Patent ID: 7808304

Claim:
A current switch to disable a driver circuit during a startup period, the current switch comprising: a bias generation circuit electrically connected to a high voltage power supply to generate a biasing current during the startup period of the driver circuit in which an internal power supply fails to supply an internal voltage; a current mirror electrically connected to said bias generation circuit and a ground, comprising a first plurality of transistors electrically connected to each other to receive the bias current and output a mirrored bias current; a second plurality of transistors electrically connected to said current mirror and each other to receive the mirrored bias current, wherein a first one of said second plurality of transistors receives and amplifies the mirrored bias current according to a predetermined amplification ratio, and a second and a third one of said second plurality of transistors receive the amplified mirrored bias current, wherein a source of the second one of said second plurality of transistors is electrically connected to the high voltage power supply and a drain of the second one of said second plurality of transistors is electrically connected to a node shared by an internal reference voltage to sink the amplified mirrored bias current into the internal reference voltage node to put the internal reference voltage node in a first logic state, wherein a source of the third one of said second plurality of transistors is electrically connected to the high voltage power supply and a drain of the third one of said second plurality of transistors is electrically connected to a node shared by a gate of a high voltage transistor to sink the amplified mirrored bias current into the high voltage transistor gate node to put the high voltage transistor gate node in the first logic state, and wherein putting the nodes in the first logic state turns off the high voltage transistor.