Battery powered fluorescent lighting is an important application area that significantly benefits from the low saturation voltage exhibited by Zetex Super-β transistors. These transistors replace the TO126 and TO220 types commonly used in this application, giving savings in cost and size whilst providing improvements in efficiency too. Since most of the circuit losses now occur in the magnetic components and base drive, this translates to excellent circuit efficiency and extended battery life. Furthermore, the low power losses in transistors minimise temperature rises in them – important in reliability terms.
Emergency lighting systems are frequently employed as a required safety feature within business premises. These systems essentially comprise a control circuit, a battery pack, a trickle charging circuit, and either an in-built incandescent lamp, or an inverter that will allow the battery supply to drive the existing fluorescent tubes. It is the latter version, and the requisite DC-AC inverter that are addressed within this application note.