Backlighting in portable device displays has historically used cold cathode-fluorescent (CCFL) tubes which are difficult to power. The tubes run on alternating current (AC) and need a large initial voltage of typically greater than 1 kV to start. Once they have fired, their operating voltage drops to under a kV. Because a notebook computer, for example, typically operates on low DC values (12V, 5V, 3.3V, etc.), a Royer oscillator must be used to transform this low voltage to the high-voltage AC required by the CCFL, a potential safety hazard.