1. Field of the Invention
The present invention relates to a voltage boosting circuit for keeping the power factor controller of an electric device enabled when the ac or dc voltage supplying the electric device is lower than a predetermined voltage threshold.
2. Brief Description of the Prior Art
As well known to those of ordinary skill in the art, stand alone systems require loads with low power requirements. For that reason, there presently exists a high demand for light-emitting-diode (LED) lamps for use in traffic lights in hard-to-reach distant regions.
To be used in traffic lights in hard-to-reach distant regions, LED lamps must meet with stringent requirements. For example, in railway signalling, stringent requirements related to power requirement, robustness and power supply flexibility have to be met.
In particular, railway signalling LED lamps must operate at low supply voltage level and accept both alternating and direct currents. Moreover, the power factor must be situated as close as possible to 1 to prevent oversizing of the back-up systems.