LM57

LM57 Resistor-Programmable Temperature Switch and Analog Temperature Sensor LM57 February 9, 2010 Resistor-Programmable Temperature Switch and Analog Temperature Sensor General Description The LM57 is a precision, dual-output, temperature switch with integrated analog temperature sensor. The trip temperature (TTRIP) is programmable by using two external 1% resistors. Using extremely small packaged resistors (0.5 mm x 1 mm), the LM57 can be programmed to any of 256 trip temperatures while consuming very little board space. The VTEMP output delivers an analog output voltage which is proportional with a negative temperature coefficient (NTC) to the measured temperature. Built-in temperature hysteresis (THYST) keeps the output stable in an environment of thermal oscillation. The digital temperature switch outputs will go active when the die temperature exceeds TTRIP and will release when the temperature falls below a temperature equal to TTRIP minus THYST. One of the digital outputs, TOVER, is active-high with a push-pull structure. The other digital output, TOVER, is active-low with an opendrain structure. Driving the TRIP-TEST input high will make the digital outputs active. A processor can read the logic level of the temperature switch outputs, confirming that they changed to their active state. This allows for in-situ verification that the comparator and output circuitry are functional after system assembly. When the TRIP-TEST pin is high, the trip-level reference voltage...