Patent attributes
A thermostat circuit is arranged for dual purpose operation to save pins in a small package. The circuit includes a temperature sensor circuit, a trip-point reference circuit, a switching circuit, an amplifier circuit, and a comparator circuit. The trip-point reference circuit provides a reference voltage that corresponds to a desired trip-point level. The temperature sensor circuit provides a sense voltage that corresponds to temperature. During a normal operating mode the sense voltage is coupled to the input of the amplifier circuit via the switching circuit, while during a test mode the reference voltage is coupled to an input of the amplifier circuit. The amplifier circuit buffers a voltage to one output pin. The comparator circuit compares the reference voltage to the sense voltage to provide a trip-point detection voltage for another output pin. An input pin is provided for selection of either a test mode or a non-test mode.
