July 2008 LM26 SOT-23, ±3°C Accurate, Factory Preset Thermostat
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LM26 SOT-23, ±3°C Accurate, Factory Preset Thermostat
July 2008
LM26 SOT-23, ±3°C Accurate, Factory Preset Thermostat
LM26 precision, single digital-output, low-power thermostat comprised internal reference, DAC, temperature sensor comparator. Utilizing factory programming, manufactured with different trip points well different digital output functionality. trip point (TOS) preset factory temperature range -55°C +110°C increments. LM26 digital output (OS/OS/US/US), digital input (HYST) analog output (VTEMP). digital output stage preset either open-drain push-pull. addition, factory programmed active HIGH LOW. digital output factory programmed indicate over temperature shutdown event under temperature shutdown event US). When preset overtemperature shutdown (OS) will indicate that temperature over internally preset HIGH when temperature goes below (TOS-THYST). Similarly, when preprogrammed undertemperature shutdown (US) will HIGH indicate that temperature below when temperature above (TUS+THYST). typical hysteresis, THYST, 10°C controlled state HYST pin. VTEMP analog output provides voltage that proportional temperature -10.82mV/°C output slope. Available parts detailed ordering information. other part options, contact National Semiconductor Distributor Sales Representative information minimum order qualification. LM26 currently available 5-lead SOT-23 package.
Control Industrial Process Control HVAC Systems Remote Temperature Sensing Electronic System Protection
Features
Internal comparator with programmable 10°C
hysteresis
external components required Open Drain push-pull digital output; supports CMOS
logic levels Internal temperature sensor with VTEMP output VTEMP output allows after-assembly system testing Internal voltage reference trip-point setting Currently available 5-pin SOT-23 plastic package Excellent power supply noise rejection Recognized Component
Specifications
Power Supply Voltage Power Supply Current Hysteresis Temperature
Temperature Range -55°C +110°C +120°C 2.7V 5.5V 40µA(max) 20µA(typ) 10°C(typ)
Temperature Trip Point Accuracy LM26CIM ±3°C (max) ±4°C (max)
Applications
Microprocessor Thermal Management Appliances Portable Battery Powered Systems
LM26CIM5-TPA Simplified Block Diagram Connection Diagram
10132301
LM26CIM5-TPA fixed trip point 85°C. other trip point output function availability, please ordering information contact National Semiconductor.
2008 National Semiconductor Corporation
101323
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LM26
Ordering Information
more detailed information suffix meaning part number template Electrical Characteristics Section. Contact National Semiconductor other points output options. Order Number Bulk Rail LM26CIM5-DPB LM26CIM5-HHD LM26CIM5-NPA LM26CIM5-PHA LM26CIM5-RPA LM26CIM5-SHA LM26CIM5-SPA LM26CIM5-TPA LM26CIM5-VHA LM26CIM5-VPA LM26CIM5-XHA LM26CIM5-XPA LM26CIM5-YHA LM26CIM5-YPA LM26CIM5-ZHA 3000 Units Tape Reel LM26CIM5X-DPB LM26CIM5X-HHD LM26CIM5X-NPA LM26CIM5X-PHA LM26CIM5X-RPA LM26CIM5X-SHA LM26CIM5X-SPA LM26CIM5X-TPA LM26CIM5X-VHA LM26CIM5X-VPA LM26CIM5X-XHA LM26CIM5X-XPA LM26CIM5X-YHA LM26CIM5X-YPA LM26CIM5X-ZHA Mark TDPB THHD TNPA TPHA TRPA TSHA TSPA TTPA TVHA TVPA TXHA TXPA TYHA TYPA TZHA MA05B MA05B MA05B MA05B MA05B MA05B MA05B MA05B MA05B MA05B MA05B MA05B MA05B MA05B MA05B -25°C 45°C 50°C 65°C 70°C 75°C 85°C 90°C 95°C 100°C 105°C 110°C 115°C 120°C Open Drain Push Pull Open Drain Open Drain Open Drain Open Drain Open Drain Open Drain Open Drain Open Drain Open Drain Open Drain Open Drain Open Drain Open Drain Package Number Trip Point Setting Output Function
Connection Diagram
10132302
Descriptions
Number Name HYST VTEMP Function Hysteresis control, digital input Ground, connected back side through lead frame. Analog output voltage proportional temperature Supply input Overtemperature Shutdown open-drain active thermostat digital output Overtemperature Shutdown push-pull active high thermostat digital output Connection 10°C System Leave floating connect high impedance node. 2.7V 5.5V with 0.1µF bypass capacitor. PSRR information Section Titled NOISE CONSIDERATIONS. Controller interrupt, system power supply shutdown; pull-up resistor Controller interrupt, system power supply shutdown
Undertemperature Shutdown open-drain active System power supply shutdown; pull-up resistor thermostat digital output Undertemperature Shutdown push-pull active high thermostat digital output System power supply shutdown
Note: functionality trip point setting programmed during LM26 manufacture.
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LM26
Absolute Maximum Ratings (Note
Input Voltage Input Current (Note Package Input Current(Note Package Dissipation 25°C (Note Soldering Information SOT23 Package Vapor Phase seconds) Infrared seconds) 6.0V 20mA 500mW
Storage Temperature Susceptibility (Note Human Body Model Machine Model
-65°C 150°C 2500V 250V (Note -55°C +125°C TMIN TMAX +2.7V +5.5V +5.5V
Operating Ratings
Specified Temperature Range LM26CIM Positive Supply Voltage (V+) Maximum VOUT
215°C 220°C
LM26 Electrical Characteristics
following specifications apply 2.7VDC 5.5VDC, VTEMP load current unless otherwise specified. Boldface limits apply TMIN TMAX; other limits 25°C unless otherwise specified. Symbol Temperature Sensor Trip Point Accuracy (Includes VREF, DAC, -55°C +110°C Comparator Offset, Temperature +120°C Sensitivity errors) Trip Point Hysteresis VTEMP Output Temperature Sensitivity VTEMP Temperature Sensitivity Error Equation: 1.8015V -30°C 120°C, 2.7V HYST HYST -10.82 (max) (max) mV/°C (max) Parameter Conditions Typical (Note LM26CIM Limits (Note Units (Limits)
5.5V
-55°C 120°C, 4.5V 5.5V 30°C
(max)
±2.5 0.070 -0.2
(max) (max) mV/V
VTEMP Load Regulation VTEMP Line Regulation Supply Current
Source Sink +2.7V
+5.5V, -30°C +120°C
(max) (max) (max) (max)
Digital Output Input IOUT("1") VOUT("0") Logical Output Leakage Current (Note Logical Output Voltage +5.0V IOUT +1.2mA VOUT("1") Logical Push-Pull Output Voltage 0.001
V+4.5V; (Note
2.7V; IOUT +3.2mA
(min) (min) (min) (max)
ISOURCE 500µA, 2.7V ISOURCE 800µA,
4.5V
HYST Input Logical Threshold Voltage HYST Input Logical Threshold Voltage
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LM26
Note Absolute Maximum Ratings indicate limits beyond which damage device occur. Operating Ratings indicate conditions which device functional, guarantee specific performance limits. guaranteed specifications test conditions, Electrical Characteristics. guaranteed specifications apply only test conditions listed. Some performance characteristics degrade when device operated under listed test conditions. Note When input voltage (VI) exceeds power supply V+), current that should limited 5mA. 20mA maximum package input current rating limits number pins that safely exceed power supplies with input current four. Under normal operating conditions maximum current that pins handle limited each. Note maximum power dissipation must derated elevated temperatures dictated TJmax (maximum junction temperature), (junction ambient thermal resistance) (ambient temperature). maximum allowable power dissipation temperature (TJmax-TA)/JA number given Absolute Maximum Ratings, whichever lower. this device, TJmax 150°C. this device typical thermal resistance (JA) different package types when board mounted follow:
Package Type SOT23-5, MA05B
250°C/W
Note human body model 100pF capacitor discharge through 1.5k resistor into each pin. machine model 200pF capacitor discharged directly into each pin. Note other recommendations methods soldering surface mount devices. Note Typicals 25°C represent most likely parametric norm. Note Limits guaranteed National's AOQL (Average Outgoing Quality Level). Note Care should taken include effects self heating when setting maximum output load current. power dissipation LM26 would increase 1.28mW when IOUT=3.2mA VOUT=0.4V. With thermal resistance 250°C/W, this power dissipation would cause increase temperature about 0.32°C self heating. Self heating included trip point accuracy specification. Note limit based testing limitation does reflect actual performance part. Expect doubling current every 15°C increase temperature. example, typical current 25°C would increase 16nA 85°C.
Part Number Template
series digits labeled part number LM26CIM-xyz, describe point value function output follows: place holders describe point temperature shown following table. (10x) (1x) Temperature (°C) (10x) Open-Drain/ PushPull (1x) Temperature (°C)
value describes assignment/function output shown following table: Active-Low/High example: part number LM26CIM5-TPA 85°C, programmed active-low open-drain overtemperature shutdown output. part number LM26CIM5-FPD -5°C, programmed active-high, push-pull undertemperature shutdown output. OS/US Value Digital Output Function Active-Low, Open-Drain, output Active-Low, Open-Drain, output Active-High, Push-Pull, output Active-High, Push-Pull, output
Active-high open-drain active-low push-pull options available, please contact National Semiconductor more information.
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LM26
Functional Description
LM26 OPTIONS
10132312
10132313
LM26-_
LM26-_
10132314
10132315
LM26-_ FIGURE Output Options Block Diagrams LM26 factory programmed have trip point anywhere range -55°C +110°C.
LM26-_
Applications Hints
AFTER-ASSEMBLY TESTING LM26's VTEMP output allows after-assembly testing following simple test procedure. Simply measuring VTEMP output voltage will verify that LM26 been assembled properly that temperature sensing circuitry functional. VTEMP output very weak drive capability that overdriven 1.5mA. Therefore, simply force VTEMP voltage cause digital output change state, thereby verifying that comparator output circuitry function after assembly. Here sample test procedure that used test LM26CIM5-TPA which 85°C trip point. Turn measure VTEMP. Then calculate temperature reading LM26 using equation: -30)) 1.8015V Verify that temperature measured step within (±3°C error reference temperature sensor) ambient/board temperature. ambient/board temperature (reference temperature) should measured using extremely accurate calibrated temperature sensor.
Observe that high. Drive VTEMP ground. Observe that low. Release VTEMP pin. Observe that high. Observe that high. Drive VTEMP voltage down gradually. When goes low, note VTEMP voltage. VTEMPTrig VTEMP trigger (HIGH->LOW) Calculate Ttrig using Equation Gradually raise VTEMP until goes HIGH. Note VTEMP. Calculate THYST using Equation
VTEMP LOADING VTEMP output very weak drive capability source, sink). care should taken when attaching circuitry this pin. Capacitive loading cause VTEMP output oscillate. Simply adding resistor series shown Figure will prevent oscillations from occurring. determine value resistor follow guidelines given Table same value resistor will work either placement resistor. additional capacitive load placed directly LM26 output, rather than across CLOAD, should least factor smaller than CLOAD.
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LM26
TABLE Resistive compensation capacitive loading VTEMP CLOAD 8200 3000 1000
100pF
10nF 100nF
10132317
series with capacitor
mented surface. temperature that LM26 sensing will within about +0.06°C surface temperature which LM26's leads attached This presumes that ambient temperature almost same surface temperature; temperature were much higher lower than surface temperature, actual temperature measured would intermediate temperature between surface temperature temperature. ensure good thermal conductivity, backside LM26 directly attached (pin temperatures lands traces other leads LM26 will also affect temperature that being sensed. Alternatively, LM26 mounted inside sealed-end metal tube, then dipped into bath screwed into threaded hole tank. with LM26 accompanying wiring circuits must kept insulated dry, avoid leakage corrosion. This especially true circuit operate cold temperatures where condensation occur. Printed-circuit coatings varnishes such Humiseal epoxy paints dips often used ensure that moisture cannot corrode LM26 connections. junction ambient thermal resistance (JA) parameter used calculate rise part's junction temperature power dissipation. LM26 equation used calculate rise junction temperature follows: where ambient temperature, power supply voltage, quiescent current, IL_TEMP load current VTEMP output, voltage digital output, load current digital output. Since LM26's junction temperature actual temperature being measured, care should taken minimize load current that LM26 required drive. tables shown Figure summarize thermal resistance different conditions rise temperature LM26 without loading VTEMP pull-up resistor open-drain digital output with 5.5V power supply. SOT23-5 heat sink (°C/W) Still Moving TJ-TA (°C) 0.11 SOT23-5 small heat sink (°C/W) TJ-TA (°C)
10132318
series with signal path FIGURE Resistor placement capacitive loading compensation VTEMP NOISE CONSIDERATIONS LM26 excellent power supply noise rejection. Listed below variety signals used test LM26 power supply rejection. False triggering output observed when these signals where coupled into LM26. square wave 400kHz, 1Vp-p square wave 2kHz, 200mVp-p sine wave 100Hz 1MHz, 200mVp-p Testing done while maintaining temperature LM26 degree centigrade from trip point with output activated. MOUNTING CONSIDERATIONS LM26 applied easily same other integrated-circuit temperature sensors. glued
FIGURE Thermal resistance (JA) temperature rise self heating (TJ-TA)
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LM26
Typical Applications
10132303
Note: fan's control internal pull-up. pull-down sets slow speed. When output LM26 goes low, will speed
FIGURE Speed Speed Control
10132320
FIGURE High Side Drive
10132321
FIGURE Side Drive
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LM26
10132322
FIGURE Audio Power Amplifier Thermal Protection
10132323
FIGURE Simple Thermostat
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LM26
Physical Dimensions inches (millimeters) unless otherwise noted
5-Lead Molded SOT-23 Plastic Package, JEDEC Order Number LM26CIM5 LM26CIM5X Package Number MA05B
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LM26 SOT-23, ±3°C Accurate, Factory Preset Thermostat
Notes
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