Patent ID: 7382167

Claim:
A switched hysteresis circuit comprising: an input node coupled to receive a variable voltage input; a first comparator having a first input coupled to the input node to receive a first voltage proportional to the voltage at the voltage input, and a second input coupled to receive a first reference threshold voltage; a second comparator having a first input coupled to the input node to receive a second voltage proportional to the voltage at the voltage input and different from the first voltage, and a second input coupled to receive a second reference threshold voltage different from the first reference threshold voltage; and a logic circuit including a circuit for performing a logical AND function and coupled to outputs of the first and second comparators, the logic circuit having a bilevel state voltage output, the state of the logic circuit output being controlled in response to the outputs of the comparators to provide an adjustable level of hysteresis, the logic circuit output changing from a first logic state to a second logic state when both the first and second voltages are above a highest voltage among the first and second reference threshold voltages, and the logic circuit output changing from the second logic state to the first logic state when both the first and second voltages are below a lowest voltage among the first and second reference threshold voltages.