LM57

Probe domestic switch needle KG-300K needle head diameter is 3.0mm normally open switch needle

Photocoupler

[Applications] Temperature sensor

The LM57 is a high precision, dual output, integrated, analog temperature sensor temperature switch. By using two external 1% resistors, the trip temperature (TTRIP) is programmable and can be any 256 trip temperature and takes up very little board space.

TI's LM57 is a high precision, dual output, integrated, analog temperature sensor temperature switch. The trip temperature (TTRIP) is programmable by using two external 1% resistors. The LM57 uses a very small package of resistors (0.5mm x 1mm) that can be programmed to any 256 trip temperature and takes up very little board space. The VTEMP output can provide an analog output voltage with a negative temperature coefficient (NTC) that is proportional to the measured temperature.

The built-in temperature hysteresis (THYST) of the LM57 device keeps the output stable (in a thermally oscillating environment). When the die temperature exceeds TTRIP, the digital temperature switch output will be activated and when the temperature is below TTRIP minus THYST, the digital temperature switch output will be released. One of the digital outputs, TOVER, is a highly active push-pull structure. For other digital outputs, TOVER is a low active open-drain configuration.

Figure 1 LM57 internal block diagram

If the TRIP-TEST input is high, the digital output will be active. A processor can read the logic levels of the temperature switch outputs to confirm that they are active. This allows for on-site verification, and the comparator and output circuits function properly after system assembly. When the TRIP-TEST pin is high, the trip level reference voltage appears on the VTEMP pin. The system can then use this voltage to more closely calibrate the accuracy of the sensor. Connecting TOVER to TRIP-TEST latches the output after the output is disconnected. It can be removed by forcibly depressing TRIP-TEST or by setting the LM57 to power down.

Table 1 List of LM57 program materials

Since the maximum current consumes only 28μA, the device has very low self-heating, about 0.02 ° C in still air.

[Substitution interchange compatible]

[LM57 original (Chinese) data sheet (Datasheet) package PDF]