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LMT89
SNIS176A – MARCH 2013 – REVISED JANUARY 2015
LMT89 2.4-V, 10-µA, SC70 Temperature Sensor
1 Features
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.
1
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
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
LMT89
PACKAGE
SOT (5)
BODY SIZE (NOM)
2.00 mm × 1.25 mm
(1) For all available packages, see the orderable addendum at
the end of the datasheet.
Simplified Schematic
Output Voltage vs Temperature
+2.4V to +5.5V
To MCU ADC
V+
VO
LMT89
GND
NC
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.
LMT89
SNIS176A – MARCH 2013 – REVISED JANUARY 2015
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Table of Contents
1
2
3
4
5
6
7
Features ..................................................................
Applications ...........................................................
Description .............................................................
Revision History.....................................................
Pin Configuration and Functions .........................
Specifications.........................................................
1
1
1
2
3
4
6.1
6.2
6.3
6.4
6.5
6.6
4
4
4
4
5
5
Absolute Maximum Ratings ......................................
ESD Ratings..............................................................
Recommended Operating Conditions.......................
Thermal Information ..................................................
Electrical Characteristics...........................................
Typical Characteristics .............................................
Detailed Description .............................................. 6
7.1 Overview ................................................................... 6
7.2 Functional Block Diagram ......................................... 6
7.3 Feature Description................................................... 6
7.4 Device Functional Modes.......................................... 7
8
Application and Implementation .......................... 8
8.1 Application Information.............................................. 8
8.2 Typical Applications .................................................. 9
8.3 System Examples ................................................... 11
9 Power Supply Recommendations...................... 12
10 Layout................................................................... 12
10.1 Layout Guidelines ................................................. 12
10.2 Layout Example .................................................... 13
11 Device and Documentation Support ................. 14
11.1 Trademarks ........................................................... 14
11.2 Electrostatic Discharge Caution ............................ 14
11.3 Glossary ................................................................ 14
12 Mechanical, Packaging, and Orderable
Information ........................................................... 14
4 Revision History
Changes from Original (March 2013) to Revision A
•
2
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
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5 Pin Configuration and Functions
SC70-5 Top View
V+
4
3
VO
LMT89
5
2
GND
1
GND
NC
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.
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6 Specifications
6.1 Absolute Maximum Ratings
over operating free-air temperature range (unless otherwise noted) (1) (2)
MIN
MAX
UNIT
−0.2
6.5
V
(V + 0.6 V)
−0.6
V
10
mA
Supply Voltage
+
Output Voltage
Output Current
Input Current at any pin (3)
5
mA
Maximum Junction Temperature (TJMAX)
−65
Storage temperature (Tstg)
(1)
(2)
(3)
150
°C
150
°C
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.
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.
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.
6.2 ESD Ratings
VALUE
Human-body model (HBM), per ANSI/ESDA/JEDEC JS-001
V(ESD) (1)
(1)
(2)
(3)
Electrostatic discharge
(2)
UNIT
±2500
Charged-device model (CDM), per JEDEC specification JESD22C101 (3)
V
±250
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).
JEDEC document JEP155 states that 500-V HBM allows safe manufacturing with a standard ESD control process.
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)
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
2.4
5.5
V
+
Supply Voltage Range (V )
6.4 Thermal Information
LMT89
THERMAL METRIC (1)
SOT
UNIT
5 PINS
RθJA
Junction-to-ambient thermal resistance
282
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)
4
°C/W
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.
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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 (1)
TYP (2)
MAX (1)
–2.5
±1.5
2.5
Temperature to Voltage Error
VO = (−3.88 × 10−6× T2) + (−1.15 × 10−2 × T)
+ 1.8639 V (3)
Output Voltage at 0°C
Variance from Curve
Non-Linearity
(4)
–20°C ≤ TA ≤ 80°C
UNIT
°C
1.8639
V
±1.0
°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
Output Impedance
Sourcing IL 0 μA to 16 μA
(5) (6)
160
Sourcing IL 0 μA to 16 μA
(5) (6)
–2.5
mV
3.3
mV/V
11
mV
7
μA
Load Regulation
(7)
–12.2
2.4 V ≤ V+ ≤ 5.0 V
Line Regulation (8)
5.0 V ≤ V+ ≤ 5.5 V
2.4V ≤ V+ ≤ 5.0 V; TA = 25°C
Quiescent Current
Change of Quiescent Current
4.5
(4)
(5)
(6)
(7)
(8)
mV/°C
Ω
5.0V ≤ V ≤ 5.5 V; TA = 25°C
4.5
9
μA
2.4V ≤ V+ ≤ 5.0 V
4.5
10
μA
2.4 V ≤ V+ ≤ 5.5 V
0.7
μA
–11
nA/°C
0.02
μA
V+ ≤ 0.8 V
Shutdown Current
–11.4
+
Temperature Coefficient of Quiescent Current
(1)
(2)
(3)
–11.77
Limits are specified to TI's AOQL (Average Outgoing Quality Level).
Typical values are at TJ = TA = 25°C and represent most likely parametric norm.
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).
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.
The LMT89 can at most sink 1 μA and source 16 μA.
Load regulation or output impedance specifications apply over the supply voltage range of 2.4 V to 5.5 V.
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.
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
5
MIN
MAX
Median
4
3
Accuracy (C)
2
1
0
±1
±2
±3
±4
±5
±60
±40
±20
0
20
40
60
80
DUT Temperature (C)
100 120 140
C001
Figure 1. Temperature Sensor Accuracy
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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
V+
VO
Thermal Diodes
GND
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.
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.
6
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Feature Description (continued)
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:
T
1481.96 2.1962 u 10 6
(1.8639 VO )
3.88 u 10
6
(3)
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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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 LMT89 has a very low supply current and a wide supply range therefore it can easily be driven by a battery
as shown in Figure 4.
8.1.1 Capacitive Loads
The LMT89 device handles capacitive loading well. Without any precautions, the LMT89 device can drive any
capacitive load less than 300 pF as shown in Figure 2. The specified temperature range the LMT89 device 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. TI recommends that 0.1 μF be added from V+ to GND to bypass the power
supply voltage, as shown in Figure 2. 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 2. A 1-μF output capacitor with the 160-Ω
maximum output impedance and a 200-Ω series resistor will form a 442-Hz lowpass filter. Because the thermal
time constant of the LMT89 device is much slower, the overall response time of the LMT89 device 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.
+
Heavy Capacitive Load, Wiring, Etc.
LMT89
To A High-Impedance Load
OUT
d
Figure 2. LMT89 No Decoupling Required for Capacitive Loads Less Than 300 pF
Table 2. Design Parameters
Minimum R (Ω)
C (µF)
200
1
470
0.1
680
0.01
1k
0.001
+
LMT89
0.1 µF Bypass
Optional
Heavy Capacitive Load, Wiring, Etc.
OUT
d
R
C
+
Heavy Capacitive Load, Wiring, Etc.
R
LMT89
0.1 µF Bypass
Optional
OUT
d
C
Figure 3. LMT89 With Filter for Noisy Environment and Capacitive Loading Greater Than 300 pF
8
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NOTE
Either placement of resistor, as shown in Figure 2 and Figure 3, is just as effective.
8.2 Typical Applications
8.2.1 Full-Range Centigrade Temperature Sensor
+2.4V to +5.5V
To MCU ADC
V+
VO
LMT89
GND
NC
Figure 4. 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
Design requirements related to layout are also important because the LMT89 device is a simple temperature
sensor that provides an analog output, refer to Layout for a detailed description.
8.2.1.2 Detailed Design Procedure
The LMT89 device output is shown in Equation 4.
VO = (−3.88 × 10−6 × T2) + (−1.15 × 10−2 × T) + 1.8639
(4)
Solve for T as shown in Equation 5:
T
1481.96 2.1962 u 106
(1.8639 VO )
3.88 u 10
6
where
•
T is temperature, and VO is the measured output voltage of the LMT89 device. Equation 5 is the most accurate
equation that can be used to calculate the temperature of the LMT89 device.
(5)
An alternative to the quadratic equation a second order transfer function can be determined using the least
squares method shown in Equation 6.
T = (−2.3654 × VO 2) + (−78.154 × VO ) + 153.857
where
•
T is temperature express in °C and VO is the output voltage expressed in volts.
(6)
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 LMT89 device. The slope of the linear transfer function can be calculated using Equation 7.
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. For example for the temperature range of
TMIN = −30 to TMAX = 100°C
(7)
T = 35°C
(8)
and
m = −11.77 mV/°C
(9)
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Typical Applications (continued)
The offset of the linear transfer function can be calculated using Equation 10.
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.
(10)
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
LINEAR EQUATION
MAXIMUM DEVIATION OF LINEAR EQUATION
FROM PARABOLIC EQUATION (°C)
130
VO = −11.79 mV/°C × T + 1.8528 V
±1.41
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
Tmin (°C)
Tmax (°C)
−55
−40
8.2.1.3 Application Curve
Figure 5. Output Voltage vs Temperature
10
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8.2.2 Centigrade Thermostat
V+
R3
R4
LM4040
U3
V+
VT
R1
4.1V
0.1 PF
LMT89
(High = overtemp alarm)
+
U1
-
R2
VOUT
LM7211
VTemp
U2
Figure 6. 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 6.
8.2.2.2 Detailed Design Procedure
The threshold values can be calculated using Equation 11 and Equation 12.
VT1 =
(4.1)R2
R2 + R1||R3
(11)
VT2 =
(4.1)R2||R3
R1 + R2||R3
(12)
8.2.2.3 Application Curve
VTEMP
VT1
VT2
VOUT
Figure 7. Thermostat Output Waveform
8.3 System Examples
8.3.1 Conserving Power Dissipation With Shutdown
The LMT89 device 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 8.
+VS
SHUTDOWN
VO
LMT89
Any logic
device output
Figure 8. Conserving Power Dissipation With Shutdown
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System Examples (continued)
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
problems for analog output devices, such as the LMT89 and many op amps. The cause of this difficulty 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 ADCs 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 device.
V+ (+5.0V)
1k
1
0.1 PF
LM4040BIM3-4.1
4
5
3
470
GND
NC
6
3
VIN
V+
VO
LMT89
2
GND
1
V+
5
4
0.1 PF
2
CS
DO
CLK
ADCV0831
GND
Figure 9. Suggested Connection to a Sampling Analog-to-Digital Converter Input Stage
9 Power Supply Recommendations
The LMT89 device has a very wide 2.4-V to 5.5-V power supply voltage range making it 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 LMT89 device can be applied easily in the same way as other integrated-circuit temperature sensors. It can
be glued or cemented to a surface. The temperature that the LMT89 device is sensing will be within about
0.02°C of the surface temperature to which the leads of the LMT89 device are attached.
This 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 LMT89 die is directly attached to the pin 2 GND pin.
The temperatures of the lands and traces to the other leads of the LMT89 will also affect the temperature that is
being sensed.
Alternatively, the LMT89 device 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 LMT89 device 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
Humiseal and epoxy paints or dips are often used to ensure that moisture cannot corrode the LMT89 or its
connections.
12
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Layout Guidelines (continued)
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. Equation 13 is used to calculate the rise in the die temperature.
TJ = TA + RθJA [(V+ IQ) + (V+ − VO) IL]
where
•
IQ is the quiescent current and ILis the load current on the output. Because the junction temperature of the
LMT89 is the actual temperature being measured, take care to minimize the load current that the LMT89
device is required to drive.
(13)
Table 4 summarizes the rise in die temperature of the LMT89 device (without any loading), and the thermal
resistance for different conditions.
Table 4. Temperature Rise of LMT89 Due to Self-Heating and Thermal Resistance (RJΘA) (1)
SC70-5
SC70-5
NO HEAT SINK
SMALL HEAT SINK
RθJA
(°C/W)
TJ − TA
(°C)
RθJA
(°C/W)
TJ − TA
(°C)
Still air
412
0.2
350
0.19
Moving air
312
0.17
266
0.15
(1)
See Layout Examples for PCB layout samples.
10.2 Layout Example
NC
GND
GND
Vo
V+
Figure 10. Layout Used for No Heat Sink Measurements
NC
GND
GND
NC
Vo
V+
Figure 11. Layout Used for Measurements With Small Heat Sink
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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.
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PACKAGE OPTION ADDENDUM
www.ti.com
10-Dec-2020
PACKAGING INFORMATION
Orderable Device
Status
(1)
Package Type Package Pins Package
Drawing
Qty
Eco Plan
(2)
Lead finish/
Ball material
MSL Peak Temp
Op Temp (°C)
Device Marking
(3)
(4/5)
(6)
LMT89DCKR
ACTIVE
SC70
DCK
5
3000
RoHS & Green
SN
Level-1-260C-UNLIM
-55 to 130
T3B
LMT89DCKT
ACTIVE
SC70
DCK
5
250
RoHS & Green
SN
Level-1-260C-UNLIM
-55 to 130
T3B
(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
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