LMT88DCKT

Sample & Buy Product Folder Support & Community Tools & Software Technical Documents LMT88 SNIS175A – MARCH 2013 – REVISED JANUARY 2015 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 www.ti.com 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 Submit Documentation Feedback Copyright © 2013–2015, Texas Instruments Incorporated Product Folder Links: LMT88 LMT88 www.ti.com SNIS175A – MARCH 2013 – REVISED JANUARY 2015 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. Submit Documentation Feedback Copyright © 2013–2015, Texas Instruments Incorporated Product Folder Links: LMT88 3 LMT88 SNIS175A – MARCH 2013 – REVISED JANUARY 2015 www.ti.com 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. Submit Documentation Feedback Copyright © 2013–2015, Texas Instruments Incorporated Product Folder Links: LMT88 LMT88 www.ti.com SNIS175A – MARCH 2013 – REVISED JANUARY 2015 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. Submit Documentation Feedback Copyright © 2013–2015, Texas Instruments Incorporated Product Folder Links: LMT88 5 LMT88 SNIS175A – MARCH 2013 – REVISED JANUARY 2015 www.ti.com 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 Submit Documentation Feedback Copyright © 2013–2015, Texas Instruments Incorporated Product Folder Links: LMT88 LMT88 www.ti.com SNIS175A – MARCH 2013 – REVISED JANUARY 2015 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. Submit Documentation Feedback Copyright © 2013–2015, Texas Instruments Incorporated Product Folder Links: LMT88 7 LMT88 SNIS175A – MARCH 2013 – REVISED JANUARY 2015 www.ti.com 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 Submit Documentation Feedback Copyright © 2013–2015, Texas Instruments Incorporated Product Folder Links: LMT88 LMT88 www.ti.com SNIS175A – MARCH 2013 – REVISED JANUARY 2015 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 Submit Documentation Feedback Copyright © 2013–2015, Texas Instruments Incorporated Product Folder Links: LMT88 9 LMT88 SNIS175A – MARCH 2013 – REVISED JANUARY 2015 www.ti.com 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 Submit Documentation Feedback (5) Copyright © 2013–2015, Texas Instruments Incorporated Product Folder Links: LMT88 LMT88 www.ti.com SNIS175A – MARCH 2013 – REVISED JANUARY 2015 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 Submit Documentation Feedback Copyright © 2013–2015, Texas Instruments Incorporated Product Folder Links: LMT88 11 LMT88 SNIS175A – MARCH 2013 – REVISED JANUARY 2015 www.ti.com 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 Submit Documentation Feedback Copyright © 2013–2015, Texas Instruments Incorporated Product Folder Links: LMT88 LMT88 www.ti.com SNIS175A – MARCH 2013 – REVISED JANUARY 2015 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. Submit Documentation Feedback Copyright © 2013–2015, Texas Instruments Incorporated Product Folder Links: LMT88 13 LMT88 SNIS175A – MARCH 2013 – REVISED JANUARY 2015 www.ti.com 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 Submit Documentation Feedback Copyright © 2013–2015, Texas Instruments Incorporated Product Folder Links: LMT88 LMT88 www.ti.com SNIS175A – MARCH 2013 – REVISED JANUARY 2015 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. Submit Documentation Feedback Copyright © 2013–2015, Texas Instruments Incorporated Product Folder Links: LMT88 15 LMT88 SNIS175A – MARCH 2013 – REVISED JANUARY 2015 www.ti.com 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 Submit Documentation Feedback Copyright © 2013–2015, Texas Instruments Incorporated Product Folder Links: LMT88 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) LMT88DCKR ACTIVE SC70 DCK 5 3000 RoHS & Green SN Level-1-260C-UNLIM -55 to 130 T9C LMT88DCKT ACTIVE SC70 DCK 5 250 RoHS & Green 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) 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