LM27A ±3°C Accurate, 120°C-150°C Factory Preset Thermostat (LM27 in Die Form) General Description This datasheet applies to the LM27A, which is the die form of the LM27. The LM27 is available in the SOT23-5 package. Please refer to the LM27 datasheet for detailed specifications pertaining to the packaged part. The LM27A is a precision, single digital-output, low-power thermostat comprised of an internal reference, DAC, temperature sensor and comparator. Utilizing factory programming, it can be manufactured with different trip points as well as different digital output functionality. The trip point (TOS) can be preset at the factory to any temperature in the range of +120°C to +150°C in 1°C increments. The LM27A has two digital output pads, one digital input (HYST) and one analog output (VTEMP). One digitial output is an active-high, push-pull output and the other is an active-low, open-drain output. Either of the outputs (but not both) are available. The LM27A is available in either an overtemperature shutdown or an undertemperature shutdown option. An LM27A with overtemperature shutdown is configured so that its thermostat outputs (OS and OS) will go active when a rising temperature crosses the trip point and the hysteresis will apply to a falling temperature. The thermostat outputs of an LM27A with an undertemperature shutdown (US and US) will trip on a falling temperature and hysteresis will apply on a rising temperature. For example, when the LM27A is preset as an overtemperature shutdown, the active-high output (OS) will go HIGH and the active-low output (OS) will go LOW to indicate that the die temperature is over the internally preset TOS . The outputs will reset to their normal states when the temperature goes below (TOS–THYST). Similarly, when preprogrammed as an undertemperature shutdown the activehigh output (US) will go HIGH and the active-low output (US) will go LOW to indicate that the temperature is below TUS . The outputs will reset when the temperature is above (TUS+THYST). The typical hysteresis, THYST, can be set to 2°C or 10°C and is controlled by the state of the HYST pin. The VTEMP analog output provides a voltage that is proportional to temperature and has a −10.7mV/°C output slope. © 2007 National Semiconductor Corporation 201530 Standard parts are available, see ordering information for details. For other part options, contact a National Semiconductor Distributor or Sales Representative for information on minimum-order qualification. Applications ■ ■ ■ ■ ■ ■ ■ Microprocessor Thermal Management Appliances Portable Battery Powered Systems Fan Control Industrial Process Control HVAC Systems Electronic System Protection Features ■ Internal comparator with pin selectable 2°C or 10°C hysteresis ■ No external components required ■ Open-drain or push-pull digital output; supports CMOS ■ ■ ■ ■ ■ logic levels Internal temperature sensor with VTEMP output pin VTEMP output allows after-assembly system testing Internal voltage reference and DAC for trip-point setting Excellent power supply noise rejection AEC-Q100 Qualified Key Specifications ■ Power Supply Voltage 2.7V to 5.5V ■ Power Supply Current 40µA(max) 15µA(typ) ■ Hysteresis Temperature ■ Temperature Trip Point Accuracy 2°C or 10°C(typ) ±3°C (max) www.national.com LM27A SOT-23, ±3°C Accurate, 120°C-150°C Factory Preset Thermostat (LM27 in Die Form) July 2007 LM27A Ordering Information For more detailed information on the suffix meaning see the part number template at the end of the Electrical Characteristics Section. Contact National Semiconductor for other set points and output options. Order Number LM27-2PL MDA NS Package Number Trip Point Setting Output Function Transport Media Die form, no package 145°C Push-Pull (OS) Open-Drain (OS) 400 units in waffle trays Connection Diagram LM27A Bond Pad Layout 20153002 TOP VIEW 1130µm x 902µm Bond Pad Mechanical Dimensions Dimensions of bond pad coordinates are in micrometers. Origin of coordinates: center of die. X-Direction is in the longitudinal axis of the die. Coordinates refer to center of Bond Pad. Opening sizes for bond pads 1 through 6 are 85 µm × 85 µm. Pin# X Y 1 –437 µm +225 µm 2 –437 µm 0 3 –437 µm –220 µm 4 +437 µm –220 µm 5 +437 µm +5 µm 6 +437 µm +225 µm BACK www.national.com 2 LM27A Pin Descriptions Pin Number Pin Name 1 HYST 2 (Note 8) 3 (Note 8) 4 Function Connection Hysteresis control, digital input GND for 10°C or V+ for 2°C OS Overtemperature Shutdown pushpull active-high thermostat digital output Controller interrupt, system or power supply shutdown US Undertemperature Shutdown pushpull active-high thermostat digital output System or power supply shutdown OS Overtemperature Shutdown opendrain active-low thermostat digital output Controller interrupt, system or power supply shutdown; US Undertemperature Shutdown opendrain active low thermostat digital output System or power supply shutdown; pull-up resistor ≥ 10kΩ V+ Supply input 2.7V to 5.5V with a 0.1µF bypass capacitor. For PSRR information see Section Titled NOISE CONSIDERATIONS. System ground pull-up resistor ≥ 10kΩ 5 GND Power supply ground 6 VTEMP Analog output voltage proportional to Leave floating or connect to a high impedance node. temperature 7 - 14 NC Do not connect BACK Backside Can go to GND connection (Note: GND must be connected. The back is not a system ground connection). Note: Only connect to one of the output pads, Pad 2 or Pad 3, not both. Either push-pull (Pad 2) or open-drain (Pad 3) can be used but they can not both be used on the same die. 3 www.national.com LM27A Absolute Maximum Ratings (Note 1) Input Voltage Input Current at any pin (Note 2) Package Input Current(Note 2) Storage Temperature ESD Susceptibility (Note 3) Human Body Model Machine Model Operating Ratings 6.0V 5mA 20mA −65°C to + 175°C (Note 1) TMIN ≤ TA ≤ TMAX Specified Temperature Range −40°C ≤ TA ≤ +150°C LM27A Positive Supply Voltage (V+) Maximum VOUT +2.7V to +5.5V +5.5V 2500V 250V LM27A Electrical Characteristics The following specifications apply for V+ = 2.7VDC to 5.5VDC, and VTEMP load current = 0µA unless otherwise specified. Boldface limits apply for TA = TJ = TMIN to TMAX; all other limits TA = TJ = 25°C unless otherwise specified. Symbol Parameter Conditions Typical (Note 4) LM27A Limits Units (Limits) (Note 5) Temperature Sensor Trip Point Accuracy (Includes VREF, DAC, +120°C<TA<+150°C Comparator Offset, and Temperature Sensitivity errors) Trip Point Hysteresis HYST = GND HYST = V+ VTEMP Output Temperature Sensitivity VTEMP Temperature Sensitivity Error to Equation: VO = (−3.552×10−6×(T−30)2+ (−10.695×10−3×(T−30))+ 1.8386V VTEMP Load Regulation ±3 10 2.7V ≤ 2 °C mV/°C 4.5V ≤ Source ≤ 1 μA IS +2.7V ≤ °C (max) ±3 °C (max) ±2.5 °C (max) ≤ 5.5V TA = 25°C 0.070 Sink ≤ 40 μA VTEMP Line Regulation ±3 ≤ 5.5V −55°C ≤ TA ≤ 150°C, V+ °C −10.82 −30°C ≤ TA ≤ 150°C, V+ °C (max) ≤ +5.5V, −30°C ≤ TA ≤ +120°C V+ Supply Current mV mV (max) 0.7 −0.2 mV/V 15 22 40 µA (max) µA (max) 0.001 1 µA (max) 0.4 V (max) ISOURCE = 500µA, V+ ≥ 2.7V 0.8 × V+ V (min) ISOURCE = 800µA, V+≥4.5V V+ − 1.5 V (min) V+ V (min) Digital Output and Input IOUT(“1”) Logical “1” Output Leakage Current (Note V+ = +5.0V 7) VOUT(“0”) Logical “0” Output Voltage IOUT = +1.2mA and ≥2.7V; IOUT = +3.2mA V+ and V+≥4.5V; (Note 6) VOUT(“1”) Logical “1” Push-Pull Output Voltage VIH HYST Input Logical ”1“ Threshold Voltage 0.8 × VIL HYST Input Logical ”0“ Threshold Voltage 0.2 × V+ V (max) tEN tENABLE: Time from Power-On to Digital Output (OS or OS) Enabled 350 µs (min) www.national.com VDD = 3.3V ±5% 4 LM27A Definition of tENABLE 20153024 Note 1: Absolute Maximum Ratings indicate limits beyond which damage to the device may occur. Operating Ratings indicate conditions for which the device is functional, but do not guarantee specific performance limits. For guaranteed specifications and test conditions, see the Electrical Characteristics. The guaranteed specifications apply only for the test conditions listed. Some performance characteristics may degrade when the device is not operated under the listed test conditions. Note 2: When the input voltage (VI) at any pin exceeds the power supply (VI < GND or VI > V+), the current at that pin should be limited to 5mA. The 20mA maximum package input current rating limits the number of pins that can safely exceed the power supplies with an input current of 5mA to four. Under normal operating conditions the maximum current that pins 2, 4 or 5 can handle is limited to 5mA each. Note 3: The human body model is a 100pF capacitor discharge through a 1.5kΩ resistor into each pin. The machine model is a 200pF capacitor discharged directly into each pin. Note 4: Typicals are at TJ = TA = 25°C and represent most likely parametric norm. Note 5: Limits are guaranteed to National's AOQL (Average Outgoing Quality Level). Note 6: Care should be taken to include the effects of self heating when setting the maximum output load current. Self heating is not included in the trip point accuracy specification. Note 7: The 1µA limit is based on a testing limitation and does not reflect the actual performance of the part. Expect to see a doubling of the current for every 15°C increase in temperature. For example, the 1nA typical current at 25°C would increase to 16nA at 85°C. Note 8: Only connect to one of the output pads, number 2 or number 3, not both. Either push-pull (Pad 2) or open-drain (Pad 3) can be used but they can not both be used on the same die. Part Number Template The series of digits labeled xyz in the part number LM27-xyz MDA, describe the set point value and the function of the output as follows: The place holders xy describe the set point temperature as shown in the following table. x (10x) x (10x) y (1x) Temperature (°C) y (1x) Temperature (°C) - H 0 - S 7 - J 1 - T 8 - K 2 - V 9 - L 3 Z - 12 - N 4 1 - 13 - P 5 2 - 14 - R 6 3 - 15 The value of z describes the assignment/function of the output as shown in the following table: Value of z Digital Output Function L Overtemperature shutdown: active-high OS output or active-low OS output N Undertemperature shutdown: active-high US or active-low US output. For example: • • The part number LM27-2SL MDA would have TOS = 147°C, and is programmed as an overtemperature shutdown output. The part number LM27-ZLN MDA would have TUS = 123°C, and is programmed as an undertemperature shutdown output. Active-high open-drain and active-low push-pull options are available, please contact National Semiconductor for more information. 5 www.national.com LM27A same value resistor will work for either placement of the resistor. If an additional capacitive load is placed directly on the LM27A output, rather than across CLOAD, it should be at least a factor of 10 smaller than CLOAD. Applications Hints AFTER-ASSEMBLY PCB TESTING The LM27A's VTEMP output allows after-assembly PCB testing by following a simple test procedure. Simply measuring the VTEMP output voltage will verify that the LM27A has been assembled properly and that its temperature sensing circuitry is functional. The VTEMP output has very weak drive capability that can be overdriven by 1.5mA. Therefore, one can simply force the VTEMP voltage to cause the digital output to change state, thereby verifying that the comparator and output circuitry function after assembly. Here is a sample test procedure that can be used to test a part that would have the part number LM27-2HJ MDA, which would have a 140°C trip point. 1. Turn on V+ and measure VTEMP. Then calculate the temperature reading of the LM27A using the equation: VO = (−3.552×10−6×(T−30)2) + (−10.69576×10−3×(T−30)) + 1.8386V TABLE 1. Resistive compensation for capacitive loading of VTEMP CLOAD R (Ω) ≤100pF 0 1nF 8200 10nF 3000 100nF 1000 ≥1µF 430 (1) or 2. (2) Verify that the temperature measured in step one is within (±3°C + error of reference temperature sensor) of the ambient/board temperature. The ambient/board temperature (reference temperature) should be measured using an extremely accurate calibrated temperature sensor, which is in close proximity to and mounted on the same PCB as the LM27A perhaps even touching the GND lead of the LM27A if possible. The LM27A will sence the board temperature not the ambient temperature. 20153017 a) R in series with capacitor 3. A. Observe that OS is high. B. Drive VTEMP to ground. C. Observe that OS is now low. D. Release the VTEMP pin. E. Observe that OS is now high. 4. 20153018 A. B. C. D. E. Observe that OS is high. Drive VTEMP voltage down gradually. When OS goes low, note the VTEMP voltage. VTEMPTrig = VTEMP at OS trigger (HIGH->LOW) Calculate Ttrig using Equation 2. A. Gradually raise VTEMP until OS goes HIGH. Note VTEMP. Calculate THYST using Equation 2. b) R in series with signal path FIGURE 1. Resistor placement for capacitive loading compensation of VTEMP NOISE CONSIDERATIONS The LM27A has excellent power supply noise rejection. Listed below is a variety of signals used to test the LM27A power supply rejection. False triggering of the output was not observed when these signals where coupled into the V+ pin of the LM27A. • square wave 400kHz, 1Vp-p • square wave 2kHz, 200mVp-p • sine wave 100Hz to 1MHz, 200mVp-p Testing was done while maintaining the temperature of the LM27A one degree centigrade way from the trip point with the output not activated. 5. B. VTEMP LOADING The VTEMP output has very weak drive capability (1 µA source, 40 µA sink). So care should be taken when attaching circuitry to this pin. Capacitive loading may cause the VTEMP output to oscillate. Simply adding a resistor in series as shown in Figure 1 will prevent oscillations from occurring. To determine the value of the resistor follow the guidelines given in Table 1. The www.national.com 6 LM27A Typical Applications 20153003 Note: The fan's control pin has internal pull-up. The 10k pull-down sets a slow fan speed. When the output of the LM27A goes low, the fan will speed up. FIGURE 2. Two Speed Fan Speed Control 20153020 FIGURE 3. Fan High Side Drive 20153021 FIGURE 4. Fan Low Side Drive 7 www.national.com LM27A 20153022 FIGURE 5. Audio Power Amplifier Thermal Protection 20153023 FIGURE 6. Simple Thermostat Physical Dimensions for Die Product 20153002 Order Number LM27-2PL MDA Bare Die TOP VIEW 1130µm × 902µm For Bond Pad Mechanical Dimensions, see Connection Diagram Section www.national.com 8 LM27A 9 www.national.com LM27A SOT-23, ±3°C Accurate, 120°C-150°C Factory Preset Thermostat (LM27 in Die Form) Notes THE CONTENTS OF THIS DOCUMENT ARE PROVIDED IN CONNECTION WITH NATIONAL SEMICONDUCTOR CORPORATION (“NATIONAL”) PRODUCTS. NATIONAL MAKES NO REPRESENTATIONS OR WARRANTIES WITH RESPECT TO THE ACCURACY OR COMPLETENESS OF THE CONTENTS OF THIS PUBLICATION AND RESERVES THE RIGHT TO MAKE CHANGES TO SPECIFICATIONS AND PRODUCT DESCRIPTIONS AT ANY TIME WITHOUT NOTICE. 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As used herein: Life support devices or systems are devices which (a) are intended for surgical implant into the body, or (b) support or sustain life and whose failure to perform when properly used in accordance with instructions for use provided in the labeling can be reasonably expected to result in a significant injury to the user. A critical component is any component in a life support device or system whose failure to perform can be reasonably expected to cause the failure of the life support device or system or to affect its safety or effectiveness. National Semiconductor and the National Semiconductor logo are registered trademarks of National Semiconductor Corporation. All other brand or product names may be trademarks or registered trademarks of their respective holders. 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