for new designs. Device is in production to support existing customers, but TI does not recommend using this part in a new design.
PREVIEW: Device has been announced but is not in production. Samples may or may not be available.
OBSOLETE: TI has discontinued the production of the device.
(2) RoHS: TI defines "RoHS" to mean semiconductor products that are compliant with the current EU RoHS requirements for all 10 RoHS substances, including the requirement that RoHS substance
do not exceed 0.1% by weight in homogeneous materials. Where designed to be soldered at high temperatures, "RoHS" products are suitable for use in specified lead-free processes. TI may
reference these types of products as "Pb-Free".
RoHS Exempt: TI defines "RoHS Exempt" to mean products that contain lead but are compliant with EU RoHS pursuant to a specific EU RoHS exemption.
Green: TI defines "Green" to mean the content of Chlorine (Cl) and Bromine (Br) based flame retardants meet JS709B low halogen requirements of <=1000ppm threshold. Antimony trioxide based
flame retardants must also meet the <=1000ppm threshold requirement.
(3) MSL, Peak Temp. - The Moisture Sensitivity Level rating according to the JEDEC industry standard classifications, and peak solder temperature.
(4) There may be additional marking, which relates to the logo, the lot trace code information, or the environmental category on the device.
PACKAGE OPTION ADDENDUM
www.ti.com 11-Jan-2021
Addendum-Page 2
(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.
(6) Lead finish/Ball material - Orderable Devices may have multiple material finish options. Finish options are separated by a vertical ruled line. Lead finish/Ball material values may wrap to two
lines if the finish value exceeds the maximum column width.
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. TI has taken and
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.
In no event shall TI's liability arising out of such information exceed the total purchase price of the TI part(s) at issue in this document sold by TI to Customer on an annual basis.
TAPE AND REEL INFORMATION
*All dimensions are nominal
Device Package
Type Package
Drawing Pins SPQ Reel
Diameter
(mm)
Reel
Width
W1 (mm)
A0
(mm) B0
(mm) K0
(mm) P1
(mm) W
(mm) Pin1
Quadrant
LM20BIM7 SC70 DCK 5 1000 178.0 8.4 2.25 2.45 1.2 4.0 8.0 Q3
LM20BIM7/NOPB SC70 DCK 5 1000 178.0 8.4 2.25 2.45 1.2 4.0 8.0 Q3
LM20BIM7X SC70 DCK 5 3000 178.0 8.4 2.25 2.45 1.2 4.0 8.0 Q3
LM20BIM7X/NOPB SC70 DCK 5 3000 178.0 8.4 2.25 2.45 1.2 4.0 8.0 Q3
LM20CIM7/NOPB SC70 DCK 5 1000 178.0 8.4 2.25 2.45 1.2 4.0 8.0 Q3
LM20CIM7X SC70 DCK 5 3000 178.0 8.4 2.25 2.45 1.2 4.0 8.0 Q3
LM20CIM7X/NOPB SC70 DCK 5 3000 178.0 8.4 2.25 2.45 1.2 4.0 8.0 Q3
LM20SITL/NOPB DSBGA YZR 4 250 178.0 8.4 1.04 1.04 0.76 4.0 8.0 Q1
LM20SITLX/NOPB DSBGA YZR 4 3000 178.0 8.4 1.04 1.04 0.76 4.0 8.0 Q1
PACKAGE MATERIALS INFORMATION
www.ti.com 29-Sep-2019
Pack Materials-Page 1
*All dimensions are nominal
Device Package Type Package Drawing Pins SPQ Length (mm) Width (mm) Height (mm)
LM20BIM7 SC70 DCK 5 1000 210.0 185.0 35.0
LM20BIM7/NOPB SC70 DCK 5 1000 210.0 185.0 35.0
LM20BIM7X SC70 DCK 5 3000 210.0 185.0 35.0
LM20BIM7X/NOPB SC70 DCK 5 3000 210.0 185.0 35.0
LM20CIM7/NOPB SC70 DCK 5 1000 210.0 185.0 35.0
LM20CIM7X SC70 DCK 5 3000 210.0 185.0 35.0
LM20CIM7X/NOPB SC70 DCK 5 3000 210.0 185.0 35.0
LM20SITL/NOPB DSBGA YZR 4 250 210.0 185.0 35.0
LM20SITLX/NOPB DSBGA YZR 4 3000 210.0 185.0 35.0
PACKAGE MATERIALS INFORMATION
www.ti.com 29-Sep-2019
Pack Materials-Page 2
MECHANICAL DATA
YZR0004xxx
www.ti.com
TLA04XXX (Rev D)
0.600±0.075 D
E
4215042/A 12/12
A
. All linear dimensions are in millimeters. Dimensioning and tolerancing per ASME Y14.5M-1994.
B. This drawing is subject to change without notice.
NOTES:
D: Max =
E: Max =
0.994 mm, Min =
0.994 mm, Min =
0.933 mm
0.933 mm
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