The 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 . For other part options, contact a Texas Instruments Distributor or Sales Representative for information on minimum order qualification. The LM27 is currently available in a 5-lead SOT-23 package.
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|Operating temperature range (C)|
|Accuracy over temp range (Max) (C)|
|Sensor Gain (mV/Deg C)|
|SetPoint Value (deg C)|
|Supply Voltage (Min) (V)|
|Supply Voltage (Max) (V)|
|Supply Current (Typ) (uA)|
|Comparator channels (#)|
|Package size: mm2:W x L (PKG)|
|120 to 150|
Range (120 to 150)
120, 130, 140
Hysteresis (2°C or 10°C)
Temperature Sensor and Switch
|SOT-23 | 5|
|5SOT-23: 8 mm2: 2.8 x 2.9 (SOT-23 | 5)|