Image Number 2 for United States Patent #6856100.
A ballast (20, 20') includes a rectifier circuit (100), a boost converter (200, 200'), an inverter (300), an output circuit (400), and an inverter startup circuit (600). Inverter startup circuit (600) is coupled between boost converter (200) and inverter (300). During operation, inverter startup circuit (600) provides a delay period between startup of boost converter (200) and startup of inverter (300) so that startup of inverter (300) is delayed until at least such time as the DC rail voltage provided by boost converter (200) approaches its steady-state operating level. This ensures that the ballast (20,20') provides an output voltage that is sufficiently high to ignite a lamp (40) in a preferred manner, with little or no glow current and a fast strike time.