Patent ID: 8731682

Claim:
A stimulation system, comprising: (i) an implantable pulse generator (IPG) that comprises: a first rechargeable battery for powering the IPG; pulse generating circuitry; a first coil for receiving RF power; a rectifier coupled to the first coil; and first control circuitry for controlling RF power conversion, wherein the first control circuitry clamps a first circuit node and a second circuit node, each connected to the first coil, to ground to limit further conversion of RF power by the rectifier when a power conversion voltage exceeds a predefined level; and (ii) an external charging device for recharging the IPG, comprising: a second rechargeable battery for powering the external charging device; a second coil for radiating RF power; drive circuitry for driving the second coil according to a duty cycle; circuitry for generating a signal that is indicative of an amount of current flowing through the second coil; and second control circuitry for controlling the drive circuitry, wherein the external charging device is operable to process the signal from the circuitry for generating to detect clamping of the first and second circuit nodes connected to the first coil to ground, the external charging device modifying the duty cycle in response to detection of the clamping of the first and second circuit nodes in the IPG to ground.