Patent ID: 8014866

Claim:
An apparatus for delivering electrical neural stimulation therapy to a patient comprising an implantable medical device and an external device, the implantable medical device comprising: a power supply terminal adapted to be connected to a power supply, circuitry connected to the power supply terminal and adapted to detect tissue/electrode interface impedances; and a current output pulse generator comprising a programmed amplitude of stimulation current, wherein the generator is adapted to deliver electrical neural stimulation therapy at the programmed amplitude, the generator further comprising: an adjustable compliance voltage source connected to the power supply terminal, the voltage source comprising an adjustable voltage level and is adapted to provide different potentials for different tissue/electrode interface impedances; and a controller adapted to receive the detected impedances, maintain the programmed amplitude of stimulation current for the different tissue/electrode interface impedances and adjust the compliance voltage source by adjusting the voltage level based on the programmed amplitude of the stimulation current and the detected impedances.