Patent ID: 7212020

Claim:
An isolation device for isolating a circuit and an external terminal comprising: control circuitry for sensing current to ground in an 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 outputting the control signal in response thereto, circuitry for sensing a voltage applied to the internal circuit below the predetermined threshold and outputting the control signal in response thereto, or circuitry for sensing a voltage applied to the internal circuit above the predetermined threshold and 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.