Patent ID: 7724069

Claim:
A switch circuit which selectively couples first and second switch nodes together and which enables the first and second switch nodes to operate in an extended voltage range outside a normal voltage range which is between first and second supply voltage rails, comprising: a secondary voltage rail; a switch device having a current path coupled between the first and second switch nodes, a control terminal, and a body, wherein said switch device couples the first and second switch nodes together when turned on; a body driver coupled between said body of said switch device and said secondary voltage rail, wherein said body driver device clamps said body of said switch device to said secondary voltage rail when turned on, and forward biases to allow voltage of said secondary voltage rail to follow voltage of said body of said switch device if voltage of said body of said switch device extends outside voltage of the second supply rail into the extended voltage range when turned off; a rail control switch having a current path coupled between the second supply voltage rail and said secondary voltage rail, having a first control terminal coupled to the first switch node and a second control terminal coupled to the second switch node, wherein said rail control switch clamps said secondary voltage rail to said second supply voltage rail when the first and second switch nodes are both within the normal voltage range, and wherein said rail control switch releases said secondary voltage rail if voltage of either one of the first and second switch nodes extends into said first extended voltage range; and a switch control circuit which switches between an on state and an off state, wherein in said on state, said switch control circuit clamps said control terminal of said switch device to the first supply voltage rail and turns off said body driver, and wherein in said off state, said switch control circuit clamps said control terminal of said switch device to said secondary voltage rail and turns on said body driver.