Micropower Temperature Switch in SOT-23: ADT6401,ADT6503 Trip point +5°C, hysteresis of 2°C:
www.analog.com/en/products/analog-to-digital-converters/integrated-special-purpose-converters/digital-temperature-sensors/adt6401.html
www.analog.com/en/products/analog-to-digital-converters/integrated-special-purpose-converters/digital-temperature-sensors/adt6503.html#product-overview