A lighting circuit (A) includes an input (10), which supplies a single switch ballast (12), which in turn powers a lamp (14). Ballast (12) is in a self-starting, self-oscillating class E converter configuration, which allows for adjustment of the switching duty ratio. Self-oscillation occurs due to the use of regenerative feedback path consisting of a first winding (36), feedback inductor (40), and charging capacitor 42. Increasing output to MOSFET switch (34) occurs once MOSFET switch (34) has been biased to an on state through inputs from input circuit (12), which have been supplied from current source (32). Adjustment of the switching ratio for MOSFET switch (34) is accomplished by selection of appropriate values for zener diodes (48, 50), wherein the voltage breakdown of the zener diode 50 is greater than zener diode 48 reduce the duty ratio to less than 50%, thereby reducing the voltage rating of the switch. Control of the switching ratio allows for switches with lower voltage ratings when driving lamp (14) in this single switching configuration.