Spinal cord stimulation occurring using monophasic pulses of alternating polarities and passive charge recovery

New waveforms for use in an implantable pulse generator or external trial stimulator are disclosed which mimic actively-driven biphasic pulses, and which are particularly useful for issuing low frequencies pulses. The waveforms comprise at each electrode interleaved first and second pulses. Each first pulse comprises a first monophasic pulse and a first passive charge recovery period. Each second pulse comprises a second monophasic pulse with a polarity opposite the first monophasic pulse and a second passive charge recovery period. Preferably, the amplitudes and pulse widths of the first and second monophasic pulses are equal, or at least charge balanced at each electrode. The first and second monophasic pulses mimic the functionality of a symmetric biphasic pulse, with the first monophasic pulse mimicking the functionality of the biphasic pulse's first phase, and the with the second monophasic pulse mimicking the functionality of the biphasic pulse's second phase.