Thermostat ±1.5°C Push-Pull/Open Drain SMD 8-Pin WSON T/R

The LM57 is a precision, dual-output, temperature switch withintegrated 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 temperatureswhile consuming very little board space. The VTEMP outputdelivers an analog output voltage which is proportional with anegative temperature coefficient (NTC) to the measured temperature.Built-in temperature hysteresis (THYST) keeps the output stablein an environment of thermal oscillation. The digital temperatureswitch outputs will go active when the die temperatureexceeds TTRIP and will release when the temperature fallsbelow a temperature equal to TTRIP minus THYST. One of thedigital outputs, TOVER, is active-high with a push-pull structure.The other digital output, TOVER, is active-low with an opendrainstructure.Driving the TRIP-TEST input high will make the digital outputsactive. A processor can read the logic level of the temperatureswitch outputs, confirming that they changed to their activestate. This allows for in-situ verification that the comparatorand output circuitry are functional after system assembly.When the TRIP-TEST pin is high, the trip-level reference voltageappears at the Vtemp pin. The system could then use thisvoltage to calibrate the sensor for even tighter accuracy. TyingTOVER to TRIP-TEST will latch the output after it trips. Itcan be cleared by forcing TRIP-TEST low or powering off theLM57.As it draws only 28µA max from its supply, it has very low selfheating,about 0.02°C in still air.

• Trip temperature set by external resistors
• External resistor tolerance contributes zero error
• Push-pull and open-drain temperature switch outputs
• Wide operating temperature and trip-temperature range of -50°C to 150°C
• Very linear analog VTEMP temperature sensor output
• Analog and digital outputs are short-circuit protected
• TRIP-TEST pin allows in-system testing
• Latching function for the digital outputs
• Very small 2.5 mm by 2.5 mm 8-Pin LLP package