Texas Instruments | LMT88 2.4-V, 10-µA, SC-70 Temperature Sensor (Rev. A) | Datasheet | Texas Instruments LMT88 2.4-V, 10-µA, SC-70 Temperature Sensor (Rev. A) Datasheet

Texas Instruments LMT88 2.4-V, 10-µA, SC-70 Temperature Sensor (Rev. A) Datasheet
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LMT88
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LMT88 2.4-V, 10-µA, SC-70 Temperature Sensor
1 Features
3 Description
•
•
•
•
•
The LMT88 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 LMT88 is
predominately linear, yet has a slight predictable
parabolic curvature. The accuracy of the LMT88
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
Disk Drives
Automotive
Portable Medical Instruments
Computers
Battery Management
Printers
Power Supply Modules
FAX Machines
Mobile Phones
Automotive
The LMT88 quiescent current is less than 10 μA.
Therefore, self-heating is less than 0.02°C in still air.
Shutdown capability for the LMT88 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 LMT88 is a cost-competitive alternative to
thermistors.
Device Information(1)
PART NUMBER
LMT88
PACKAGE
BODY SIZE (NOM)
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
+2.4V to +5.5V
Output Voltage vs Temperature
To MCU ADC
V+
VO
LMT88
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.
LMT88
SNIS175A – 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
6
Absolute Maximum Ratings ......................................
ESD Ratings..............................................................
Recommended Operating Conditions.......................
Thermal Information ..................................................
Electrical Characteristics...........................................
Typical Characteristics ..............................................
Detailed Description .............................................. 7
7.1 Overview ................................................................... 7
7.2 Functional Block Diagram ......................................... 7
7.3 Feature Description................................................... 7
7.4 Device Functional Modes.......................................... 8
8
Application and Implementation .......................... 9
8.1 Application Information.............................................. 9
8.2 Typical Applications ................................................ 10
8.3 System Examples ................................................... 13
9 Power Supply Recommendations...................... 13
10 Layout................................................................... 14
10.1 Layout Guidelines ................................................. 14
10.2 Layout Example .................................................... 14
10.3 Thermal Considerations ........................................ 14
11 Device and Documentation Support ................. 16
11.1 Trademarks ........................................................... 16
11.2 Electrostatic Discharge Caution ............................ 16
11.3 Glossary ................................................................ 16
12 Mechanical, Packaging, and Orderable
Information ........................................................... 16
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
DCK Package
5-Pin SOT
Top View
V+
4
3
VO
LMT88
5
2
GND
1
GND
NC
Pin Functions
PIN
NAME
NO.
TYPE
DESCRIPTION
NC
1
—
NC (pin 1) must be left floating or grounded. Other signal traces must not be connected to
this pin.
GND
2
GND
Device substrate and die attach paddle, connect to power supply negative terminal. For
optimum thermal conductivity to the PCB ground plane, pin 2 must be grounded. This pin
may also be left floating.
VO
3
Analog
Output
Temperature sensor analog output
V+
4
Power
Positive power supply pin
GND
5
GND
Device ground pin, connect to power supply negative terminal.
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6 Specifications
6.1 Absolute Maximum Ratings
(1) (2)
See
.
Supply Voltage
MIN
MAX
UNIT
−0.2
6.5
V
+
Output Voltage
(V + 0.6
V)
−0.6 V
Output Current
Input Current at any pin
(3)
Maximum Junction Temperature (TJMAX)
−65
Storage temperature (Tstg)
(1)
(2)
(3)
10
mA
5
mA
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
V(ESD)
(1)
(2)
Electrostatic discharge
Human-body model (HBM), per ANSI/ESDA/JEDEC JS-001 (1)
±2500
Charged-device model (CDM), per JEDEC specification JESD22C101 (2)
±250
UNIT
V
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
LMT88 with 2.4 V ≤ V+≤ 2.7 V Temperature Range
−30
130
°C
LMT88 with 2.7 V ≤ V+≤ 5.5 V Temperature Range
−55
130
°C
2.4
5.5
V
Supply Voltage Range (V+)
6.4 Thermal Information
LMT88
THERMAL METRIC
(1)
DCK
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 LMT88 please 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.
MIN (1)
TYP (2)
MAX (1)
TA= 25°C to 30°C
-4.0
±1.5
4.0
°C
TA = 130°C
-5.0
5.0
°C
TA = 125°C
-5.0
5.0
°C
TA = 100°C
-4.7
±4.7
°C
TA = 85°C
-4.6
4.6
°C
TA = 80°C
-4.5
4.5
°C
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
PARAMETER
Temperature to Voltage Error when using:
VO = (−3.88×10−6×T2) + (−1.15×10−2×T) +
1.8639 V (3)
TEST CONDITIONS
Output Voltage at 0°C
Variance from Curve
Non-Linearity
(4)
–20°C ≤ TA ≤ 80°C
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
0 μA ≤ IL ≤ 16 μA
Load Regulation (7)
Sourcing IL 0 μA to 16 μA
Line Regulation (8)
Change of Quiescent Current
−12.6
(1)
(2)
(3)
(4)
(5)
(6)
(7)
(8)
V
±1.0
°C
−11.77
(5) (6)
−11.0
mV/°C
160
Ω
−2.5
mV
2.4 V ≤ V+ ≤ 5.0 V
3.7
mV/V
5.0 V ≤ V+ ≤ 5.5 V
11
mV
7
μA
(5) (6)
+
4.5
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
2.4 V ≤ V+ ≤ 5.5 V
0.7
μA
−11
nA/°C
0.02
μA
Temperature Coefficient of Quiescent
Current
Shutdown Current
1.8639
±0.4%
2.4 V ≤ V+ ≤ 5.0 V; TA = 25°C
Quiescent Current
UNIT
+
V ≤ 0.8 V
Limits are specified to TI's AOQL (Average Outgoing Quality Level).
Typicals 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 LMT88 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.
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6.6 Typical Characteristics
8
MIN
MAX
Median
6
Accuracy (ƒC)
4
2
0
±2
±4
±6
±8
±60 ±40 ±20
0
20
40
60
80
100 120 140 160
DUT Temperature (ƒC)
C001
Figure 1. Temperature Sensor Accuracy
6
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7 Detailed Description
7.1 Overview
The LMT88 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 LMT88 is predominately linear, yet has a slight predictable parabolic curvature. The accuracy of the LMT88
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 LMT88 quiescent current is less than 10 μA. Therefore, self-heating is less than 0.02°C in still air. Shutdown
capability for the LMT88 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 LMT88 Transfer Function
The LMT88 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.
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Feature Description (continued)
VO = (−3.88×10−6×T2) + (−1.15×10−2×T) + 1.8639
(2)
solving for T:
1481.96 2.1962 u 10 6 T
(1.8639 VO )
3.88 u 10
6
(3)
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:
T
1481.96 2.1962 u 106 (1.8639 VO
3.88 u 10
6
(4)
For other methods of calculating T see Detailed Design Procedure.
7.4 Device Functional Modes
The LMT88's only functional mode is that it has an analog output inversely proportional to temperature.
8
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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 LMT88 has 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 LMT88 handles capacitive loading well. Without any precautions, the LMT88 can drive any capacitive load
less than 300 pF, as shown in Figure 2. Over the specified temperature range the LMT88 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 adding 0.1 μF from V+ to GND to bypass the power supply voltage, as shown in
Figure 3. 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 3. 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 LMT88 is much
slower, the overall response time of the LMT88 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.
+
LMT88
Heavy Capacitive Load, Wiring, Etc.
To A High-Impedance Load
OUT
d
Figure 2. LMT88 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
1k
0.001
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spacer between the table and graphic
+
LMT88
0.1 µF Bypass
Optional
Heavy Capacitive Load, Wiring, Etc.
OUT
d
R
C
+
Heavy Capacitive Load, Wiring, Etc.
R
LMT88
0.1 µF Bypass
Optional
OUT
d
C
Figure 3. LMT88 With Filter for Noisy Environment and Capacitive Loading Greater Than 300 pF
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
LMT88
GND
NC
Figure 4. Full-Range Celsius (Centigrade) Temperature Sensor (−55°C to 130°C)
8.2.1.1 Design Requirements
Because the LMT88 is a simple temperature sensor that provides an analog output, design requirements related
to layout are important, refer to Layout for detailed description.
8.2.1.2 Detailed Design Procedure
The LMT88 output follows Equation 5.
VO = (−3.88×10−6×T2) + (−1.15×10−2×T) + 1.8639
10
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Typical Applications (continued)
Solving for T:
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 LMT88. Equation 6 is the most accurate
equation that can be used to calculate the temperature of the LMT88.
(6)
An alternative to the quadratic equation a second order transfer function can be determined using "least squares"
method:
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.
(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 LMT88. The slope of the linear transfer function can be calculated using the following 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. For example for the temperature range of
TMIN = −30 to TMAX = 100°C:
(8)
T = 35°C
(9)
and
m = −11.77 mV/°C
(10)
The offset of the linear transfer function can be calculated using the following 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)
Using this procedure, the best fit linear transfer function for many popular temperature ranges was calculated in
Table 3. As shown in Table 3, the error that is 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
±0.65
Tmin (°C)
Tmax (°C)
−55
−40
-40
85
VO = −11.67 mV/°C × T + 1.8583 V
−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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8.2.1.3 Application Curve
Figure 5. Output Voltage vs Temperature
8.2.2 Centigrade Thermostat
V+
R3
R4
LM4040
V+
VT
R1
4.1V
U3
0.1 PF
LMT88
R2
(High = overtemp alarm)
+
U1
-
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 the following equations.
(4.1)R2
R2 + R1||R3
(12)
(4.1)R2||R3
VT2 =
R1 + R2||R3
(13)
VT1 =
12
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8.2.2.3 Application Curve
VTEMP
VT1
VT2
VOUT
Figure 7. Thermostat Output Waveform
8.3 System Examples
The LMT88 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
LMT88
Any logic
device output
Figure 8. Conserving Power Dissipation With Shutdown
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 LMT88 and many operational amplifiers. 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.
V+ (+5.0V)
1k
1
0.1 PF
LM4040BIM3-4.1
4
5
3
V+
VO
LMT88
2
GND
GND
NC
1
470 Ÿ
V+
6
3
VIN
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 LMT88 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.
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10 Layout
10.1 Layout Guidelines
The LMT88 can be applied easily in the same way as other IC temperature sensors. The device can be glued or
cemented to a surface. The temperature that the LMT88 is sensing will be within about 0.02°C of the surface
temperature to which the leads of LMT88 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 LMT88 die is directly attached to the pin 2 GND pin.
The temperatures of the lands and traces to the other leads of the LMT88 will also affect the temperature that is
being sensed.
Alternatively, the LMT88 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 LMT88 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 LMT88 or its connections.
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
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 LMT88, Equation 14 is used to calculate the rise in the die
temperature:
TJ = TA + θJA [(V+ IQ) + (V+ − VO) IL]
where
•
IQ is the quiescent current and ILis the load current on the output.
(14)
Because the junction temperature of the LMT88 is the actual temperature being measured, take care to minimize
the load current that the LMT88 is required to drive.
14
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Thermal Considerations (continued)
Table 4 summarizes the rise in die temperature of the LMT88 without any loading, and the thermal resistance for
different conditions.
Table 4. Temperature Rise of LMT88 Due to Self-Heating and Thermal Resistance (θJA) (1)
SC70-5
SC70-5
NO HEAT SINK
SMALL HEAT SINK
θJA
(°C/W)
TJ − TA
(°C)
θJA
(°C/W)
TJ − TA
(°C)
Still air
412
0.2
350
0.19
Moving air
312
0.17
266
0.15
(1)
See for samples.
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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.
16
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PACKAGE OPTION ADDENDUM
www.ti.com
29-Sep-2014
PACKAGING INFORMATION
Orderable Device
Status
(1)
Package Type Package Pins Package
Drawing
Qty
Eco Plan
Lead/Ball Finish
MSL Peak Temp
(2)
(6)
(3)
Op Temp (°C)
Device Marking
(4/5)
LMT88DCKR
ACTIVE
SC70
DCK
5
3000
Green (RoHS
& no Sb/Br)
CU SN
Level-1-260C-UNLIM
-55 to 130
T9C
LMT88DCKT
ACTIVE
SC70
DCK
5
250
Green (RoHS
& no Sb/Br)
CU SN
Level-1-260C-UNLIM
-55 to 130
T9C
(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)
Eco Plan - The planned eco-friendly classification: Pb-Free (RoHS), Pb-Free (RoHS Exempt), or Green (RoHS & no Sb/Br) - please check http://www.ti.com/productcontent for the latest availability
information and additional product content details.
TBD: The Pb-Free/Green conversion plan has not been defined.
Pb-Free (RoHS): TI's terms "Lead-Free" or "Pb-Free" mean semiconductor products that are compatible with the current RoHS requirements for all 6 substances, including the requirement that
lead not exceed 0.1% by weight in homogeneous materials. Where designed to be soldered at high temperatures, TI Pb-Free products are suitable for use in specified lead-free processes.
Pb-Free (RoHS Exempt): This component has a RoHS exemption for either 1) lead-based flip-chip solder bumps used between the die and package, or 2) lead-based die adhesive used between
the die and leadframe. The component is otherwise considered Pb-Free (RoHS compatible) as defined above.
Green (RoHS & no Sb/Br): TI defines "Green" to mean Pb-Free (RoHS compatible), and free of Bromine (Br) and Antimony (Sb) based flame retardants (Br or Sb do not exceed 0.1% by weight
in homogeneous material)
(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.
(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/Ball Finish - Orderable Devices may have multiple material finish options. Finish options are separated by a vertical ruled line. Lead/Ball Finish 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.
Addendum-Page 1
Samples
PACKAGE OPTION ADDENDUM
www.ti.com
29-Sep-2014
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.
Addendum-Page 2
PACKAGE MATERIALS INFORMATION
www.ti.com
29-Sep-2014
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
LMT88DCKR
SC70
DCK
5
3000
178.0
8.4
2.25
2.45
1.2
4.0
8.0
Q3
LMT88DCKT
SC70
DCK
5
250
178.0
8.4
2.25
2.45
1.2
4.0
8.0
Q3
Pack Materials-Page 1
PACKAGE MATERIALS INFORMATION
www.ti.com
29-Sep-2014
*All dimensions are nominal
Device
Package Type
Package Drawing
Pins
SPQ
Length (mm)
Width (mm)
Height (mm)
LMT88DCKR
SC70
DCK
5
3000
210.0
185.0
35.0
LMT88DCKT
SC70
DCK
5
250
210.0
185.0
35.0
Pack Materials-Page 2
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