A pulse generator, comprising: a plurality of electrode nodes, each electrode node configured to be coupled to an electrode to provide stimulation pulses to a patient's tissue; and digital-to-analog converter circuitry configurable into first and second modes of operation via one of more control signals, the DAC circuitry comprising a plurality of source circuits each configured to source a current to any of the plurality of electrodes nodes, and a plurality of sink circuits each configured to sink a current from any of the plurality of electrodes nodes, wherein the one or more control signals are received at each of the plurality of source circuits and each of the plurality of sink circuits, wherein the DAC circuity is configurable using the one or more control signals into the first mode of operation in which a plurality of pairs are defined each comprising one of the source circuits and one of the sink circuits, wherein each of the pairs is independently controllable to source and sink currents to selected ones of the electrode nodes in an independent timing channel, and wherein the DAC circuitry is configurable using the one or more control signals into the second mode of operation in which a single pair is defined comprising all of the plurality of source circuits combined and all of the plurality of sink circuits combined, wherein the single pair is controllable to source and sink currents to selected ones of the electrode nodes in a single timing channel. a plurality of electrode nodes, each electrode node configured to be coupled to an electrode to provide stimulation pulses to a patient's tissue; and digital-to-analog converter circuitry configurable into first and second modes of operation via one of more control signals, the DAC circuitry comprising a plurality of source circuits each configured to source a current to any of the plurality of electrodes nodes, and a plurality of sink circuits each configured to sink a current from any of the plurality of electrodes nodes, wherein the one or more control signals are received at each of the plurality of source circuits and each of the plurality of sink circuits, a plurality of source circuits each configured to source a current to any of the plurality of electrodes nodes, and a plurality of sink circuits each configured to sink a current from any of the plurality of electrodes nodes, wherein the one or more control signals are received at each of the plurality of source circuits and each of the plurality of sink circuits, wherein the DAC circuity is configurable using the one or more control signals into the first mode of operation in which a plurality of pairs are defined each comprising one of the source circuits and one of the sink circuits, wherein each of the pairs is independently controllable to source and sink currents to selected ones of the electrode nodes in an independent timing channel, and wherein the DAC circuitry is configurable using the one or more control signals into the second mode of operation in which a single pair is defined comprising all of the plurality of source circuits combined and all of the plurality of sink circuits combined, wherein the single pair is controllable to source and sink currents to selected ones of the electrode nodes in a single timing channel.