Patent ID: 7609734

Claim:
A current driver circuit for driving a load (LD), comprising: first and second transistors (Q 1 ) and (Q 2 ) that function as a current mirror when gates of the first and second transistors (Q 1 ) and (Q 2 ) are selectively connected together, with a drain of the first transistor (Q 1 ) forming an input of the current mirror, a drain of the second transistor (Q 2 ) forming an output of the current mirror, and the drain of the second transistor (Q 2 ) also forming the output of the current driver circuit; a current source (Icontrol) the provides a control current; a load mimic circuit ( 1308 ) through which the control current flows, and that provides a voltage approximately equal the voltage at the output of the current driver circuit, when an output current (Iout) provided at the output of the current driver circuit is driving the load (LD); a control loop that uses the load mimic circuit ( 1308 ) to cause the voltage at the drain of the first transistor (Q 1 ) to approximately equal the voltage at the output of the current driver circuit, when the output current (Iout) provided at the output of the current driver circuit is driving the load (LD); and a controller that controls whether or not the gates of the first and second transistors (Q 1 ) and (Q 2 ) are connected together, and that causes the second transistor (Q 2 ) to be turned off when the gates of the first and second transistors (Q 1 ) and (Q 2 ) are not connected together.