LM57 Series

The LM57 device is a precision, dual-output, temperature switch with analog temperature sensor output for wide temperature industrial applications. The trip temperature (TTRIP) is selected from 256 possible values in the range of –40°C to +150°C. The VTEMPis a class AB analog voltage output that is proportional to temperature with a programmable negative temperature coefficient (NTC). Two external 1% resistors set the TTRIPand VTEMPslope. The digital and analog outputs enable protection and monitoring of system thermal events. Built-in thermal hysteresis (THYST) prevents the digital outputs from oscillating. The TOVERandTOVERdigital outputs will assert when the die temperature exceeds TTRIPand will de-assert when the temperature falls below a temperature equal to TTRIPminus THYST. TOVERis active-high with a push-pull structure.TOVERis active-low with an open-drain structure. Tying TOVERto TRIP-TEST will latch the output after it trips. The output can be cleared by forcing TRIP-TEST low. Driving the TRIP-TEST high will assert the digital outputs. A processor can check the state of TOVERorTOVER, confirming they changed to an active state. This allows for in-situ verification that the comparator and output circuitry are functional after system assembly. When TRIP-TEST is high, the trip-level reference voltage appears at the VTEMPpin. The system could then use this voltage to calculate the threshold of the LM57. The LM57 device is a precision, dual-output, temperature switch with analog temperature sensor output for wide temperature industrial applications. The trip temperature (TTRIP) is selected from 256 possible values in the range of –40°C to +150°C. The VTEMPis a class AB analog voltage output that is proportional to temperature with a programmable negative temperature coefficient (NTC). Two external 1% resistors set the TTRIPand VTEMPslope. The digital and analog outputs enable protection and monitoring of system thermal events. Built-in thermal hysteresis (THYST) prevents the digital outputs from oscillating. The TOVERandTOVERdigital outputs will assert when the die temperature exceeds TTRIPand will de-assert when the temperature falls below a temperature equal to TTRIPminus THYST. TOVERis active-high with a push-pull structure.TOVERis active-low with an open-drain structure. Tying TOVERto TRIP-TEST will latch the output after it trips. The output can be cleared by forcing TRIP-TEST low. Driving the TRIP-TEST high will assert the digital outputs. A processor can check the state of TOVERorTOVER, confirming they changed to an active state. This allows for in-situ verification that the comparator and output circuitry are functional after system assembly. When TRIP-TEST is high, the trip-level reference voltage appears at the VTEMPpin. The system could then use this voltage to calculate the threshold of the LM57.