Abstract: A dual sourced voltage supply circuit for use with a flash EPROM or the like and comprising output voltage circuitry including an input for receiving a control signal determining which of two voltage supplies is used to provide an output of the dual sourced voltage supply circuit. The output voltage is provided by one of the two voltage supplies by means of a controllable conductive path connected between one voltage supply and an output node of the circuit.

Abstract: A threshold detection circuit for generating a detection signal when a power supply voltage exceeds a predetermined threshold. The threshold detection circuit comprises a first detection stage, a second detection stage, and a control circuitry. The first detection stage is connected between the power supply voltage and a reference voltage, and includes a first pull-up device and a first switching device connected in series and provides a control node therebetween. The second detection stage is connected between the power supply voltage and the reference voltage and includes a controllable pull down device and a second switching device connected in series, and provides an output node therebetween. The controllable pull down device has a control terminal coupled to the control node. Finally, the control circuitry controls the first and second switching devices to prevent a DC path between the power supply voltage and the reference voltage outside an operational voltage range of the threshold detection circuit.