A
spinal cord stimulation (SCS)
system includes multiple electrodes, multiple, independently programmable, stimulation channels within an implantable
pulse generator (IPG) which channels can provide concurrent, but unique stimulation fields, permitting virtual electrodes to be realized. The SCS
system includes a replenishable power source (e.g., rechargeable battery), that may be recharged using transcutaneous power transmissions between antenna coil pairs. An external charger unit, having its own rechargeable battery can be used to charge the IPG replenishable power source. A real-time
clock can provide an auto-run schedule for daily stimulation. An included bi-directional
telemetry link in the
system informs the patient or clinician the status of the system, including the
state of charge of the IPG battery. Other
processing circuitry in the IPG allows
electrode impedance measurements to be made. Further circuitry in the external
battery charger can provide alignment detection for the coil pairs.