Patent ID: 7034561

Claim:
An integrated circuit having an internal circuit and an external terminal for communicating between the internal circuit and external circuitry to the integrated circuit, the external terminal for receiving a supply voltage from the circuitry external to the integrated circuit, comprising: a device for isolating the internal circuit from the external terminal, the device comprising: control circuitry for sensing current to ground at a predetermined level in the internal circuit and outputting a control signal in response thereto, the control circuitry including one of circuitry for sensing current drawn by the internal circuit exceeding a predetermined threshold and for outputting the control signal in response thereto, circuitry for sensing a voltage applied to the internal circuit below the predetermined threshold and for outputting the control signal in response thereto, and circuitry for sensing a voltage applied to the internal circuit above the predetermined threshold and for outputting the control signal in response thereto, the control circuitry comprising: a first transistor having a source coupled to a supply terminal, a gate coupled to an output terminal, and a drain coupled to a control signal terminal; a first resistive device coupled between the supply terminal and the output terminal; a second resistive device coupled between the control signal terminal and a reference voltage bond pad; a second transistor having a source coupled to the supply terminal, a gate, and a drain coupled to the control signal terminal; an inverter coupled between the control signal terminal and the gate of the second transistor; and circuitry for sensing the voltage applied to the internal circuit; and switching circuitry coupled to the control circuitry for isolating the internal circuit from the external terminal in response to receiving the control signal.