Temperature switches, also known as trip point temperature sensors, are simply temperature switches that trip when the temperature exceeds or goes under a specified limit. These devices are used as a temperature alarm when only the fact that the temperature is higher or lower than required is of interest, rather than the actual temperature value. Generally, the user cannot read the actual temperature from these devices. An exception is the TMP01, which also has a voltage output proportional to temperature, as well as temperature alarm functionality. The typical application shown is a temperature window alarm. If the temperature goes outside the upper or lower limits, the out of range signal becomes active.