Features: `Internal comparator with pin selectable 2 or 10 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
`Currently available in 5-pin SOT-23 plastic package
`Excellent power supply noise rejectionApplication·Microprocessor Thermal Management
·Appliances
·Portable Battery Powered Systems
·Fan Control
·Industrial Process Control
·HVAC Systems
·Electronic System Protection
Pinout
Specifications
| SetPoint Type |
Fixed |
| SetPoint Value |
130, 120, 140 deg C |
| Temperature Accuracy (+/-) |
3 deg C |
| Supply Min |
2.7 Volt |
| Temperature Min |
120 deg C |
| Temperature Max |
150 deg C |
| Quiescent Current_ |
40 uA |
| Comparators |
1 |
| Sensor Gain |
-10.82 mV/Deg C |
| Remote Diode Thermal Sensors |
Undefined |
| Supply Max |
5.5 Volt |
| VtempOutput Impedance |
18 Ohm |
| Quiescent Current |
0.04 mA |
| AEC Q-100 Automotive Grade |
0 |
| Automotive Selection Guide |
Yes |
| PowerWise |
Yes |
| View Using Catalog |
Input Voltage 6.0V
Input Current at any pin (Note 2) 5mA
Package Input Current(Note 2) 20mA
Package Dissipation at TA = 25
(Note 3) 500mW
Soldering Information
SOT23 Package
Vapor Phase (60 seconds) 215
Infrared (15 seconds) 220
Storage Temperature -65 to + 150
ESD Susceptibility (Note 4)
Human Body Model 2500V
Machine Model 250VDescriptionThe LM27 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 LM27 has one digital output (OS/OS#/US/US#), one digital input (HYST) and one analog output (VTEMP). The digital output stage can be preset as either open-drain or push-pull. In addition, it can be factory programmed to be active HIGH or LOW. The digital output can be factory programmed to indicate an over temperature shutdown event (OS or OS#) or an under temperature shutdown event (US or US#). When preset as an overtemperature shutdown (OS#) it will go LOW to indicate that the die temperature is over the internally preset TOS and go HIGH when the temperature goes below (TOS-THYST). Similarly, when preprogrammed as an undertemperature shutdown (US) it will go HIGH to indicate that the temperature is below TUS and go LOW 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. A VTEMP analog output provides a voltage that is proportional to temperature and has a -10.7mV/°C output slope.
Currently, there are several standard parts available, see ordering information for details. For other part options, contact a National Semiconductor Distributor or Sales Representative for information on minimum order qualification. The LM27 is currently available in a 5-lead SOT-23 package.
Reliability Metrics
| Part Number |
Process |
EFR Reject |
EFR Sample Size |
PPM |
LTA Rejects |
LTA Device Hours |
FITS |
MTTF (Hours) |
| LM27-2PL MDA |
CMOS7 |
0 |
16561 |
0 |
0 |
954000 |
4 |
270700104 |
| LM27CIM5-1HJ |
CMOS7 |
0 |
16561 |
0 |
0 |
954000 |
4 |
270700104 |
| LM27CIM5-2HJ |
CMOS7 |
0 |
16561 |
0 |
0 |
954000 |
4 |
270700104 |
| LM27CIM5-ZHJ |
CMOS7 |
0 |
16561 |
0 |
0 |
954000 |
4 |
270700104 |
Note: The Early Failure Rates (EFR) were calculated as point estimate PPM based on rejects and sample size for EFR. The Long Term Failure Rates were calculated at 60% confidence using the Arrhenius equation at 0.7eV activation energy and derating the assumed stress temperature of 150°C to an application temperature of 55°C.For more information on Reliability Metrics, please click here.
More Application Notes
| Title |
Size in Kbytes |
Date |
|
| AN-1256: Application Note 1256 Tiny Temperature Sensors for Portable Systems |
66 Kbytes |
1-Oct-02 |
Download |
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|
LM27 Data Sheet
