Implantable device with output circuitry for simultaneous stimulation at multiple sites

DETAILED DESCRIPTION In view of the above object, there is provided an implantable battery-powered device having two or more output stages which enable stimulation at two or more stimulation sites concurrently, the two or more output stages being supplied from a single battery and without crosscurrents from one stage to another.
The stimulator output stages use energy storage devices such as capacitors as temporary floating power sources during stimulation.
Two or more such sources with the appropriate stored pacing energy are connected to respective loads for concurrent stimulation.
At the time of delivery of the pulses, the load voltages are monitored, and for the IC type described as the preferred embodiment of this invention the load output which is most negative is connected to the positive terminal of the battery, while the other output circuit is disconnected from the battery so that it is floating.
Depending on the IC type or process which is utilized, i.
e.
, N or P doped channels, it may be required to reference the load to the battery terminals differently.
This connection at time of stimulation achieves the dual aims of eliminating a closed path through a common battery reference, thereby minimizing crosstalk currents; and maintains only positive voltages on the circuit switching elements with respect to system ground, such that no such elements (FETs) are driven to a state of parasitic conduction.