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LMT01-Q1
SNIS192C – NOVEMBER 2016 – REVISED JUNE 2018
LMT01-Q1 0.5°C Accurate 2-Pin Digital Output Temperature Sensor With Pulse Count
Interface
1 Features
3 Description
•
The LMT01-Q1 device is a high-accuracy, 2-pin
temperature sensor with an easy-to-use pulse count
current loop interface, which makes it suitable for
onboard and offboard applications in automotive,
industrial, and consumer markets. The LMT01-Q1
digital pulse count output and high accuracy over a
wide temperature range allow pairing with any MCU
without concern for integrated ADC quality or
availability, while minimizing software overhead. TI’s
LMT01-Q1 device achieves a maximum ±0.5°C
accuracy with very fine resolution (0.0625°C) over a
temperature range of –20°C to 90°C without system
calibration or hardware and software compensation.
1
•
•
•
•
•
•
•
•
AEC-Q100 Qualified With the Following Results:
– Temperature Grade 0 (E): –40°C to +150°C (2)
– Temperature Grade 1 (Q): –40°C to +125°C
– HBM ESD Component Classification Level 2
– CDM ESD Component Classification Level C5
High Accuracy Over –40°C to 150°C Wide
Temperature Range
– –20°C to 90°C: ±0.5°C (Maximum)
– 90°C to 120°C: ±0.625°C (Maximum)
– –40°C to –20°C: ±0.625°C (Maximum)
Precision Digital Temperature Measurement
Simplified in a 2-Pin Package
Pulse Count Current Loop Easily Read by
Processor. Pulse Count Proportional to
Temperature With 0.0625°C Resolution
Communication Frequency: 88 kHz
Conversion Current: 34 µA
Continuous Temperature Update Every 100 ms
Floating 2-V to 5.5-V (VP–VN) Supply Operation
With Integrated EMI Immunity
Multiple 2-Pin Package Offerings: TO-92/LPG (3.1
mm × 4 mm × 1.5 mm) – ½ the Size of Traditional
TO-92 and WSON With Wettable Flanks
The LMT01-Q1’s pulse count interface is designed to
directly interface with a GPIO or comparator input,
thereby
simplifying
hardware
implementation.
Similarly,
the
LMT01-Q1's
integrated
EMI
suppression and simple 2-pin architecture makes it
suitable for onboard and offboard temperature
sensing in a noisy environment. The LMT01-Q1
device can be easily converted into a two-wire
temperature probe with a wire length up to two
meters.
Device Information(1)
PART NUMBER
PACKAGE
BODY SIZE (NOM)
LMT01QLPG
TO-92 (2)
4.00 mm × 3.15 mm
LMT01ELPG
TO-92 (2)
4.00 mm × 3.15 mm
2 Applications
LMT01QDQX
WSON (2)
1.70 mm × 2.50 mm
•
(1) For all available packages, see the orderable addendum at
the end of the data sheet.
(2) Applicable only for the LPG package.
•
•
•
Automotive
– Battery Management Systems
– Engine Management and ADAS
Digital Output Wired Probes
HVAC
Power Supplies and Battery Management
2-Pin IC Temperature Sensor
VDD: 3.0V to 5.5V
GPIO
Up to 2m
VP
LMT01-Q1 Accuracy
Min 2.0V
LMT01
MCU/
FPGA/
ASIC
1.0
VN
Temperature Accuracy (ƒC)
0.8
Max Limit
GPIO/
COMP
0.6
0.4
LMT01 Pulse Count Interface
0.2
Conversion Time
ADC Conversion Result
0.0
Power Off
-0.2
Power On
-0.4
-0.6
Min Limit
-0.8
-1.0
±50
±25
0
25
50
75
100
LMT01 Junction Temperaure (ƒC)
125
150
C014
Typical units plotted in center of curve.
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.
LMT01-Q1
SNIS192C – NOVEMBER 2016 – REVISED JUNE 2018
www.ti.com
Table of Contents
1
2
3
4
5
6
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
Absolute Maximum Ratings ...................................... 4
ESD Ratings.............................................................. 4
Recommended Operating Conditions ...................... 4
Thermal Information .................................................. 4
Electrical Characteristics........................................... 5
Electrical Characteristics - TO-92/LPG Pulse Count
to Temperature LUT................................................... 6
6.7 Electrical Characteristics - WSON/DQX Pulse Count
to Temperature LUT................................................... 6
6.8 Switching Characteristics .......................................... 7
6.9 Timing Diagram......................................................... 7
6.10 Typical Characteristics ............................................ 8
7
Detailed Description ............................................ 11
7.2 Functional Block Diagram ....................................... 11
7.3 Feature Description................................................. 11
7.4 Device Functional Modes........................................ 14
8
Application and Implementation ........................ 15
8.1 Application Information............................................ 15
8.2 Typical Application .................................................. 16
8.3 System Examples .................................................. 18
9 Power Supply Recommendations...................... 20
10 Layout................................................................... 21
10.1 Layout Guidelines ................................................. 21
10.2 Layout Example .................................................... 21
11 Device and Documentation Support ................. 22
11.1
11.2
11.3
11.4
11.5
Receiving Notification of Documentation Updates
Community Resources..........................................
Trademarks ...........................................................
Electrostatic Discharge Caution ............................
Glossary ................................................................
22
22
22
22
22
12 Mechanical, Packaging, and Orderable
Information ........................................................... 22
7.1 Overview ................................................................. 11
4 Revision History
Changes from Revision B (June 2017) to Revision C
Page
•
Added device stamp to the TO-92 pinout top view ................................................................................................................ 3
•
Changed the TO-92S pin numbers in the Pin Functions........................................................................................................ 3
Changes from Revision A (April 2017) to Revision B
Page
•
Removed Electrical Characteristics: WSON/DQX table; Combined the LPG and DQX Electrical Characteristics
tables together ........................................................................................................................................................................ 5
•
Changed IOL maximum value from: 39 µA to: 40 µA .............................................................................................................. 5
•
Changed leakage value from: 1 µA to 3.5 µA ........................................................................................................................ 5
•
Moved the thermal response time parameters to the Electrical Characteristics table ........................................................... 5
•
Added Missing Cross References ........................................................................................................................................ 11
Changes from Original (November 2016) to Revision A
Page
•
Added new WSON/DQX package throughout data sheet ..................................................................................................... 1
•
Changed updated package information. ................................................................................................................................ 3
•
Added Electrical Characteristics - WSON/DQX Pulse Count to Temperature LUT ............................................................... 6
•
Added -40 for Sample Calculations Table ........................................................................................................................... 12
•
Added missing cross reference ........................................................................................................................................... 13
2
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SNIS192C – NOVEMBER 2016 – REVISED JUNE 2018
5 Pin Configuration and Functions
DQX Package
2-Pin WSON
Bottom View
VP
VN
LPG Package
2-Pin TO-92
Top View
LM
YM
LL
F
T0
1
VN
VP
Pin Functions
PIN
NAME
TO-92S
WSON
VP
2
1
VN
1
2
TYPE
Input
DESCRIPTION
Positive voltage pin; may be connected to system power supply or bias resistor.
Output Negative voltage pin; may be connected to system ground or a bias resistor.
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SNIS192C – NOVEMBER 2016 – REVISED JUNE 2018
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6 Specifications
6.1 Absolute Maximum Ratings
(1) (2)
See
.
MIN
MAX
UNIT
Voltage drop (VP – VN)
−0.3
6
V
Storage temperature, Tstg
−65
175
°C
(1)
(2)
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 Reflow Temperature Profile specifications. Refer to www.ti.com/packaging.
6.2 ESD Ratings
VALUE
V(ESD)
(1)
Electrostatic discharge
Human-body model (HBM), per AEC Q100-002 (1)
±2000
Charged-device model (CDM), per AEC Q100-011
±750
UNIT
V
AEC Q100-002 indicates that HBM stressing shall be in accordance with the ANSI/ESDA/JEDEC JS-001 specification.
6.3 Recommended Operating Conditions
MIN
MAX
UNIT
Free-air temperature(LPG)
-40
150
°C
Free-air temperature (DQX)
–40
125
°C
Voltage drop (VP – VN)
2 (1)
5.5
V
(1)
During transmission of pulses at a high level.
6.4 Thermal Information
LMT01-Q1
THERMAL METRIC (1)
DQX (WSON)
LPG (TO-92)
2 PINS
2 PINS
UNIT
177
°C/W
RθJA
Junction-to-ambient thermal resistance
213
RθJC(top)
Junction-to-case (top) thermal resistance
71
94
°C/W
RθJB
Junction-to-board thermal resistance
81
152
°C/W
ψJT
Junction-to-top characterization parameter
2.4
33
°C/W
ψJB
Junction-to-board characterization parameter
79
152
°C/W
(1)
4
For more information about traditional and new thermal metrics, see the Semiconductor and IC Package Thermal Metrics application
report.
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6.5 Electrical Characteristics
Over operating free-air temperature range and operating VP-VN range (unless otherwise noted).
PARAMETER
TEST CONDITIONS
MIN
150°C (3)
125°C
TYP
MAX
UNIT
–0.75
0.75
°C
-0.75
0.75
°C
120°C
–0.625
0.625
°C
110°C
–0.5625
0.5625
°C
100°C
VP – VN of
2.15 V to 5.5 V 90°C
–0.5625
0.5625
°C
–0.5
0.5
°C
25°C
–0.5
0.5
°C
–20°C
–0.5
0.5
°C
–30°C
–0.5625
0.5625
°C
–40°C
–0.625
0.625
°C
ACCURACY
Temperature accuracy
(1) (2)
±0.125
PULSE COUNT TRANSFER FUNCTION
Number of pulses at 0°C
800
Output pulse range
Theoretical max (exceeds
device rating)
808
816
15
3228
1
4095
Resolution of one pulse
0.0625
°C
OUTPUT CURRENT
IOL
IOH
Output current variation
Low level
28
34
40
µA
High level
112.5
125
143
µA
3.1
3.7
4.5
40
133
m°C/V
0.002
3.5
µA
High-to-Low level output current ratio
POWER SUPPLY
Accuracy sensitivity to change in VP – VN
2.15 V ≤ VP – VN ≤ 5. 0 V (4)
Leakage Current VP – VN
VDD ≤ 0.4 V
THERMAL RESPONSE
Stirred oil thermal response time to 63% of final value DQX (WSON)
(package only)
LPG (TO-92)
0.4
DQX (WSON)
9.4
LPG (TO-92)
28
Still air thermal response time to 63% of final value
(package only)
(1)
(2)
(3)
(4)
0.8
s
s
Calculated using Pulse Count to Temperature LUT and 0.0625°C resolution per pulse, see section Electrical Characteristics - TO92/LPG Pulse Count to Temperature LUT and Electrical Characteristics - WSON/DQX Pulse Count to Temperature LUT.
Error can be linearly interpolated between temperatures given in table as shown in the Accuracy vs Temperature curves in section
Typical Characteristics.
Applicable only for the LPG package.
Limit is using end point calculation.
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6.6 Electrical Characteristics - TO-92/LPG Pulse Count to Temperature LUT
Over operating free-air temperature range and 2.15 V ≤ VP – VN ≤ 5. 0 V power supply operating range (unless otherwise
noted). LUT is short for Look-up Table.
PARAMETER
Digital output code
MIN
TYP
MAX
–40°C
TEST CONDITIONS
172
181
190
–30°C
329
338
347
–20°C
486
494
502
–10°C
643
651
659
0°C
800
808
816
10°C
958
966
974
20°C
1117
1125
1133
30°C
1276
1284
1292
40°C
1435
1443
1451
50°C
1594
1603
1611
60°C
1754
1762
1771
70°C
1915
1923
1931
80°C
2076
2084
2092
90°C
2237
2245
2254
100°C
2398
2407
2416
110°C
2560
2569
2578
120°C
2721
2731
2741
130°C
2883
2894
2905
140°C
3047
3058
3069
150°C
3208
3220
3231
UNIT
pulses
6.7 Electrical Characteristics - WSON/DQX Pulse Count to Temperature LUT
Over operating free-air temperature range and 2.15 V ≤ VP – VN ≤ 5. 0 V power supply operating range (unless otherwise
noted). LUT is short for Look-up Table.
PARAMETER
Digital output code
6
TEST CONDITIONS
MIN
TYP
MAX
–40°C
172
181
190
–30°C
328
338
346
–20°C
486
494
502
–10°C
643
651
659
0°C
800
808
816
10°C
958
966
974
20°C
1117
1125
1133
30°C
1276
1284
1292
40°C
1435
1443
1451
50°C
1594
1602
1611
60°C
1754
1762
1771
70°C
1915
1923
1931
80°C
2076
2084
2092
90°C
2237
2245
2254
100°C
2398
2407
2416
110°C
2560
2569
2578
120°C
2721
2731
2741
125°C
2802
2814
2826
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UNIT
pulses
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6.8 Switching Characteristics
Over operating free-air temperature range and operating VP – VN range (unless otherwise noted).
PARAMETER
TEST CONDITIONS
tR, tF
Output current rise and fall time
fP
Output current pulse frequency
MIN
CL = 10 pF, RL = 8 k
Temperature conversion time (1)
tDATA
Data transmission time
(1)
MAX
UNIT
kHz
1.45
Output current duty cycle
tCONV
TYP
µs
82
88
94
40%
50%
60%
46
50
54
ms
44
47
50
ms
2.15 V to 5.5 V
Conversion time includes power up time or device turn on time that is typically 3 ms after POR threshold of 1.2 V is exceeded.
6.9 Timing Diagram
tCONV
tDATA
Power
125µA
34µA
tR
Power Off
Output
Current
tF
1/fP
Figure 1. Timing Specification Waveform
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6.10 Typical Characteristics
1.0
1.0
0.8
Max Limit
Temperature Accuracy (ƒC)
Temperature Accuracy (ƒC)
0.8
0.6
0.4
0.2
0.0
-0.2
-0.4
-0.6
Min Limit
-0.8
±25
0
25
50
75
100
125
LMT01 Junction Temperaure (ƒC)
0.0
-0.2
-0.4
-0.6
150
Min Limit
±50
±25
0
25
50
75
100
125
LMT01 Junction Temperaure (ƒC)
C017
Using Electrical Characteristics - TO-92/LPG Pulse Count to
Temperature LUT
VP – VN = 2.15 V
150
C016
Using Electrical Characteristics - TO-92/LPG Pulse Count to
Temperature LUT
VP – VN = 2.4 V
Figure 2. Accuracy vs LMT01-Q1 Junction Temperature
Figure 3. Accuracy vs LMT01-Q1 Junction Temperature
1.0
1.0
0.8
0.8
Max Limit
Temperature Accuracy (ƒC)
Temperature Accuracy (ƒC)
0.2
-1.0
±50
0.6
0.4
0.2
0.0
-0.2
-0.4
-0.6
Min Limit
-0.8
Max Limit
0.6
0.4
0.2
0.0
-0.2
-0.4
-0.6
Min Limit
-0.8
-1.0
-1.0
±50
±25
0
25
50
75
100
125
LMT01 Junction Temperaure (ƒC)
150
±50
±25
0
25
50
75
100
125
LMT01 Junction Temperaure (ƒC)
C015
Using Electrical Characteristics - TO-92/LPG Pulse Count to
Temperature LUT
VP – VN = 2.7 V
150
C014
Using Electrical Characteristics - TO-92/LPG Pulse Count to
Temperature LUT
VP – VN = 3 V
Figure 4. Accuracy vs LMT01-Q1 Junction Temperature
Figure 5. Accuracy vs LMT01-Q1 Junction Temperature
1.0
1.0
0.8
0.8
Max Limit
Temperature Accuracy (ƒC)
Temperature Accuracy (ƒC)
0.4
-0.8
-1.0
0.6
0.4
0.2
0.0
-0.2
-0.4
-0.6
Min Limit
-0.8
Max Limit
0.6
0.4
0.2
0.0
-0.2
-0.4
-0.6
Min Limit
-0.8
-1.0
-1.0
±50
±25
0
25
50
75
100
125
LMT01 Junction Temperaure (ƒC)
150
±50
Figure 6. Accuracy vs LMT01-Q1 Junction Temperature
±25
0
25
50
75
100
125
LMT01 Junction Temperaure (ƒC)
C013
Using Electrical Characteristics - TO-92/LPG Pulse Count to
Temperature LUT
VP – VN = 4 V
8
Max Limit
0.6
150
C012
Using Electrical Characteristics - TO-92/LPG Pulse Count to
Temperature LUT
VP – VN = 5 V
Figure 7. Accuracy vs LMT01-Q1 Junction Temperature
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Typical Characteristics (continued)
3.0
1.00
2.5
Max Limit
Temperature Accuracy (ƒC)
Temperature Accuracy (ƒC)
0.80
0.60
0.40
0.20
0.00
-0.20
-0.40
-0.60
1.0
0.5
0.0
-1.0
-1.00
±50
±25
0
25
50
75
100
125
±50
150
0
25
50
75
100
125
150
C018
C011
Using Electrical Characteristics - TO-92/LPG Pulse Count to
Temperature LUT
VP – VN = 5.5 V
Using Temp = (PC/4096 × 256°C ) – 50°C
VP – VN = 2.15 V
Figure 9. Accuracy Using Linear Transfer Function
Figure 8. Accuracy vs LMT01-Q1 Junction Temperature
3.0
150
2.5
125
Output Current (µA)
2.0
1.5
1.0
0.5
0.0
High Level Current
100
75
Low Level Current
50
25
-0.5
-1.0
0
±50
±25
0
25
50
75
100
125
LMT01 Junction Temperaure (ƒC)
150
2
3
4
5
VP - VN (V)
C019
Using Temp = (PC/4096 × 256°C ) – 50°C
VP – VN = 5.5V
6
C004
TA = 30°C
Figure 10. Accuracy Using Linear Transfer Function
Figure 11. Output Current vs VP-VN Voltage
150
Percent of (Final - Initial) Value (%)
110
125
Output Current (µA)
±25
LMT01 Junction Temperaure (ƒC)
LMT01 Junction Temperature (ƒC)
Temperature Accuracy (ƒC)
1.5
-0.5
Min Limit
-0.80
2.0
High Level Current
100
75
Low Level Current
50
25
0
100
90
80
70
60
50
40
30
20
10
0
±50
±25
0
25
50
75
100
125
LMT01 Juntion Temperature (ƒC)
150
0
120 240 360 480 600 720 840 960 1080 1200
Time (seconds)
C003
VP – VN = 3.3 V
TINITIAL = 23°C,
VP – VN = 3.3 V
Figure 12. Output Current vs Temperature
C033
TFINAL = 70°C
Figure 13. Thermal Response in Still Air (TO92S/LPG
Package)
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110
110
100
100
Percent of (Final - Initial) Value (%)
Percent of (Final - Initial) Value (%)
Typical Characteristics (continued)
90
80
70
60
50
40
30
20
10
0
80
70
60
50
40
30
20
10
0
0
20
40
60
80
100 120 140 160 180 200
Time (seconds)
VP – VN = 3.3 V
TINITIAL = 23°C,
TFINAL = 70°C
0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 6.0 6.5 7.0
Time (seconds)
C032
Air Flow = 2.34
meters/sec
Figure 14. Thermal Response in Moving Air (TO92S/LPG
Package)
10
90
VP – VN = 3.3 V
TINITIAL = 23°C,
C031
TFINAL = 70°C
Figure 15. Thermal Response in Stirred Oil (TO92S/LPG
Package)
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7 Detailed Description
7.1 Overview
The LMT01-Q1 temperature output is transmitted over a single wire using a train of current pulses that typically
change from 34 µA to 125 µA. A simple resistor can then be used to convert the current pulses to a voltage. With
a 10-kΩ resistor, the output voltage levels range from 340 mV to 1.25 V, typically. A simple microcontroller
comparator or external transistor can be used convert this signal to valid logic levels the microcontroller can
process properly through a GPIO pin. The temperature can be determined by gating a simple counter on for a
specific time interval to count the total number of output pulses. After power is first applied to the device the
current level will remain below 34 µA for at most 54 ms while the LMT01-Q1 is determining the temperature.
When the temperature is determined, the pulse train begins. The individual pulse frequency is typically 88 kHz.
The LMT01-Q1 will continuously convert and transmit data when the power is applied approximately every 104
ms (maximum).
The LMT01-Q1 uses thermal diode analog circuitry to detect the temperature. The temperature signal is then
amplified and applied to the input of a ΣΔ ADC that is driven by an internal reference voltage. The ΣΔ ADC
output is then processed through the interface circuitry into a digital pulse train. The digital pulse train is then
converted to a current pulse train by the output signal conditioning circuitry that includes high and low current
regulators. The voltage applied across the pins of the LMT01-Q1 is regulated by an internal voltage regulator to
provide a consistent Chip VDD that is used by the ADC and its associated circuitry.
7.2 Functional Block Diagram
VP
Chip VDD
Chip VSS
Thermal Diode
Analog Circuitry
Data
ADC
Interface
Voltage
Regulator
and
Output
Signal
Conditioning
VREF
LMT01
VN
7.3 Feature Description
7.3.1 Output Interface
The LMT01-Q1 provides a digital output in the form of a pulse count that is transmitted by a train of current
pulses. After the LMT01-Q1 is powered up, it transmits a very low current of 34 µA for less than 54 ms while the
part executes a temperature to digital conversion, as shown in Figure 16. When the temperature-to-digital
conversion is complete, the LMT01-Q1 starts to transmit a pulse train that toggles from the low current of 34 µA
to a high current level of 125 µA. The pulse train total time interval is at maximum 50 ms. The LMT01-Q1
transmits a series of pulses equivalent to the pulse count at a given temperature as described in Electrical
Characteristics - TO-92/LPG Pulse Count to Temperature LUT. After the pulse count has been transmitted the
LMT01-Q1 current level will remain low for the remainder of the 50 ms. The total time for the temperature to
digital conversion and the pulse train time interval is 104 ms (maximum). If power is continuously applied, the
pulse train output will repeat start every 104 ms (maximum).
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Feature Description (continued)
Start of data
transmission
Power
ON
End of data
54ms
max
Start of next
conversion result data
End of data
104ms max
Power
50ms max
50ms max
Power
Off
Pulse
Train
Figure 16. Temperature to Digital Pulse Train Timing Cycle
The LMT01-Q1 can be powered down at any time to conserve system power. Take care to ensure that a
minimum power-down wait time of 50 ms is used before the device is turned on again.
7.3.2 Output Transfer Function
TheLMT01-Q1 outputs at minimum 1 pulse and a theoretical maximum 4095 pulses. Each pulse has a weight of
0.0625°C. One pulse corresponds to a temperature less than –50°C while a pulse count of 4096 corresponds to
a temperature greater than 200°C. Note that the LMT01-Q1 is only ensured to operate up to 150°C. Exceeding
this temperature by more than 5°C may damage the device. The accuracy of the device degrades as well when
150°C is exceeded.
Two different methods of converting the pulse count to a temperature value are discussed in this section. The
first method is the least accurate and uses a first order equation, and the second method is the most accurate
and uses linear interpolation of the values found in the look-up table (LUT) as described in Electrical
Characteristics - TO-92/LPG Pulse Count to Temperature LUT.
The output transfer function appears to be linear and can be approximated by Equation 1:
§ PC
·
Temp ¨
u 256qC ¸ 50qC
© 4096
¹
where
•
•
PC is the Pulse Count
Temp is the temperature reading
(1)
Table 1 shows some sample calculations using Equation 1.
Table 1. Sample Calculations Using Equation 1
12
TEMPERATURE (°C)
NUMBER OF PULSES
–40
160
–20
480
0
800
30
1280
50
1600
100
2400
150
3200
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The curve shown in Figure 17 shows the output transfer function using equation Equation 1 (blue line) and the
look-up table (LUT) found in Electrical Characteristics - TO-92/LPG Pulse Count to Temperature LUT (red line).
The LMT01-Q1 output transfer function as described by the LUT appears to be linear, but upon close inspection,
it can be seen as truly not linear. To actually see the difference, the accuracy obtained by the two methods must
be compared.
4096
3584
Pulse Count
3072
2560
2048
1536
1024
512
0
±50 ±25
0
25
50
75
100 125 150 175 200 225
LMT01 Junction Temperature (ƒC)
C002
Figure 17. LMT01-Q1 Output Transfer Function
For more exact temperature readings the output pulse count can be converted to temperature using linear
interpolation of the values found in Electrical Characteristics - TO-92/LPG Pulse Count to Temperature LUT.
3.0
1.0
2.5
0.8
Temperature Accuracy (ƒC)
Temperature Accuracy (ƒC)
The curves in Figure 18 and Figure 19, show the accuracy of typical units when using the Equation 1 and linear
interpolation using Electrical Characteristics - TO-92/LPG Pulse Count to Temperature LUT, respectively. When
compared, the improved performance when using the LUT linear interpolation method can clearly be seen. For a
limited temperature range of 25°C to 80°C, the error shown in Figure 18 is flat, so the linear equation will provide
good results. For a wide temperature range, TI recommends that linear interpolation and the LUT be used.
2.0
1.5
1.0
0.5
0.0
-0.5
Max Limit
0.6
0.4
0.2
0.0
-0.2
-0.4
-0.6
Min Limit
-0.8
-1.0
-1.0
±50
±25
0
25
50
75
100
125
LMT01 Junction Temperaure (ƒC)
150
±50
Figure 18. LMT01-Q1 Typical Accuracy When Using First
Order Equation Equation 1 – 92 Typical Units Plotted at
(VP – VN) = 2.15 V
±25
0
25
50
75
100
LMT01 Junction Temperaure (ƒC)
C018
125
150
C017
Figure 19. LMT01-Q1 Accuracy Using Linear Interpolation
of LUT Found in Electrical Characteristics - WSON/DQX
Pulse Count to Temperature LUT – 92 Typical Units
Plotted at (VP – VN) = 2.15 V
7.3.3 Current Output Conversion to Voltage
The minimum voltage drop across the LMT01-Q1 must be maintained at 2.15 V during the conversion cycle.
After the conversion cycle, the minimum voltage drop can decrease to 2.0 V. Thus the LMT01-Q1 can be used
for low voltage applications. See Application Information for more information on low voltage operation and other
information on picking the actual resistor value for different applications conditions. The resistor value is
dependent on the power supply level and the variation and the threshold level requirements of the circuitry the
resistor is driving (that is, MCU, GPIO, or Comparator).
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Stray capacitance can be introduced when connecting the LMT01-Q1 through a long wire. This stray capacitance
influences the signal rise and fall times. The wire inductance has negligible effect on the AC signal integrity. A
simple RC time constant model as shown in Figure 20 can be used to determine the rise and fall times.
POWER
tHL
LMT01
VF
VHL
OUTPUT
C
100pF
34 and
125 µA
R
10k
VS
Figure 20. Simple RC Model for Rise and Fall Times
§ V VS ·
Ru Cu In ¨ F
¸
© VF VHL ¹
tHL
where
•
•
•
•
RC as shown in Figure 20
VHL is the target high level
the final voltage VF = 125 µA × R
the start voltage VS = 34 µA × R
(2)
For the 10% to 90% level rise time (tr), Equation 2 simplifies to:
tr = R×C×2.197
(3)
Take care to ensure that the LMT01-Q1 voltage drop does not exceed 300 mV under reverse bias conditions, as
given in the Absolute Maximum Ratings.
7.4 Device Functional Modes
The only functional mode the LMT01-Q1 has is that it provides a pulse count output that is directly proportional to
temperature.
14
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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
8.1.1 Mounting, Temperature Conductivity, and Self-Heating
The LMT01-Q1 can be applied easily in the same way as other integrated-circuit temperature sensors. It can be
glued or cemented to a surface to ensure good temperature conductivity. The temperatures of the lands and
traces to the leads of the LMT01-Q1 also affect the temperature reading, so they must be a thin as possible.
Alternatively, the LMT01-Q1 can be mounted inside a sealed-end metal tube, and then can be dipped into a bath
or screwed into a threaded hole in a tank. As with any IC, the LMT01-Q1 and accompanying wiring and circuits
must be kept insulated and dry to avoid excessive leakage and corrosion. Printed-circuit coatings are often used
to ensure that moisture cannot corrode the leads or circuit traces.
The junction temperature of the LMT01-Q1 is the actual temperature being measured by the device. The thermal
resistance junction-to-ambient (RθJA) is the parameter (from Thermal Information) used to calculate the rise of a
device junction temperature (self-heating) due to its average power dissipation. The average power dissipation of
the LMT01-Q1 is dependent on the temperature it is transmitting as it effects the output pulse count and the
voltage across the device. Equation 4 is used to calculate the self-heating in the die temperature of the LMT01Q1 (TSH).
ª§
tCONV
·
u VCONV ¸
ǬIOL u
t
t
CONV
DATA
¹
¬«©
TSH
§ ª§ PC
tDATA
·º
I
I · § 4096 PC
u OL OH ¸ ¨
u IOL ¸» u
¨ «¨
¨ © 4096
t
2
CONV tDATA
¹ © 4096
¹¼
©¬
º
·
¸ u VDATA » u RTJA
¸
¹
¼»
where
•
•
•
•
•
•
•
•
TSH is the ambient temperature
IOL and IOH are the output low and high current level, respectively
VCONV is the voltage across the LMT01-Q1 during conversion
VDATA is the voltage across the LMT01-Q1 during data transmission
tCONV is the conversion time
tDATA is the data transmission time
PC is the output pulse count
RθJA is the junction to ambient package thermal resistance
(4)
Plotted in the curve Figure 21 are the typical average supply current (black line using left y axis) and the resulting
self-heating (red and violet lines using right y axis) during continuous conversions. A temperature range of –50°C
to +150°C, a VCONV of 5 V (red line) and 2.15 V (violet line) were used for the self-heating calculation. As can be
seen in the curve, the average power supply current and thus the average self-heating changes linearly over
temperature because the number of pulses increases with temperature. A negligible self-heating of about 45m°C
is observed at 150°C with continuous conversions. If temperature readings are not required as frequently as
every 100 ms, self-heating can be minimized by shutting down power to the part periodically thus lowering the
average power dissipation.
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60
0.06
50
0.05
40
0.04
30
0.03
20
0.02
10
0.01
Average Current
Self Heating at VP-VN=5V
Self Heating at VP-VN=2.15V
0
-100
-50
0
50
100
150
Self Heating (ƒC)
Average Current (µA)
Application Information (continued)
0.00
200
Temperature (ƒC)
C001
Figure 21. Average Current Draw and Self-Heating Over Temperature
8.2 Typical Application
8.2.1 3.3-V System VDD MSP430 Interface - Using Comparator Input
VDD 3.3V
MSP430
GPIO
Divider
VREF
2.73V
or
2.24V
VP
LMT01
TIMER2
VN
COMP_B
CLOCK
+
VR
IR = 34
and 125 µA
R
6.81k
1%
Figure 22. MSP430 Comparator Input Implementation
8.2.1.1 Design Requirements
The design requirements listed in are used in the detailed design procedure.
Table 2. Design Parameters
DESIGN PARAMETER
EXAMPLE VALUE
VDD
3.3 V
VDD minimum
3.0 V
LMT01-Q1 VP – VN minimum during conversion
2.15 V
LMT01-Q1 VP – VN minimum during data
transmission
2.0 V
Noise margin
50 mV minimum
Comparator input current over temperature range
of interest
Resistor tolerance
16
< 1 uA
1%
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8.2.1.2 Detailed Design Procedure
First, select the R and determine the maximum logic low voltage and the minimum logic high voltage while
ensuring that when the LMT01-Q1 is converting, the minimum (VP – VN) requirement of 2.15 V is met.
1. Select R using minimum VP-VN during data transmission (2 V) and maximum output current of the LMT01Q1 (143.75 µA)
– R = (3.0 V – 2 V) / 143.75 µA = 6.993 k the closest 1% resistor is 6.980 k
– 6.993 k is the maximum resistance so if using 1% tolerance resistor the actual resistor value needs to be
1% less than 6.993 k and 6.98 k is 0.2% less than 6.993 k thus 6.81 k must be used.
2. Check to see if the 2.15-V minimum voltage during conversion requirement for the LMT01-Q1 is met with the
maximum IOL of 39 µA and maximum R of 6.81 k + 1%:
– VLMT01 = 3 V – (6.81 k × 1.01) × 39 µA = 2.73 V
3. Find the maximum low level voltage range using the maximum R of 6.81 k and maximum IOL of 39 µA:
– VRLmax = (6.81 k × 1.01) × 39 µA = 268 mV
4. Find the minimum high level voltage using the minimum R of 6.81 k and minimum IOH of 112.5 µA:
– VRHmin = (6.81 k × 0.99) × 112.5 µA = 758 mV
Now select the MSP430 comparator threshold voltage that enables the LMT01-Q1 to communicate to the
MSP430 properly.
1. The MSP430 voltage is selected by selecting the internal VREF and then choosing the appropriate 1 of n/32
settings for n of 1 to 31.
– VMID= (VRLmax – VRHmin) / 2 + VRHmin = (758 mV – 268 mV) / 2 + 268 mV = 513 mV
– n = (VMID / VREF ) × 32 = (0.513 / 2.5) × 32 = 7
2. To prevent oscillation of the comparator, output hysteresis must be implemented. The MSP430 allows this by
enabling different n for the rising edge and falling edge of the comparator output. For a falling comparator
output transition, N must be set to 6.
3. Determine the noise margin caused by variation in comparator threshold level. Even though the comparator
threshold level theoretically is set to VMID, the actual level varies from device to device due to VREF tolerance,
resistor divider tolerance, and comparator offset. For proper operation, the COMP_B worst case input
threshold levels must be within the minimum high and maximum low voltage levels presented across R,
VRHmin and VRLmax, respectively
N N_TOL
VCHmax VREF u 1 V_REF_TOL u
COMP_OFFSET
32
where
•
•
•
•
•
VCLmin
VREF is the MSP430 COMP_B reference voltage for this example at 2.5 V
V_REF_TOL is the tolerance of the VREF of 1% or 0.01,
N is the divisor for the MSP430 or 7
N_TOL is the tolerance of the divisor or 0.5
COMP_OFFSET is the comparator offset specification or 10 mV
VREF u 1 V_REF_TOL u
N N_TOL
32
(5)
COMP_OFFSET
where
•
•
•
•
•
VREF is the MSP430 COMP_B reference voltage for this example at 2.5 V,
V_REF_TOL is the tolerance of the VREF of 1% or 0.01,
N is the divisor for the MSP430 for the hysteresis setting or 6,
N_TOL is the tolerance of the divisor or 0.5,
COMP_OFFSET is the comparator offset specification or 10 mV
(6)
The noise margin is the minimum of the two differences:
(VRHmin – VCHmax) or (VCHmin – VRLmax)
(7)
which works out to be 145 mV.
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Comparator Threshold and VR
VDD
Pulse
Count
Signal
VRHmax
VRHmin
Noise Margin
VCHmax
VMID
VCHmin
Noise Margin
VRLmax
VRLmin
GND
Time (µs)
Figure 23. Pulse Count Signal Amplitude Variation
8.2.1.2.1 Setting the MSP430 Threshold and Hysteresis
The comparator hysteresis determines the noise level that the signal can support without causing the comparator
to trip falsely and resulting in an inaccurate pulse count. The comparator hysteresis is set by the precision of the
MSP430 and what thresholds it is capable of. For this case, as the input signal transitions high, the comparator
threshold is dropped by 77 mV. If the noise on the signal is kept below this level as it transitions, the comparator
will not trip falsely. In addition, the MSP430 has a digital filter on the COMP_B output that be used to further filter
output transitions that occur too quickly.
8.2.1.3 Application Curves
Amplitude = 200 mV/div
Time Base = 10 µs/div
Δy at cursors = 500 mV
Δx at cursors = 11.7 µs
Figure 24. MSP430 COMP_B Input Signal No Capacitance
Load
Amplitude = 200 mV/div
Time Base = 10 µs/div
Δy at cursors = 484 mV
Δx at cursors = 11.7 µs
Figure 25. MSP430 COMP_B Input Signal 100-pF
Capacitance Load
8.3 System Examples
The LMT01 device can be configured in a number of ways. Transistor level shifting can be used so that the
output pulse of the device can be read with a GPIO (see Figure 26). An isolation block can be inserted to
achieve electrical isolation (see Figure 27). Multiple LMT01 devices can be controlled with GPIOs enabling
temperature monitor for multiple zones. Lastly, the LMT01 device can be configured to have a common ground
with a high side signal (see Figure 29).
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System Examples (continued)
3.3V
VDD
MCU/
FPGA/
ASIC
VP
LMT01
100k
VN
GPIO
MMBT3904
34 and
125 µA
7.5k
Figure 26. Transistor Level Shifting
3V to 5.5V
3V to 5.5V
ISO734x
VCC1
VCC2
VDD
VP
ISOLATION
LMT01
MCU/FPGA/
ASIC
Min
2.0V
100k
VN
GPIO
MMBT3904
34 and
125 µA
7.5k
GND2
GND1
Figure 27. Isolation
VDD
3V to 5.5V
GPIO1
GPIO2
GPIO n
Up to 2.0m
VP
VP
VP
LMT01
U1
LMT01
U2
LMT01
Un
VN
VN
VN
MCU/FPGA/
ASIC
Min
2.0V
GPIO/
COMP
34 and
125 µA
6.81k
(for 3V)
Note: to turn off an LMT01-Q1 set the GPIO pin connected to VP to high impedance state as setting it low would
cause the off LMT01-Q1 to be reverse biased. Comparator input of MCU must be used.
Figure 28. Connecting Multiple Devices to One MCU Input Pin
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System Examples (continued)
3.3V
VDD
34 and
125 µA
7.5k
MCU/
FPGA/
ASIC
MMBT3906
VP
LMT01
GPIO
VN
100k
Note: the VN of the LMT01-Q1 must be connected to the MCU GND.
Figure 29. Common Ground With High-Side Signal
9 Power Supply Recommendations
Because the LMT01-Q1 is only a 2-pin device the power pins are common with the signal pins, thus the LMT01Q1 has a floating supply that can vary greatly. The LMT01-Q1 has an internal regulator that provides a stable
voltage to internal circuitry.
Take care to prevent reverse biasing of the LMT01-Q1 as exceeding the absolute maximum ratings may cause
damage to the device.
Power supply ramp rate can effect the accuracy of the first result transmitted by the LMT01-Q1. As shown in
Figure 30 with a 1-ms rise time, the LMT01-Q1 output code is at 1286, which converts to 30.125°C. The scope
photo shown in Figure 31 reflects what happens when the rise time is too slow. In Figure 31, the power supply
(yellow trace) is still ramping up to final value while the LMT01-Q1 (red trace) has already started a conversion.
This causes the output pulse count to decrease from the previously shown 1286, to 1282 (or 29.875°C). Thus,
for slow ramp rates, TI recommends that the first conversion be discarded. For even slower ramp rates, more
than one conversion may have to be discarded as TI recommends that either the power supply be within final
value before a conversion is used or that ramp rates be faster than 2.5 ms.
Yellow trace = 1 V/div, Red trace = 100 mV/div, Time Base = 20
ms/div
TA= 30°C
LMT01 Pulse Count = 1286
VP-VN = 3.3 V
Rise Time = 1 ms
Figure 30. Output Pulse Count With Appropriate Power
Supply Rise Time
20
Yellow trace = 1V/div, Red trace = 100 mV/div, Time base = 20
ms/div
TA=30°C
LMT01 Pulse Count = 1282
VP-VN=3.3 V
Rise Time = 100 ms
Figure 31. Output Pulse Count With Slow Power Supply
Rise Time
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10 Layout
10.1 Layout Guidelines
The LMT01-Q1 can be mounted to a PCB as shown in Figure 32 and Figure 33. Take care to make the traces
leading to the pads as small as possible to minimize their effect on the temperature the LMT01-Q1 is measuring.
10.2 Layout Example
VP
VN
Figure 32. Layout Example (TO92S/LPG Package)
VN
VP
Figure 33. Layout Example for the DQX (WSON) Package
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11 Device and Documentation Support
11.1 Receiving Notification of Documentation Updates
To receive notification of documentation updates, navigate to the device product folder on ti.com. In the upper
right corner, click on Alert me to register and receive a weekly digest of any product information that has
changed. For change details, review the revision history included in any revised document.
11.2 Community Resources
The following links connect to TI community resources. Linked contents are provided "AS IS" by the respective
contributors. They do not constitute TI specifications and do not necessarily reflect TI's views; see TI's Terms of
Use.
TI E2E™ Online Community TI's Engineer-to-Engineer (E2E) Community. Created to foster collaboration
among engineers. At e2e.ti.com, you can ask questions, share knowledge, explore ideas and help
solve problems with fellow engineers.
Design Support TI's Design Support Quickly find helpful E2E forums along with design support tools and
contact information for technical support.
11.3 Trademarks
E2E is a trademark of Texas Instruments.
All other trademarks are the property of their respective owners.
11.4 Electrostatic Discharge Caution
This integrated circuit can be damaged by ESD. Texas Instruments recommends that all integrated circuits be handled with
appropriate precautions. Failure to observe proper handling and installation procedures can cause damage.
ESD damage can range from subtle performance degradation to complete device failure. Precision integrated circuits may be more
susceptible to damage because very small parametric changes could cause the device not to meet its published specifications.
11.5 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
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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)
LMT01ELPGMQ1
ACTIVE
TO-92
LPG
2
3000
RoHS & Green
SN
N / A for Pkg Type
-40 to 150
T01G0
LMT01ELPGQ1
ACTIVE
TO-92
LPG
2
1000
RoHS & Green
SN
N / A for Pkg Type
-40 to 150
T01G0
LMT01QDQXRQ1
ACTIVE
WSON
DQX
2
3000
RoHS & Green
SN
Level-1-260C-UNLIM
-40 to 125
13M
LMT01QDQXTQ1
ACTIVE
WSON
DQX
2
250
RoHS & Green
Call TI
Level-1-260C-UNLIM
-40 to 125
13M
LMT01QLPGMQ1
ACTIVE
TO-92
LPG
2
3000
RoHS & Green
SN
N / A for Pkg Type
-40 to 125
T01G1
LMT01QLPGQ1
ACTIVE
TO-92
LPG
2
1000
RoHS & Green
SN
N / A for Pkg Type
-40 to 125
T01G1
(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