A tissue stimulating system includes an external transmitter for transmitting a data signal to an implanted stimulator. The implanted stimulator includes a processor for generating stimulation signals for application to a plurality of tissue stimulating electrodes through respective isolated output channels. The implanted stimulator also includes a power supply that extracts a raw power signal from the data signal. A voltage downconverter generates at least four separate voltages from the extracted raw power signal by alternately connecting at least four capacitors in series across the raw power signal, thereby providing at least four output voltages, and then connecting the capacitors in parallel to transfer the charge stored thereon to a storage capacitor, which serves as the power source for portions of the stimulator. A selected one of the output voltages from the voltage downconverter is applied to an isolated refresh voltage capacitor in each output channel, where it controls a voltage controlled current source. The processor selectively monitors the electrodes and/or voltages generated in the stimulator and generates status indicating/measurement signals for transmission to the external transmitter. The external processor receives and processes the status indicating/measurement signals and uses the information therefrom to control the amount of power transmitted to the stimulator.