Temperature threshold circuit with hysteresis

摘要

A circuit for determining a threshold indication of temperature with respect to a threshold temperature. The circuit includes a timer circuit and a temperature sensor circuit having an counter whose output has a relationship to temperature. At the end of a period determined by the timer circuit, a comparator circuit compares the count of the counter with an indication of the threshold temperature to determine a state of the threshold indication. In response to a change in state of the threshold indication, the circuit changes one of the count time or the counter output's relationship to temperature to provide a hysteresis for the threshold indication.

主权项

1. A temperature threshold circuit comprising:
a temperature sensor including a first oscillator and first counter, a count rate of the first counter is controlled by the first oscillator, the temperature sensor including an output for providing a count indicative of a temperature; a timer circuit including an output; a storage device for storing an indication of a threshold temperature; a threshold indication circuit including a comparator for comparing the output of the first counter with the indication of the threshold temperature at a time indicated by the output of the timer circuit to provide a threshold indication of temperature with respect to the threshold temperature based on the comparing, wherein one of a count time of the timer circuit or a count to temperature relationship of the output of the temperature sensor is changed based on a change of state of the threshold indication.