Switching power supplies made in accordance with the disclosed technology drive flash lamps of dermatologic treatment devices to emit a sequence of relatively small light pulses that are aligned with particular locations within the waveform of the AC line source. Such power supplies not only enable sufficient light energy in aggregate to therapeutically heat target chromophores in a skin region without causing undesired damage to surrounding tissue, but also provide the added benefit that the corresponding electrical energy need not be substantially drawn from any charged capacitor. The disclosed power supply further compensates for performance degradation of the flash lamps during their usable life, by modifying its operation based on predetermined values that are indicative of flash lamp aging/efficiency characteristics. The flash lamps and their associated stored values are preferably incorporated into a replaceable cartridge that facilitates user maintenance of the dermatologic treatment device.